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Journal articles on the topic 'Bacterial growth curve'
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Paulton, Richard J. L. "The bacterial growth curve." Journal of Biological Education 25, no. 2 (June 1991): 92–94. http://dx.doi.org/10.1080/00219266.1991.9655183.
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Irdawati, Irdawati, Ilsa Septia Putri, Syamsuardi Syamsuardi, Anthoni Agustien, and Yetria Rilda. "The Thermophilic Bacterial Growth Curve." Bioscience 2, no. 2 (October 30, 2018): 58. http://dx.doi.org/10.24036/0201822100819-0-00.
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Zwietering, M. H., I. Jongenburger, F. M. Rombouts, and K. van 't Riet. "Modeling of the Bacterial Growth Curve." Applied and Environmental Microbiology 56, no. 6 (1990): 1875–81. http://dx.doi.org/10.1128/aem.56.6.1875-1881.1990.
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Krishnamurthi, Venkata Rao, Isabelle I. Niyonshuti, Jingyi Chen, and Yong Wang. "A new analysis method for evaluating bacterial growth with microplate readers." PLOS ONE 16, no. 1 (January 12, 2021): e0245205. http://dx.doi.org/10.1371/journal.pone.0245205.
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Growth curve measurements are commonly used in microbiology, while the use of microplate readers for such measurements provides better temporal resolution and higher throughput. However, evaluating bacterial growth with microplate readers has been hurdled by barriers such as multiple scattering. Here, we report our development of a method based on the time derivatives of the optical density (OD) and/or fluorescence (FL) of bacterial cultures to overcome these barriers. First, we illustrated our method using quantitative models and numerical simulations, which predicted the number of bacteria and the number of fluorescent proteins in time as well as their time derivatives. Then, we systematically investigated how the time derivatives depend on the parameters in the models/simulations, providing a framework for understanding the FL growth curves. In addition, as a demonstration, we applied our method to study the lag time elongation of bacteria subjected to treatment with silver (Ag+) ions and found that the results from our method corroborated well with that from growth curve fitting by the Gompertz model that has been commonly used in the literature. Furthermore, this method was applied to the growth of bacteria in the presence of silver nanoparticles (AgNPs) at various concentrations, where the OD curve measurements failed. We showed that our method allowed us to successfully extract the growth behavior of the bacteria from the FL measurements and understand how the growth was affected by the AgNPs.
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Boonkitticharoen, Vipa, James C. Ehrhardt, and Peter T. Kirchner. "Bacterial growth kinetics: modelling and evaluation of two-compartment radioassay." Canadian Journal of Microbiology 35, no. 9 (September 1, 1989): 874–80. http://dx.doi.org/10.1139/m89-146.
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Quantitative measurements of bacterial growth may be made using a radioassay technique. This method measures, by scintillation counting, the 14CO2 derived from die bacterial metabolism of a 14C-labeled substrate. Mathematical growth models may serve as reliable tools for estimation of the generation rate constant (or slope of the growth curve) and provide a basis for evaluating assay performance. Two models, i.e., exponential and logistic, are proposed. Both models yielded an accurate fit to the data from radioactive measurement of bacterial growth. The exponential model yielded high precision values of the generation rate constant, with an average relative standard deviation of 1.2%. Under most conditions the assay demonstrated no changes in the slopes of growth curves when the number of bacteria per inoculation was changed. However, the radiometric assay by scintillation method had a growth-inhibiting effect on a few strains of bacteria. The source of this problem was thought to be hypersensitivity to trace amounts of toluene remaining on the detector.Key words: bacterial growth modelling.
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Stiller, Alison, Ashley Fink, and David Mitchell. "Bacillus cereus & Bacillus pumilus Harvested from a Copper Roof Inhibit the Growth of Other Microorganisms." American Journal of Undergraduate Research 17, no. 2 (September 30, 2020): 3–11. http://dx.doi.org/10.33697/ajur.2020.016.
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Bacteria growing under the effects of unique selective pressures have distinct adaptations allowing them to survive. Copper surfaces present challenges for bacterial survival because ions dissolve from the surfaces and disrupt cell membranes, thus inhibiting bacterial growth. In this study, the copper roof of Simons Hall in Collegeville, Minnesota was sampled for bacterial species during November 2018. Bacteria were isolated and grown in culture, and zones of inhibition were identified surrounding three of the bacterial colonies. Polymerase chain reaction (PCR) was used to identify two of the bacteria samples as Bacillus cereus and a third sample as Bacillus pumilus. Bacilli are large, rod-shaped, gram-positive bacteria commonly found in diverse environments. They are endospore-forming aerobes or facultative anaerobes. Initial experiments indicated that all three Bacillus strains had the ability to inhibit the growth of three environmental microorganisms. Results from growth curve experiments depicted inhibitory effects on environmental microorganisms at all stages of the growth curve, which is contrary to the prediction that the inhibitory behavior would appear at one specific period of the growth curve. Additional experiments involved plating isolates of Bacillus cereus and Bacillus pumilus with laboratory samples of Pseudomonas aeruginosa, Streptococcus pneumoniae, and Listeria monocytogenes to further understand the effectiveness of B. cereus and B. pumilus at inhibiting the growth of other microorganisms. These findings support previous studies and suggest that Bacillus are capable of inhibiting or killing other organisms. Further research will be conducted to illuminate the inhibitory mechanisms and identify potential therapeutic possibilities. KEYWORDS: Bacteria; Copper; Resistance; Growth Curve; Inhibition; Bacillus; Bacteriocin; Antimicrobial Peptides
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Woeste, Steven, and Paul Demchick. "A slow bacterial growth curve exercise for laboratory classrooms." Journal of Biological Education 30, no. 2 (June 1996): 91–92. http://dx.doi.org/10.1080/00219266.1996.9655484.
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Cao, Yang-Yang, Tetsuya Yomo, and Bei-Wen Ying. "Clustering of Bacterial Growth Dynamics in Response to Growth Media by Dynamic Time Warping." Microorganisms 8, no. 3 (February 26, 2020): 331. http://dx.doi.org/10.3390/microorganisms8030331.
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Bacterial growth curves, representing population dynamics, are still poorly understood. The growth curves are commonly analyzed by model-based theoretical fitting, which is limited to typical S-shape fittings and does not elucidate the dynamics in their entirety. Thus, whether a certain growth condition results in any particular pattern of growth curve remains unclear. To address this question, up-to-date data mining techniques were applied to bacterial growth analysis for the first time. Dynamic time warping (DTW) and derivative DTW (DDTW) were used to compare the similarity among 1015 growth curves of 28 Escherichia coli strains growing in three different media. In the similarity evaluation, agglomerative hierarchical clustering, assessed with four statistic benchmarks, successfully categorized the growth curves into three clusters, roughly corresponding to the three media. Furthermore, a simple benchmark was newly proposed, providing a highly improved accuracy (~99%) in clustering the growth curves corresponding to the growth media. The biologically reasonable categorization of growth curves suggested that DTW and DDTW are applicable for bacterial growth analysis. The bottom-up clustering results indicate that the growth media determine some specific patterns of population dynamics, regardless of genomic variation, and thus have a higher priority of shaping the growth curves than the genomes do.
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Cuevas, Daniel A., and Robert A. Edwards. "PMAnalyzer: a new web interface for bacterial growth curve analysis." Bioinformatics 33, no. 12 (February 13, 2017): 1905–6. http://dx.doi.org/10.1093/bioinformatics/btx084.
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Wajima, Takeaki, Reina Kinugawa, Tetsuya Yamada, Hideaki Ikoshi, and Norihisa Noguchi. "Panax Notoginseng Extract Possesses Significant Antibacterial Activity against Pathogenic Streptococci." Pharmacology 103, no. 5-6 (2019): 221–27. http://dx.doi.org/10.1159/000496830.
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Background: In traditional Chinese medicine, Panax notoginseng is used to treat inflammation and bleeding but has not been shown to affect bacterial pathogens. Objectives: Our aim was to assess the antibacterial potential of Panax notoginseng extract (PNE) against bacterial pathogens. Methods: PNE was dissolved in autoclaved distilled water. Antimicrobial activity was measured by the disc diffusion test and bacterial growth curve assays, in which the concentration of bacterial colony forming units was monitored at several time points in the presence or absence of PNE. Results: Disc diffusion and growth curve assays demonstrated that PNE significantly inhibited the growth of Streptococcus pyogenes, Streptococcus pneumoniae, and Haemophilus influenzae (p < 0.05). In contrast, the growth of the oral commensal bacteria Streptococcus intermedius, Streptococcus salivarius, and Streptococcus anginosus was not inhibited. Therefore, S. pyogenes clinical isolates were analyzed. PNE had antimicrobial effects on all tested isolates in both aerobic and anaerobic conditions. In addition, when S. pyogenes was co-cultured with S. intermedius in the presence of PNE, PNE inhibited the growth of S. pyogenes, but did not inhibit the growth of S. intermedius. Conclusion: Our findings suggested that PNE inhibited S. pyogenes without affecting oral commensal bacteria. Therefore, PNE could be used for the treatment of S. pyogenes infections.
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Miyahara, M., T. Matsumoto, H. Sakurai, and P. Pipek. "The conformability of two equations for bacterial growth in pork." Czech Journal of Food Sciences 20, No. 2 (November 18, 2011): 69–73. http://dx.doi.org/10.17221/3512-cjfs.
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Pork is now distributed as cut meat, which increases the chance of contamination with bacteria. The rate of bacterial growth can be expressed by an exponential function. In order to find how the number of contaminating bacteria increases, we compared two functional equations for a growth curve. They are logistic: Yt = K (1 + m e–at) (1) and Gompertz: log Yt = log K + (log a)bt (2) equations (where Yt = the number of bacteria at the time t in min, m and a = coefficient, e = natural logarithm, K maximum number of bacteria). 90 ml of physiological salt solution was added to 10 g of pork. It was homogenized for 3 min, then incubated at 35°C for 13 hrs. The number of bacteria was counted every hour. We found from these data that the above two equations can be expressed as follows: Yt = 23 535 (1 + 16269 e–1.1608t) and log Yt = 8.9940 + (–3.1124) × 0.7839t. The theoretical and actual values matched well in equation (1), and the number of bacteria can be predicted accurately using this equation at a given time after incubation. The theoretical and actual values did not match well in equation (2) and its accuracy to predict the number of bacteria was very low except the initial number of bacteria was high.
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López, D., M. Viñas, J. G. Lorén, and J. Bermúdez. "Analysis of microcalorimetric curves for bacterial identification." Canadian Journal of Microbiology 33, no. 1 (January 1, 1987): 6–11. http://dx.doi.org/10.1139/m87-002.
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A numeric method is suggested for the treatment of microcalorimetric curves of bacterial growth to provide a new tool for their automatic identification. In this method the microcalorimetric curves are searched against certain reference profiles (stored in a library) by means of a cross-correlation analysis and a parametric comparison. The matching between the new curve and each reference profile is evaluated by means of a specific identification coefficient which provides an objective criterion for the identification of each species. The reliability of the method is discussed.
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Fujikawa, Hiroshi, and Satoshi Morozumi. "Modeling Surface Growth of Escherichia coli on Agar Plates." Applied and Environmental Microbiology 71, no. 12 (December 2005): 7920–26. http://dx.doi.org/10.1128/aem.71.12.7920-7926.2005.
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ABSTRACT Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34°C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves.
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Konopacki, Maciej, Adrian Augustyniak, Bartłomiej Grygorcewicz, Barbara Dołęgowska, Marian Kordas, and Rafał Rakoczy. "Single Mathematical Parameter for Evaluation of the Microorganisms’ Growth as the Objective Function in the Optimization by the DOE Techniques." Microorganisms 8, no. 11 (October 31, 2020): 1706. http://dx.doi.org/10.3390/microorganisms8111706.
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The cultivation of bacteria sets a ground for studying biological processes in many scientific disciplines. The development of the bacterial population is commonly described with three factors that can be used to evaluate culture conditions. However, selecting only one of them for the optimization protocol is rather problematic and may lead to unintended errors. Therefore, we proposed a novel mathematical approach to obtain a single factor that could be used as the objective function to evaluate the whole growth dynamic and support the optimization of the biomass production process. The sigmoidal-shape curve, which is the commonly used function to plot the amount of biomass versus time, was the base for the mathematical analysis. The key process parameters, such as maximal specific growth rate and lag-phase duration were established with the use of mathematical coefficients of the model curve and combined to create the single growth parameter. Moreover, this parameter was used for the exemplary optimization of the cultivation conditions of Klebsiella pneumoniae that was cultured to be further used in the production of lytic bacteriophages. The proposed growth parameter was successfully validated and used to calculate the optimal process temperature of the selected bacterial strain. The obtained results indicated that the proposed mathematical approach could be effortlessly adapted for a precise evaluation of growth curves.
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Kacena, M. A., G. A. Merrell, B. Manfredi, E. E. Smith, D. M. Klaus, and P. Todd. "Bacterial growth in space flight: logistic growth curve parameters for Escherichia coli and Bacillus subtilis." Applied Microbiology and Biotechnology 51, no. 2 (February 25, 1999): 229–34. http://dx.doi.org/10.1007/s002530051386.
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Firsov, A. A., S. N. Vostrov, A. A. Shevchenko, and G. Cornaglia. "Parameters of bacterial killing and regrowth kinetics and antimicrobial effect examined in terms of area under the concentration-time curve relationships: action of ciprofloxacin against Escherichia coli in an in vitro dynamic model." Antimicrobial Agents and Chemotherapy 41, no. 6 (June 1997): 1281–87. http://dx.doi.org/10.1128/aac.41.6.1281.
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Although many parameters have been described to quantitate the killing and regrowth of bacteria, substantial shortcomings are inherent in most of them, such as low sensitivity to pharmacokinetic determinants of the antimicrobial effect, an inability to predict a total effect, insufficient robustness, and uncertain interrelations between the parameters that prevent an ultimate determination of the effect. To examine different parameters, the kinetics of killing and regrowth of Escherichia coli (MIC, 0.013 microg/ml) were studied in vitro by simulating a series of ciprofloxacin monoexponential pharmacokinetic profiles. Initial ciprofloxacin concentrations varied from 0.02 to 19.2 microg/ml, whereas the half-life of 4 h was the same in all experiments. The following parameters were calculated and estimated: the time to reduce the initial inoculum (N0) 10-, 100-, and 1,000-fold (T90%, T99%, and T99.9%, respectively), the rate constant of bacterial elimination (k(elb)), the nadir level (Nmin) in the viable count (N)-versus-time (t) curve, the time to reach Nmin (t(min)), the numbers of bacteria that survived (Ntau) by the end of the observation period (tau), the area under the bacterial killing and regrowth curve (log N(A)-t curve) from the zero point (time zero) to tau (AUBC), the area above this curve (AAC), the area between the control growth curve (log N(C)-t curve) and the bacterial killing and regrowth curve (log N(A)-t curve) from the zero point to tau (ABBC) or to the time point when log N(A) reaches the maximal values observed in the log N(C)-t curve (I(E); intensity of the effect), and the time shift between the control growth and regrowth curves (T(E); duration of the effect). Being highly sensitive to the AUC, I(E), and T(E) showed the most regular AUC relationships: the effect expressed by I(E) or T(E) increased systematically when the AUC or initial concentration of ciprofloxacin rose. Other parameters, especially T90%, T99%, T99.9%, t(min), and log N0 - log Nmin = delta log Nmin, related to the AUC less regularly and were poorly sensitive to the AUC. T(E) proved to be the best predictor and t(min) proved to be the worst predictor of the total antimicrobial effect reflected by I(E). Distinct feedback relationships between the effect determination and the experimental design were demonstrated. It was shown that unjustified shortening of the observation period, i.e., cutting off the log N(A)-t curves, may lead to the degeneration of the AUC-response relationships, as expressed by log N0 - log Ntau = delta log Ntau, AUBC, AAC, or ABBC, to a point where it gives rise to the false idea of an AUC- or concentration-independent effect. Thus, use of I(E) and T(E) provides the most unbiased, robust, and comprehensive means of determining the antimicrobial effect.
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McKernan, Lisa N. "Using a Simple Escherichia coli Growth Curve Model to Teach the Scientific Method." American Biology Teacher 77, no. 5 (May 1, 2015): 357–62. http://dx.doi.org/10.1525/abt.2015.77.5.6.
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The challenge of teaching in the sciences is not only conveying knowledge in the discipline, but also developing essential critical thinking, data analysis, and scientific writing skills. I outline an exercise that can be done easily as part of a microbiology laboratory course. It teaches the nature of the research process, from asking questions and developing a testable hypothesis to writing a scientific paper, as well as the concepts of bacterial growth and two classic techniques for measuring bacterial growth, spectrophotometry, and standard plate method.
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Lavrentyeva, K. V., N. V. Cherevach, and A. I. Vinnikov. "Закономірності росту фосфатмобілізувальних бактерій у різних типах живильних середовищ." Visnyk of Dnipropetrovsk University. Biology, medicine 1, no. 1 (June 12, 2010): 78–82. http://dx.doi.org/10.15421/021013.
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Regularities of two strains of soil phosphate-mobilizing bacteria growth were investigated in different media. Curve of growth and physiological parameters were defined for Pseudomonas putida and Enterobacter dissolvens. Growth pattern of investigated strains was better in the broth medium than in mineral. In these conditions higher concentration of viable bacterial cells was common for E. dissolvens. It was shown that during cultivation pH of mineral medium went down to 4.4-4.5, but broth medium had constant pH 7.0.
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Krepsky, N., FS Da Silva, LF Fontana, and MAC Crapez. "Alternative methodology for isolation of biosurfactant-producing bacteria." Brazilian Journal of Biology 67, no. 1 (February 2007): 117–24. http://dx.doi.org/10.1590/s1519-69842007000100016.
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Wide biosurfactant application on biorremediation is limited by its high production cost. The search for cheaper biossurfactant production alternatives has guided our study. The use of selective media containing sucrose (10 g.L-1) and Arabian Light oil (2 g.L-1) as carbon sources showed to be effective to screen and maintain biosurfactant-producing consortia isolated from mangrove hydrocarbon-contaminated sediment. The biosurfactant production was assayed by kerosene, gasoline and Arabian Light Emulsification activity and the bacterial growth curve was determined by bacterial quantification. The parameters analyzed for biosurfactant production were the growth curve, salinity concentration, flask shape and oxygenation. All bacteria consortia screened were able to emulsify the petroleum derivatives tested. Biosurfactant production increased according to the incubation time; however the type of emulsification (non-aqueous phase or aqueous phase) did not change with time but with the compound tested. The methodology was able to isolate biosurfactant-producing consortia from superficial mangrove sediment contaminated by petroleum hydrocarbons and was recommended for selection of biosurfactant producing bacteria in tropical countries with low financial resources.
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Dahalan, Farrah Aini, and Nor Azizah Parmin. "Morphological characterization of gram-positive and gram-negative bacteria from treated latex processing wastewater." Environmental and Toxicology Management 1, no. 2 (August 31, 2021): 32–36. http://dx.doi.org/10.33086/etm.v1i2.2263.
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A preliminary morphological screening and isolation of bacterial colony from latex industrial wastewater was carried out. Bacteria colonies from latex processing wastewater were isolated from a local latex processing industry. It was found that 17 bacterial isolates had been purified grown on nutrient agar under 35˚C. The colonies were then purified and morphologically indicated via Gram staining and motility test. After morphological observation, it was identified that out of 17 isolates, 9 isolates were Gram positive and 8 isolates were Gram negative. There are 11 out of 17 colonies were rod-shaped bacterial colonies, while the other 6 colonies were cocci-shaped bacteria. There were 11 colonies of gliding bacteria, three colonies were non-motile bacteria and the other three colonies were flagellated bacteria. This study is only limited to morphological observation as the main aim of this study was to investigate the potential occurrence of viable growth in treated latex processing wastewater. The bacterial colonies were classified base on their morphological properties shown. This study has classified several genera such as Staphylococcus, Escherichia, Thiobacillus, Arthrobacter and other Genus. The growth curve of 17 isolates studied and the chemical oxygen demand were determined.
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Hadi, Sapto Nugroho, Ida Widiyawati, and Prita Sari Dewi. "ISOLASI BAKTERI LOKAL LAHAN MARGINAL DAN KARAKTERISASI BERDASARKAN LAJU PERTUMBUHAN PADA MEDIA MENGANDUNG BUPROFEZIN." Agrin 22, no. 2 (January 9, 2019): 171. http://dx.doi.org/10.20884/1.agrin.2018.22.2.465.
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Tujuan dari penelitian ini adalah untuk mengisolasi bakteri lokal dari tanah marjinal dari KabupatenBanyumas dan untuk melihat tingkat pertumbuhannya pada media yang mengandung buprofezin 0 ppm, 5 ppm,10 ppm dan 15 ppm. Bakteri diisolasi dari empat sampel tanah dari tanah marginal Desa Srowot, Desa Karangrao,Desa Tanggeran, dan Desa Pagaralang di Kabupaten Banyumas. Populasi bakteri dan koloni makromorfologidiamati untuk menentukan koloni bakteri dominan. Bakteri dominan ditanam pada media NB selama 26 jam untukmelihat kurva pertumbuhan. Bakteri dengan kurva pertumbuhan terbaik kemudian diinkubasi pada media NB yangmengandung buprofezin 0 ppm, 5 ppm, 10 ppm, dan 15 ppm untuk melihat laju pertumbuhan selanjutnya. Variabelyang diamati adalah populasi bakteri tanah, karakter makromorfologi bakteri, laju pertumbuhan bakteri pada mediatanpa pestisida, dan laju pertumbuhan bakteri pada media mengandung buprofezin. Dalam penelitian ini, empatkoloni bakteri dominan, yaitu, SR2, KR1, TG4, dan PA11 diisolasi dari 26 koloni yang tumbuh pada media NAyang mengandung buprofezin 2 ppm. Pengamatan laju pertumbuhan pada media NB tanpa pestisida menunjukkankoloni SR2 memiliki laju pertumbuhan terbaik. Koloni SR2 yang ditumbuhkan pada media NB yang mengandungbuprofezin menunjukkan bahwa koloni dapat beradaptasi dan tumbuh pada konsentrasi buprofezin 5 ppm.Kata kunci: bakteri lahan marginal, Banyumas, buprofezinABSTRACTThe aim of this study is to isolate local bacteria of marginal land from Banyumas regency and to see it’sgrowth rate on media containing buprofezin 0 ppm, 5 ppm, 10 ppm and 15 ppm. Bacteria were isolated from foursoil samples from marginal land of Srowot Village, Karangrao Village, Tanggeran Village, and PagaralangVillage of Banyumas Regency. Bacterial populations and macromorphologic colonies were observed fordetermination of dominant bacterial colonies. The dominant bacteria were grown on NB media for 26 hours tosee the growth curve. Bacteria with the best growth curve then incubated on NB media containing buprofezin 0ppm, 5 ppm, 10 ppm, and 15 ppm to see further growth rate. The variables observed were the population of soilbacteria, the character of the macromorphology of the bacteria, the rate of bacterial growth in the media withoutpesticides, and the rate of bacterial growth in the media containing buprofezin. In this study, four dominantbacterial colonies, namely, SR2, KR1, TG4, and PA11 were isolated from 26 colonies grown on NA mediacontaining buprofezin 2 ppm. Observation of growth rate on NB media without pesticide showed colony of SR2has the best growth rate. Colony SR2 was growth on NB media containing buprofezin showed the colony can adaptand grow at 5 ppm buprofezin concentration.Keyword: Marginal Land Bacteria, Banyumas, Buprofezin
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Nielsen, Elisabet I., Anders Viberg, Elisabeth Löwdin, Otto Cars, Mats O. Karlsson, and Marie Sandström. "Semimechanistic Pharmacokinetic/Pharmacodynamic Model for Assessment of Activity of Antibacterial Agents from Time-Kill Curve Experiments." Antimicrobial Agents and Chemotherapy 51, no. 1 (October 23, 2006): 128–36. http://dx.doi.org/10.1128/aac.00604-06.
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ABSTRACT Dosing of antibacterial agents is generally based on point estimates of the effect, even though bacteria exposed to antibiotics show complex kinetic behaviors. The use of the whole time course of the observed effects would be more advantageous. The aim of the present study was to develop a semimechanistic pharmacokinetic (PK)/pharmacodynamic (PD) model characterizing the events seen in a bacterial system when it is exposed to antibacterial agents with different mechanisms of action. Time-kill curve experiments were performed with a strain of Streptococcus pyogenes exposed to a wide range of concentrations of the following antibiotics: benzylpenicillin, cefuroxime, erythromycin, moxifloxacin, and vancomycin. Bacterial counts were monitored with frequent sampling during the experiment. A simultaneous fit of all data was accomplished. The degradation of the drugs was monitored and corrected for in the model, and a link model was used to account for an effect delay. In the final PK/PD model, the total bacterial population was divided into two subpopulations: one growing drug-susceptible population and one resting insusceptible population. The drug effect was included as an increase of the killing rate of bacteria in the susceptible state, according to a maximum-effect (E max) model. An internal model validation showed that the model was robust and had good predictability. In conclusion, for all drugs, the final PK/PD model successfully described bacterial growth and killing kinetics when the bacteria were exposed to different antibiotic concentrations. The semimechanistic model that was developed might, after further refinement, serve as a tool for the development of optimal dosing strategies for antibacterial agents.
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Nielsen, Elisabet I., Otto Cars, and Lena E. Friberg. "PredictingIn VitroAntibacterial Efficacy across Experimental Designs with a Semimechanistic Pharmacokinetic-Pharmacodynamic Model." Antimicrobial Agents and Chemotherapy 55, no. 4 (January 31, 2011): 1571–79. http://dx.doi.org/10.1128/aac.01286-10.
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ABSTRACTWe have previously described a general semimechanistic pharmacokinetic-pharmacodynamic (PKPD) model that successfully characterized the time course of antibacterial effects seen in bacterial cultures when exposed to static concentrations of five antibacterial agents of different classes. In this PKPD model, the total bacterial population was divided into two subpopulations, one growing drug-susceptible population and one resting drug-insensitive population. The drug effect was included as an increase in the killing rate of the drug-susceptible bacteria with a maximum-effect (Emax) model. The aim of the present study was to evaluate the ability of this PKPD model to describe and predict data fromin vitroexperiments with dynamic concentration-time profiles. Dynamic time-kill curve experiments were performed by using anin vitrokinetic system, where cultures ofStreptococcus pyogeneswere exposed to benzylpenicillin, cefuroxime, erythromycin, moxifloxacin, or vancomycin using different starting concentrations (2 and 16 times the MIC) and elimination conditions (human half-life, reduced half-life, and constant concentrations). The PKPD model was applied, and the observations for the static as well as dynamic experiments were compared to model predictions based on parameter estimation using (i) static data, (ii) dynamic data, and (iii) combined static and dynamic data. Differences in experimental settings between static and dynamic experiments did not affect the growth kinetics of the bacteria significantly. With parameter reestimation, the structure of our previously proposed PKPD model could well characterize the bacterial growth and killing kinetics when exposed to dynamic concentrations with different elimination rates of all five investigated antibiotics. Furthermore, the model with parameter estimates based on data from only the static time-kill curve experiments could predict the majority of the time-kill curves from the dynamic experiments reasonably well. Adding data from dynamic experiments in the estimation improved the model fit for cefuroxime and vancomycin, indicating some differences in sensitivity to experimental conditions among the antibiotics studied.
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George, S. M., A. Métris, and J. Baranyi. "Integrated Kinetic and Probabilistic Modeling of the Growth Potential of Bacterial Populations." Applied and Environmental Microbiology 81, no. 9 (March 6, 2015): 3228–34. http://dx.doi.org/10.1128/aem.04018-14.
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ABSTRACTWhen bacteria are exposed to osmotic stress, some cells recover and grow, while others die or are unculturable. This leads to a viable count growth curve where the cell number decreases before the onset of the exponential growth phase. From such curves, it is impossible to estimate what proportion of the initial cells generates the growth because it leads to an ill-conditioned numerical problem. Here, we applied a combination of experimental and statistical methods, based on optical density measurements, to infer both the probability of growth and the maximum specific growth rate of the culture. We quantified the growth potential of a bacterial population as a quantity composed from the probability of growth and the “suitability” of the growing subpopulation to the new environment. We found that, for all three laboratory media studied, the probability of growth decreased while the “work to be done” by the growing subpopulation (defined as the negative logarithm of their suitability parameter) increased with NaCl concentration. The results suggest that the effect of medium on the probability of growth could be described by a simple shift parameter, a differential NaCl concentration that can be accounted for by the change in the medium composition. Finally, we highlighted the need for further understanding of the effect of the osmoprotectant glycine betaine on metabolism.
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Sukmawati, Sukmawati, Nurul Kusuma Dewi, and Melda Yunita. "The measurement of indole acetic acid from rhizosphere bacteria." JPBIO (Jurnal Pendidikan Biologi) 6, no. 1 (April 29, 2021): 108–15. http://dx.doi.org/10.31932/jpbio.v6i1.872.
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In Indonesia, synthetic chemical fertilizers are generally used to spur plant growth. The use of synthetic chemical fertilizers is known to reduce soil quality, causing resistance to pests and plant diseases. One of the natural potencies that can be used as growth promoters is Indole Acetic Acid (IAA) producing bacteria. The objective of this study was to measure the levels of Indole Acetic Acid (IAA) from the rhizosphere bacterial isolate of green beans which is thought to be able to produce Indole Acetic Acid (IAA). The method used was a descriptive approach, including the isolation of green bean rhizosphere bacteria, measurement of Indole Acetic Acid (IAA) levels in bacterial isolate, and data analysis. Green bean rhizosphere bacterial isolate produced Indole Acetic Acid (IAA) with an indication of a color change after the addition of the Salkowski reagent, and quantitatively the results of calculations in the standard curve equation for Indole Acetic Acid (IAA) obtained a value of Indole Acetic Acid (IAA) levels was 50.91 ppm.Keywords: Indole acetic acid, rhizosphere, bacteria
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Saha, S., P. Karmakar, and Samir Kumar Sil. "CHLOROFORM FRACTION OF PARKIA JAVANICA BARK POSSESSES ANTIBACTERIAL ACTIVITY AGAINST MULTIDRUG RESISTANT GRAM NEGATIVE BACTERIA PREDOMINANTLY FOUND IN SKIN WOUND." Journal of Drug Delivery and Therapeutics 8, no. 5 (September 15, 2018): 184–89. http://dx.doi.org/10.22270/jddt.v8i5.1847.
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Aim: To evaluate the antibacterial activity of Parkia javanica against gram negative MDR bacterial strains which are predominantly found in skin wound. Methods: The 5 different solvent fractions of Parkia javanica were screened for antibacterial activity against gram negative multi drug resistant bacterial strains namely Enterobacter aerugenes, Pseudomonas aeruginosa and Klebsiella pneumonia by serial dilution technique. Growth kinetics study was performed and percentage of ROS production was measured by NBT reduction assay. Results: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were obtained with a range of IC100 0.08-0.31 mg/ml in case of MDR bacterial strains. The lag phase of all extract treated bacteria is extended compared to untreated cells. The normalized % of ROS is increased in presence of Parkia javanica extract. Conclusions: This study suggests that, chloroform fraction of Parkia javanica possesses promising antimicrobial substances which are having activity against MDR bacterial strains and ROS induced bacterial cell damage could be the possible mediator of its antimicrobial activity.
Keywords: Parkia javanica, antibacterial activity, MDR bacterial strains, growth curve, ROS.
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Loy, Alexander, Wolfgang Beisker, and Harald Meier. "Diversity of Bacteria Growing in Natural Mineral Water after Bottling." Applied and Environmental Microbiology 71, no. 7 (July 2005): 3624–32. http://dx.doi.org/10.1128/aem.71.7.3624-3632.2005.
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ABSTRACT Bacterial growth occurs in noncarbonated natural mineral waters a few days after filling and storage at room temperature, a phenomenon known for more than 40 years. Using the full-cycle rRNA approach, we monitored the development of the planktonic bacterial community in a noncarbonated natural mineral water after bottling. Seven 16S rRNA gene libraries, comprising 108 clones in total, were constructed from water samples taken at various days after bottling and from two different bottle sizes. Sequence analyses identified 11 operational taxonomic units (OTUs), all but one affiliated with the betaproteobacterial order Burkholderiales (6 OTUs) or the class Alphaproteobacteria (4 OTUs). Fluorescence in situ hybridization (FISH) was applied in combination with DAPI (4′,6′-diamidino-2-phenylindole) staining, viability staining, and microscopic counting to quantitatively monitor changes in bacterial community composition. A growth curve similar to that of a bacterium grown in a batch culture was recorded. In contrast to the current perception that Gammaproteobacteria are the most important bacterial components of natural mineral water in bottles, Betaproteobacteria dominated the growing bacterial community and accounted for 80 to 98% of all bacteria detected by FISH in the late-exponential and stationary-growth phases. Using previously published and newly designed genus-specific probes, members of the betaproteobacterial genera Hydrogenophaga, Aquabacterium, and Polaromonas were found to constitute a significant proportion of the bacterial flora (21 to 86% of all bacteria detected by FISH). For the first time, key genera responsible for bacterial growth in a natural mineral water were identified by applying molecular cultivation-independent techniques.
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Sun, Yan, Wentao Jiang, Mingzheng Zhang, Lingjun Zhang, Yan Shen, Shengbin Huang, Mingyun Li, et al. "The Inhibitory Effects of Ficin on Streptococcus mutans Biofilm Formation." BioMed Research International 2021 (March 23, 2021): 1–11. http://dx.doi.org/10.1155/2021/6692328.
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To investigate the effects of ficin on biofilm formation of conditionally cariogenic Streptococcus mutans (S. mutans). Biomass and metabolic activity of biofilm were assessed using crystal violet assay, colony-forming unit (CFU) counting, and MTT assay. Extracellular polysaccharide (EPS) synthesis was displayed by SEM imaging, bacteria/EPS staining, and anthrone method while acid production was revealed by lactic acid assay. Growth curve and live/dead bacterial staining were conducted to monitor bacterial growth state in both planktonic and biofilm form. Total protein and extracellular proteins of S. mutans biofilm were analyzed by protein/bacterial staining and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), severally. qRT-PCR was conducted to detect acid production, acid tolerance, and biofilm formation associated genes. Crystal violet assay, CFU counting, and MTT assay showed that the suppression effect of ficin on S. mutans biofilm formation was concentration dependent. 4 mg/mL ficin had significant inhibitory effect on S. mutans biofilm formation including biomass, metabolic activity, EPS synthesis, and lactic acid production ( p < 0.05 ). The growth curves from 0 mg/mL to 4 mg/mL ficin were aligned with each other. There was no significant difference among different ficin groups in terms of live/dead bacterial staining result ( p > 0.05 ). Protein/bacterial staining outcome indicated that ficin inhibit both total protein and biofilm formation during the biofilm development. There were more relatively small molecular weight protein bands in extracellular proteins of 4 mg/mL ficin group when compared with the control. Generally, ficin could inhibit biofilm formation and reduce cariogenic virulence of S. mutans effectively in vitro; thus, it could be a potential anticaries agent.
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de Oliveira, Mara Elisa Soares, Fabiano Silva Fernandes, Murilo A. Glória Junior, Alvaro Soares de Oliveira, Reginaldo Gonçalves Mafia, and Maria Alves Ferreira. "Temporal Analysis of Bacterial Leaf Blight in Clonal Eucalyptus Plantations in Brazil." Forests 10, no. 10 (September 25, 2019): 839. http://dx.doi.org/10.3390/f10100839.
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Bacterial leaf blight is an important disease in Eucalyptus spp. plantations since it can cause defoliation, affecting plant development. A better understanding of the disease epidemiology is important for its control. Thus, the aim of this study was to analyze bacterial leaf blight temporal progress in the initial establishment in the field of different eucalyptus clones. It also targeted to correlate the incidence and area under the disease-progress curve (AUDPC), with variables related to growth and meteorological data. Bacterial leaf blight progress curves were analyzed based on incidence and carried out AUDPC calculation. Pearson’s coefficient was used to verify the correlations between bacterial leaf blight incidence and AUDPC with clone initial growth and meteorological factors. Gompertz or Logistic models were the best adjustment to data, according to the assessed clones. A difference in AUDPC was observed between clones regarding bacterial leaf blight incidence during the assessment period. Clones were divided into three groups with different tolerance levels. A negative correlation was observed between bacterial leaf blight incidence, AUDPC, and growth variables of clones. During the assessment period, average air temperature, rainfall, and air relative humidity favored disease incidence. The clones A469, VM01, and 373 were the most tolerant to the disease.
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Ahmad, Rizwan, Muhammad Mahmood-ul Hassan, Muhammad Yasin, and Vishandas Suthor. "Cadmium Tolerance and Bioremediation Potential of Bacteria Isolated from Soils Irrigated with Untreated Industrial Effluent." Biological Sciences - PJSIR 58, no. 2 (August 24, 2015): 65–71. http://dx.doi.org/10.52763/pjsir.biol.sci.58.2.2015.65.71.
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The present study was aimed to investigate the Cd tolerance of bacteria isolated from municipal effluent irrigated soils. Thirty bacterial strains were isolated and screened for their Cd+ tolerance by growing on nutrient agar plates amended with varying amount of Cd+. Out of them four bacteria (GS2, GS5, GS10 and GS20) were found highly Cd tolerant (600 ppm Cd). The minimum inhibitory concentration of Cd+ was found 200 ppm. The isolates showed optimum growth at 30 °C and pH 7.5-8.5. Growth curve study against different concentrations of Cd (0-600 ppm) revealed that GS2 was more tolerant among selected strains showing only 33% reduction in growth compared to 64% by GS5 and 77% by both GS10 and GS20 at 600 ppm Cd. Inoculation of maize seeds with Cd tolerant bacteria for root elongation demonstrated up to 1.7 fold increase in root elongation (in the absence of Cd) and up to 1.5 fold (in the presence of 50 ppm Cd) compared to the un-inoculated plants. The results of the study revealed that the bacterial isolates exhibiting great Cd tolerance and growth promoting activity can be potential candidates for bioremediation of metal contaminated soils and wastewaters.
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Peleg, Micha, and Mark D. Normand. "Modeling of Fungal and Bacterial Spore Germination under Static and Dynamic Conditions." Applied and Environmental Microbiology 79, no. 21 (August 30, 2013): 6765–75. http://dx.doi.org/10.1128/aem.02521-13.
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ABSTRACTIsothermal germination curves, sigmoid and nonsigmoid, can be described by a variety of models reminiscent of growth models. Two of these, which are consistent with the percent of germinated spores being initially zero, were selected: one, Weibullian (or “stretched exponential”), for more or less symmetric curves, and the other, introduced by Dantigny's group, for asymmetric curves (P. Dantigny, S. P.-M. Nanguy, D. Judet-Correia, and M. Bensoussan, Int. J. Food Microbiol. 146:176–181, 2011). These static models were converted into differential rate models to simulate dynamic germination patterns, which passed a test for consistency. In principle, these and similar models, if validated experimentally, could be used to predict dynamic germination from isothermal data. The procedures to generate both isothermal and dynamic germination curves have been automated and posted as freeware on the Internet in the form of interactive Wolfram demonstrations. A fully stochastic model of individual and small groups of spores, developed in parallel, shows that when the germination probability is constant from the start, the germination curve is nonsigmoid. It becomes sigmoid if the probability monotonically rises from zero. If the probability rate function rises and then falls, the germination reaches an asymptotic level determined by the peak's location and height. As the number of individual spores rises, the germination curve of their assemblies becomes smoother. It also becomes more deterministic and can be described by the empirical phenomenological models.
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Hunt, K. M., J. Preuss, C. Nissan, C. A. Davlin, J. E. Williams, B. Shafii, A. D. Richardson, M. K. McGuire, L. Bode, and M. A. McGuire. "Human Milk Oligosaccharides Promote the Growth of Staphylococci." Applied and Environmental Microbiology 78, no. 14 (May 4, 2012): 4763–70. http://dx.doi.org/10.1128/aem.00477-12.
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ABSTRACTHuman milk oligosaccharides (HMO), which constitute a major component of human milk, promote the growth of particular bacterial species in the infant's gastrointestinal tract. We hypothesized that HMO also interact with the bacterial communities present in human milk. To test this hypothesis, two experiments were conducted. First, milk samples were collected from healthy women (n= 16); culture-independent analysis of the bacterial communities was performed, HMO content was analyzed, and the relation between these factors was investigated. A positive correlation was observed between the relative abundance ofStaphylococcusand total HMO content (r= 0.66). In a follow-up study, we conducted a series ofin vitrogrowth curve experiments utilizingStaphylococcus aureusorStaphylococcus epidermidisand HMO isolated from human milk. HMO exhibited stimulatory effects on bacterial growth under various nutritional conditions. Analysis of culture supernatants from these experiments revealed that HMO did not measurably disappear from the culture medium, indicating that the growth-enhancing effects were not a result of bacterial metabolism of the HMO. Instead, stimulation of growth caused greater utilization of amino acids in minimal medium. Collectively, the data provide evidence that HMO may promote the growth ofStaphylococcusspecies in the lactating mammary gland.
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Li, Hui Rong, Wei Ming Liu, Shi Jing Cheng, and Yang Jiang. "Effect of Lithium on Growth Process of Environmental Microorganism by Microcalorimetry and SEM." Advanced Materials Research 955-959 (June 2014): 445–49. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.445.
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Bacillus thuringiensis (BT) was the typical environmental microorganism.To explore the environmental behavior of lithium, the growth metabolism of BT under Li+ was investigated by microcalorimetry. The power-time curve showed the growth metabolic power-time curve of BT was divided into the bacterial growth phase and sporulation process. Lithium at 0.1-12mmol L-1 revealed no obvious effect to the bacterial growth phase of BT . Li+ at 0.1-4mmol L-1 stimulated the sporulation production and Li+ at 12-16mmol L-1 inhibited that respectively. While the time for initiation to produce sporulation was not influenced. However, the time for initiation to produce sporulation was earlier than the control induced by 8 mmol L-1 of Li+. The interest turning point of microcalorimetric result was confirmed by the following SEM detection. Besides the proof on environmental behavior of lithium, present results may bring related information for BT spores biological engineering transformation.
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Lewis, Richard A., Colin R. Bignell, Wei Zeng, Anthony C. Jones, and Christopher M. Thomas. "Chromosome loss from par mutants of Pseudomonas putida depends on growth medium and phase of growth." Microbiology 148, no. 2 (February 1, 2002): 537–48. http://dx.doi.org/10.1099/00221287-148-2-537.
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The proteins encoded by chromosomal homologues of the parA and parB genes of many bacterial plasmids have been implicated in chromosome partitioning. Unlike their plasmid counterparts, mutant phenotypes produced by deleting these genes have so far been elusive or weakly expressed, except during sporulation. Here the properties of Pseudomonas putida strains with mutations in parA and parB are described. These mutants do not give rise to elevated levels of anucleate bacteria when grown in rich medium under standard conditions. However, in M9-minimal medium different parA and parB mutations gave between 5 and 10% anucleate cells during the transition from exponential phase to stationary phase. Comparison of the DNA content of bacteria at different stages of the growth curve, in batch culture in L-broth and in M9-minimal medium, suggests that the par genes are particularly important for chromosome partitioning when cell division reduces the chromosome copy number per cell from two to one. This transition occurs in P. putida during the entry into stationary phase in M9-minimal medium, but not in L-broth. It is proposed that the partition apparatus is important to ensure proper chromosome segregation primarily when the bacteria are undergoing cell division in the absence of ongoing DNA replication.
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Sánchez-Clemente, Rubén, M. Isabel Guijo, Juan Nogales, and Rafael Blasco. "Carbon Source Influence on Extracellular pH Changes along Bacterial Cell-Growth." Genes 11, no. 11 (October 30, 2020): 1292. http://dx.doi.org/10.3390/genes11111292.
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The effect of initial pH on bacterial cell-growth and its change over time was studied under aerobic heterotrophic conditions by using three bacterial strains: Escherichia coli ATCC 25922, Pseudomonas putida KT2440, and Pseudomonas pseudoalcaligenes CECT 5344. In Luria-Bertani (LB) media, pH evolved by converging to a certain value that is specific for each bacterium. By contrast, in the buffered Minimal Medium (MM), pH was generally more stable along the growth curve. In MM with glucose as carbon source, a slight acidification of the medium was observed for all strains. In the case of E. coli, a sudden drop in pH was observed during exponential cell growth that was later recovered at initial pH 7 or 8, but was irreversible below pH 6, thus arresting further cell-growth. When using other carbon sources in MM at a fixed initial pH, pH changes depended mainly on the carbon source itself. While glucose, glycerol, or octanoate slightly decreased extracellular pH, more oxidized carbon sources, such as citrate, 2-furoate, 2-oxoglutarate, and fumarate, ended up with the alkalinization of the medium. These observations are in accordance with pH change predictions using genome-scale metabolic models for the three strains, thus revealing the metabolic reasons behind pH change. Therefore, we conclude that the composition of the medium, specifically the carbon source, determines pH change during bacterial growth to a great extent and unravel the main molecular mechanism behind this phenotype. These findings pave the way for predicting pH changes in a given bacterial culture and may anticipate the interspecies interactions and fitness of bacteria in their environment.
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Weinrich, Lauren A., Eugenio Giraldo, and Mark W. LeChevallier. "Development and Application of a Bioluminescence-Based Test for Assimilable Organic Carbon in Reclaimed Waters." Applied and Environmental Microbiology 75, no. 23 (October 9, 2009): 7385–90. http://dx.doi.org/10.1128/aem.01728-09.
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ABSTRACT Assimilable organic carbon (AOC) is an important parameter governing the growth of heterotrophic bacteria in drinking water. Despite the recognition that variations in treatment practices (e.g., disinfection, coagulation, selection of filter media, and watershed protection) can have dramatic impacts on AOC levels in drinking water, few water utilities routinely measure AOC levels because of the difficulty of the method. To simplify the method, the Pseudomonas fluorescens P-17 and Spirillum sp. strain NOX test bacteria were mutagenized by using luxCDABE operon fusion and inducible transposons to produce bioluminescent strains. The growth of these strains can easily be monitored with a programmable luminometer to determine the maximum cell yield via luminescence readings, and these values can be fitted to the classical Monod growth curve to determine bacterial growth kinetics and the maximum growth rate. Standard curves using acetate carbon (at concentrations ranging from 0 to 1,000 μg/liter) resulted in coefficients of determination (r 2) between luminescence units and acetate carbon levels of 0.95 for P-17 and 0.89 for NOX. The bioluminescence test was used to monitor reclaimed water, in which average AOC levels range between 150 and 1,400 μg/liter acetate carbon equivalents. Comparison of the conventional AOC assay and the bioluminescent assay produced an r 2 of 0.92.
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Tajuddin, Z. M. F., and A. Rashid Azura. "Bacillus megaterium sp. as Degradation Agent for Biodegradable Natural Rubber Latex Films." Advanced Materials Research 626 (December 2012): 813–17. http://dx.doi.org/10.4028/www.scientific.net/amr.626.813.
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Degradation for biodegradable natural rubber (NRL) films by Bacillus megaterium sp. is investigated. A common soil bacterium, Bacillus megaterium sp. is one of the largest eubacteria. This bacterium has large potential in degradation process for biodegradable natural rubber latex film. Specified method is used to cultivate the bacteria using suitable media. The growth of bacteria is studied through optical density and dry weight as a function of time. The optical density at specific wavelength with different stages of bacterial growth is used to determine their mid-log growth phase of the cell. The optimum time achieved to insert NRL films is between 17 to 20 hours of incubation period. Growth curve of Bacillus megaterium sp. gives an equation of Y=2.3401X. The biodegradation behaviour of Bacillus megaterium sp. is further investigated to access the viability as accelerating media for biodegradation of NRL films.
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Bazyar, Hanieh, Linya Xu, Hendrik Jan de Vries, Slawomir Porada, and Rob G. H. Lammertink. "Application of liquid-infused membranes to mitigate biofouling." Environmental Science: Water Research & Technology 7, no. 1 (2021): 68–77. http://dx.doi.org/10.1039/d0ew00203h.
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Tamiyakul, Hathaichanok, Somboon Tanasupawat, Stephan Thierry Dubas, and Warangkana Warisnoicharoen. "Antibacterial Potential of Silver Nanoparticles Capped with Poly(4-styrenesulfonic acid-co-maleic acid) Polymer." Advanced Materials Research 1088 (February 2015): 64–68. http://dx.doi.org/10.4028/www.scientific.net/amr.1088.64.
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Antibacterial potential of metallic silver nanoparticles (AgNPs) is considered to be influenced by their size and stability. In this study, the stable AgNPs capped with poly (4-styrenesulfonic acid-co-maleic acid) or PSSMA were successfully synthesized by using a chemical reduction method. The PSSMA-stabilized AgNPs (PSSMA-AgNPs) were characterized and tested for antibacterial activity against eight bacterial strains. Transmission electron microscopic studies showed that PSSMA-AgNPs were monodisperse spherical particles with an average size of 5.21 nm. From bacterial growth curve studies, PSSMA-AgNPs exhibited an antibacterial effect on Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Staphylococcus aureus ATCC 6538p, Staphylococcus aureus ATCC 43300, Staphylococcus epidermidis ATCC 12228 and Bacillus subtilis ATCC 6633) and Gram-negative bacteria (Escherichia coli ATCC 25922, Enterobacter aerogenes ATCC 13048 and Pseudomonas aeruginosa ATCC 27853). Moreover, the Gram-negative bacteria were found to be more susceptible to the AgNPs.
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Firsov, Alexander A., Deborah Gilbert, Kenneth Greer, Yury A. Portnoy, and Stephen H. Zinner. "Comparative Pharmacodynamics and Antimutant Potentials of Doripenem and Imipenem with Ciprofloxacin-Resistant Pseudomonas aeruginosa in anIn VitroModel." Antimicrobial Agents and Chemotherapy 56, no. 3 (December 27, 2011): 1223–28. http://dx.doi.org/10.1128/aac.05964-11.
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ABSTRACTTo compare the antipseudomonal efficacy of doripenem and imipenem as well as their abilities to restrict the enrichment of resistantPseudomonas aeruginosa, multiple-dosing regimens of each drug were simulated at comparable values of the cumulative percentages of a 24-h period that the drug concentration exceeds the MIC under steady-state pharmacokinetic conditions (T>MIC) and ratios of the 24-hour area under the curve (AUC24) to the MIC. Three clinical isolates of ciprofloxacin-resistantP. aeruginosa(MIC of doripenem, 1 μg/ml; MICs of imipenem, 1, 2, and 2 μg/ml) were exposed to thrice-daily doripenem or imipenem for 3 days at AUC24/MIC ratios of from 50 to 170 h (doripenem) and from 30 to 140 h (imipenem). The antimicrobial effects for susceptible and resistant subpopulations of bacteria were expressed by the areas between control growth and time-kill curves (IEs) and areas under the bacterial mutant concentration curves (AUBCMs), respectively. With each antibiotic, theIEand AUBCMversus log AUC24/MIC relationships were bacterial strain independent. At similar AUC24/MIC ratios, doripenem was slightly less efficient than imipenem against susceptible and resistant subpopulations of bacteria. However, doripenem appeared to be somewhat more efficient than imipenem at clinically achievable AUC24s related to the means of the MICs for the three studied strains and had higher antimutant potentials for two of the three strains.
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Huang, Yin, and Charles N. Haas. "Quantification of the Relationship between Bacterial Kinetics and Host Response for Monkeys Exposed to AerosolizedFrancisella tularensis." Applied and Environmental Microbiology 77, no. 2 (November 29, 2010): 485–90. http://dx.doi.org/10.1128/aem.01190-10.
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ABSTRACTFrancisella tularensiscan be disseminated via aerosols, and once inhaled, only a few microorganisms may result in tularemia pneumonia. Effective responses to this threat depend on a thorough understanding of the disease development and pathogenesis. In this study, a class of time-dose-response models was expanded to describe quantitatively the relationship between the temporal probability distribution of the host response and thein vivobacterial kinetics. An extensive literature search was conducted to locate both the dose-dependent survival data and thein vivobacterial count data of monkeys exposed to aerosolizedF. tularensis. One study reporting responses of monkeys to four different sizes of aerosol particles (2.1, 7.5, 12.5, and 24.0 μm) of the SCHU S4 strain and three studies involving fivein vivogrowth curves of various strains (SCHU S4, 425, and live vaccine strains) initially delivered to hosts in aerosol form (1 to 5 μm) were found. The candidate models exhibited statistically acceptable fits to the time- and dose-dependent host response and provided estimates for the bacterial growth distribution. The variation pattern of such estimates with aerosol size was found to be consistent with the reported pathophysiological and clinical observations. The predicted growth curve for 2.1-μm aerosolized bacteria was highly consistent with the available bacterial count data. This is the first instance in which the relationship between thein vivogrowth ofF.tularensisand the host response can be quantified by mechanistic mathematical models.
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Paccotti, Niccolò, Francesco Boschetto, Satoshi Horiguchi, Elia Marin, Alessandro Chiadò, Chiara Novara, Francesco Geobaldo, Fabrizio Giorgis, and Giuseppe Pezzotti. "Label-Free SERS Discrimination and In Situ Analysis of Life Cycle in Escherichia coli and Staphylococcus epidermidis." Biosensors 8, no. 4 (December 15, 2018): 131. http://dx.doi.org/10.3390/bios8040131.
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Surface enhanced Raman spectroscopy (SERS) has been proven suitable for identifying and characterizing different bacterial species, and to fully understand the chemically driven metabolic variations that occur during their evolution. In this study, SERS was exploited to identify the cellular composition of Gram-positive and Gram-negative bacteria by using mesoporous silicon-based substrates decorated with silver nanoparticles. The main differences between the investigated bacterial strains reside in the structure of the cell walls and plasmatic membranes, as well as their biofilm matrix, as clearly noticed in the corresponding SERS spectrum. A complete characterization of the spectra was provided in order to understand the contribution of each vibrational signal collected from the bacterial culture at different times, allowing the analysis of the bacterial populations after 12, 24, and 48 h. The results show clear features in terms of vibrational bands in line with the bacterial growth curve, including an increasing intensity of the signals during the first 24 h and their subsequent decrease in the late stationary phase after 48 h of culture. The evolution of the bacterial culture was also confirmed by fluorescence microscope images.
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Sivashankari, L., S. K. Rajkishore, A. Lakshmanan, K. S. Subramanian, and M. Praghadeesh. "Bio-safety assessment of nanozeolites of varying size and doses on soil beneficial microorganisms." Journal of Environmental Biology 42, no. 4(SI) (July 1, 2021): 1181–90. http://dx.doi.org/10.22438/jeb/42/4(si)/mrn-1561a.
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Aim: To evaluate the toxic effects of nano-zeolites on soil beneficial microorganisms. Methodology: This study involved dry milling of zeolites at varying parameters to obtain dry-milled zeolites of four size regimes such as 10-100 nm, 200-400 nm, 500-1000 nm and 1000-2000 nm that were tested at incremental concentrations such as 100 ppm, 1000 ppm and 2000 ppm along with control on various soil beneficial microorganisms. Three replications were done for each treatment with factorial completely randomized design. The poison food technique, growth curve assessment followed by cytotoxicity and genotoxicity studies on all four bacterial genera treated with zeolites of varying sizes and doses were undertaken. The effects of zeolite on average linear growth rate (ALGR) of biocontrol agent, Trichoderma viride were also studied. Results: The effect of zeolites tested on four bacterial genera viz. Azotobacter chroococcum, Rhizobium leguminosarum, Bacillus megaterium and Pseudomonas fluorescens using poison food technique and growth curve revealed that zeolites regardless of size or concentration had positively influenced the growth dynamics of all four bacteria tested. The effect of zeolite on average linear growth rate (ALGR) of Trichoderma viride also indicated that incremental dose of zeolite had a positive effect. Lactose dehydrogenase revealed that 2000 ppm nano-zeolite exhibited cytotoxic effects on soil beneficial micro-organisms tested. On the other hand, comet assay demonstrated no quantifiable DNA damage in nano-zeolite treated cells in comparison to control cultures. Interpretation: This study unequivocally demonstrated that zeolites of size greater than 200-400 nm, irrespective of doses even up to 2000 ppm are quite safe for soil beneficial microbes.
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Choi, Soo-Hyoen, Yong-Seok Jang, Jong-Hwa Jang, Tae-Sung Bae, Sook-Jeong Lee, and Min-Ho Lee. "Enhanced antibacterial activity of titanium by surface modification with polydopamine and silver for dental implant application." Journal of Applied Biomaterials & Functional Materials 17, no. 3 (July 2019): 228080001984706. http://dx.doi.org/10.1177/2280800019847067.
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Background: Biofilm formation and microbial colonization on the surface of implant devices may cause dental caries and peri-implantitis. Therefore, various surface treatments have been developed to improve the antibacterial activity of titanium implant. Methods: Silver-loaded polydopamine coating was formed by immersing pure titanium in dopamine hydrochloride/HCl buffer solution for 24 h in 50 mL silver nitrate solutions with different concentrations for 30 min. Microbial growth inhibition and microbial growth curve analyses for bacterial solutions of Streptococcus mutans and Porphyromonas gingivalis incubated with the specimens were respectively conducted by counting the numbers of colonies on agar solid medium and by measuring absorbance using enzyme-linked immunosorbent assay reader. Results: Silver nanoparticles were uniformly distributed over the whole surface of the polydopamine and silver-coated titanium specimens. The numbers of microbial colonies for both bacteria cultured with surface-modified titanium were significantly lower than those cultured with uncoated titanium. When Streptococcus mutans and Porphyromonas gingivalis were cultured with surface-modified titanium, the lag phase of the growth curves for both bacteria was continually maintained, whereas the lag phase for Streptococcus mutans and Porphyromonas gingivalis changed to exponential phase after 9 and 15 h, respectively, when both bacteria were cultured with uncoated titanium. Conclusion: It was confirmed that the coating of polydopamine and silver on the surface of titanium effectively retards the microbial growth, which can cause the formation of biofilm and pathogenesis of gum disease in the mouth.
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Chen, Wu, Fu Xiang, Jie Fu, Qiang Wang, Wenjun Wang, Qingfu Zeng, and Longjiang Yu. "Identification and Phylogenetic Analysis of New Sulfate-Reducing Bacteria Isolated from Oilfield Samples." Zeitschrift für Naturforschung C 64, no. 3-4 (April 1, 2009): 260–66. http://dx.doi.org/10.1515/znc-2009-3-418.
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Microbiologically influenced corrosion (MIC) caused by sulfate-reducing bacteria (SRB) has been investigated in an oilfield injection water system. Strain CW-01 was isolated from an oilfield and strain CW-04 was isolated from biofilm dirt of pipeline walls. The strains were facultative anaerobes, non-motile, Gram-positive, pole flagellum, and spore-forming curved rods. The growth was observed over the temperature range 20-70 °C. Strain CW-01 grew optimally at 37 °C. The pH range for growth was 3.0-11, optimal at pH 6.0. Strain CW-04 grew optimally at 48 °C. The pH range for growth was 3.0-10, optimal at pH 7.2. The strains grew at a very broad range of salt concentrations. Optimal growth was observed with 1.5 g/L NaCl for strain CW-01 and 0.7 g/L NaCl for strain CW-04. The strains showed most similarity in physiological characteristics, except for acetone and saccharose. Analysis of the 16S rDNA sequences allowed strains CW-01 and CW-04 to be classified into the genus Desulfotomaculum. The corrosion speciality of the strains had been comparatively investigated. Especially SRB’s growth curve, bearable oxygen capability, drug fastness and corrosion rate had been analyzed. The results showed that it is difficult to prevent bacterial corrosion caused by these two strains.
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Ba, Boubakar B., Hala Feghali, Corinne Arpin, Marie-Claude Saux, and Claudine Quentin. "Activities of Ciprofloxacin and Moxifloxacin against Stenotrophomonas maltophilia and Emergence of Resistant Mutants in an In Vitro Pharmacokinetic-Pharmacodynamic Model." Antimicrobial Agents and Chemotherapy 48, no. 3 (March 2004): 946–53. http://dx.doi.org/10.1128/aac.48.3.946-953.2004.
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ABSTRACT A two-compartment in vitro pharmacokinetic-pharmacodynamic model, with full computer-controlled devices, was used to accurately simulate human plasma pharmacokinetic profiles after multidose oral regimens of ciprofloxacin (750 mg every 12 h) and moxifloxacin (400 mg every 24 h) during 48 h. Pharmacodynamics of these drugs was investigated against three quinolone-susceptible strains of Stenotrophomonas maltophilia (MICs of ciprofloxacin and moxifloxacin of 0.5 to 2 and 0.0625 to 0.5 μg/ml, respectively). The first dose of ciprofloxacin and moxifloxacin reduced the bacterial count by 1 and 2 log CFU/ml, respectively, prior to a bacterial regrowth that reached the plateau value of the growth control curve at 13 to 24 h versus 24 to 36 h and persisted despite repeated administration of both drugs. The surviving bacterial cells were quinolone-resistant mutants (2 to 128 times the MIC) that exhibited cross-resistance to unrelated antibiotics. Their antibiotic resistance probably resulted from the overproduction of different multidrug resistance efflux system(s). C max/MIC and area under the concentration-time curve from 0 to 24 h (AUC0-24)/MIC values were at least threefold higher for moxifloxacin than for ciprofloxacin. Moreover, integral parameters of ciprofloxacin and moxifloxacin, in particular the area under the killing and regrowth curve from 0 to 48 h (AUBC0-48, 342.3 to 401.3 versus 295.2 to 378.7 h × log CFU/ml, respectively) and the area between the control growth curve and the killing and regrowth curve from 0 to 48 h (ABBC0-48, 40.4 to 101.1 versus 72.9 to 144.7 h × log CFU/ml, respectively), demonstrated a better antibacterial effect of moxifloxacin than ciprofloxacin on S. maltophilia. However, selection of resistant mutants by both fluoroquinolones, although delayed with moxifloxacin, emphasizes the need to use maximal dosages and combined therapy in the treatment of systemic S. maltophilia infections.
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Roszkowiak, Justyna, Paweł Jajor, Grzegorz Guła, Jerzy Gubernator, Andrzej Żak, Zuzanna Drulis-Kawa, and Daria Augustyniak. "Interspecies Outer Membrane Vesicles (OMVs) Modulate the Sensitivity of Pathogenic Bacteria and Pathogenic Yeasts to Cationic Peptides and Serum Complement." International Journal of Molecular Sciences 20, no. 22 (November 8, 2019): 5577. http://dx.doi.org/10.3390/ijms20225577.
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The virulence of bacterial outer membrane vesicles (OMVs) contributes to innate microbial defense. Limited data report their role in interspecies reactions. There are no data about the relevance of OMVs in bacterial-yeast communication. We hypothesized that model Moraxella catarrhalis OMVs may orchestrate the susceptibility of pathogenic bacteria and yeasts to cationic peptides (polymyxin B) and serum complement. Using growth kinetic curve and time-kill assay we found that OMVs protect Candida albicans against polymyxin B-dependent fungicidal action in combination with fluconazole. We showed that OMVs preserve the virulent filamentous phenotype of yeasts in the presence of both antifungal drugs. We demonstrated that bacteria including Haemophilus influenza, Acinetobacter baumannii, and Pseudomonas aeruginosa coincubated with OMVs are protected against membrane targeting agents. The high susceptibility of OMV-associated bacteria to polymyxin B excluded the direct way of protection, suggesting rather the fusion mechanisms. High-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV) and zeta-potential measurement revealed a high sequestration capacity (up to 95%) of OMVs against model cationic peptide accompanied by an increase in surface electrical charge. We presented the first experimental evidence that bacterial OMVs by sequestering of cationic peptides may protect pathogenic yeast against combined action of antifungal drugs. Our findings identify OMVs as important inter-kingdom players.
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Huang, Lihan. "Simulation and evaluation of different statistical functions for describing lag time distributions of a bacterial growth curve." Microbial Risk Analysis 1 (January 2016): 47–55. http://dx.doi.org/10.1016/j.mran.2015.08.002.
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Alzabt, A. M., and Y. Rukayadi. "Antibacterial activity of taro [Colocasia esculenta (L.) Schott] leaves extract against foodborne pathogens and its effect on microbial population in raw chicken meat." Food Research 5, no. 2 (April 25, 2021): 401–9. http://dx.doi.org/10.26656/fr.2017.5(2).523.
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Chicken meat is one of the most consumed animal products worldwide. It is a favourable medium for bacterial growth due to its high moisture content and nitrogenous compounds. The growth of foodborne pathogens in food products can cause food poisoning and foodborne illness. Chemical preservatives act to restrict microbial growth which causes deterioration and spoilage of chicken meat and chicken meat products. Chemical preservatives, however, are not preferred nowadays due to consumer perception and their residual effect on the human body. Therefore, the interest in the development of plantbased bio preservatives as a natural alternative to chemical preservatives is increasingly gaining attention. This study aimed to evaluate the antimicrobial activity of taro [Colocasia esculenta (L.) Schott] leaves extract against foodborne pathogens, including Escherichia coli ATCC 43895, Listeria monocytogenes ATCC 19112, Salmonella enterica serovar Typhimurium ATCC 14028, and Staphylococcus aureus ATCC 29737, as well as its effect on microbial population in chicken meat at different concentrations and exposure times. Taro leaves powder was extracted by maceration methods using ethanol as a solvent. The crude extract was tested for antibacterial activity by means of disc diffusion assay (DDA), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill curve analysis. The effects of the extract on microbial population were evaluated at different concentrations, exposure times and storage temperatures. The results showed the inhibition zone of the extract against tested bacterial ranged from 9.5±0.3 mm to 11.6±0.2 mm. The extract can inhibit the growth and kill the tested bacteria with MIC and MBC of 2.50 and 5.00 mg/mL, respectively. The time-kill curve analysis demonstrated that the extract can completely kill the tested bacteria at 4× MIC for 0.5 hrs. Approximately, 5% of the extract could reduce all the microbial population in chicken meat samples with an exposure time of 30 mins. The result suggested that taro leaves extract (TLE) can be integrated into the food system as a natural food preservative.
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Manduru, M., L. B. Mihm, R. L. White, L. V. Friedrich, P. A. Flume, and J. A. Bosso. "Comparative bactericidal activity of ceftazidime against isolates of Pseudomonas aeruginosa as assessed in an in vitro pharmacodynamic model versus the traditional time-kill method." Antimicrobial Agents and Chemotherapy 41, no. 11 (November 1997): 2527–32. http://dx.doi.org/10.1128/aac.41.11.2527.
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Bactericidal activity, historically assessed by in vitro tests which employ fixed drug concentrations, may also be evaluated in in vitro pharmacodynamic models in which in vivo pharmacokinetics and bacterial growth conditions can be simulated. However, systematic comparisons between the two methods are lacking. We evaluated the bactericidal activities of ceftazidime, at two different concentration/MIC ratios (C/MICs), against 10 clinical isolates of Pseudomonas aeruginosa in a two-compartment model with continuous-infusion conditions and a 2-h half-life. These values were compared to those determined by traditional 24-h time-kill (TTK) methods at the same C/MICs. Bactericidal activities were compared by using area under the colony count-time curves. Antibiotic exposure (area under the drug concentration-time curve) was also evaluated. Although bactericidal activity appeared greater by the TTK method (P = 0.05), when it was normalized for drug exposure, these differences disappeared (P = 0.2). This disparity was likely due to differences in drug exposure in the TTK method and in the peripheral compartment of the model (site of bacteria) over the first 8 h of the experiment, during which the antibiotic accumulated to target concentrations. This suggests that the bactericidal effects with constant antibiotic concentrations are similar in the two methods; however, this may not hold true with fluctuating drug concentrations. Further, results from the pharmacodynamic model may theoretically be more relevant, as in vivo pharmacokinetics and bacterial growth conditions call be more faithfully simulated.