Artículos de revistas: "L-form bacteria"

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Errington, Jeff. "L-form bacteria, cell walls and the origins of life". Open Biology 3, n.º 1 (enero de 2013): 120143. http://dx.doi.org/10.1098/rsob.120143.

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The peptidoglycan wall is a defining feature of bacterial cells and was probably already present in their last common ancestor. L-forms are bacterial variants that lack a cell wall and divide by a variety of processes involving membrane blebbing, tubulation, vesiculation and fission. Their unusual mode of proliferation provides a model for primitive cells and is reminiscent of recently developed in vitro vesicle reproduction processes. Invention of the cell wall may have underpinned the explosion of bacterial life on the Earth. Later innovations in cell envelope structure, particularly the emergence of the outer membrane of Gram-negative bacteria, possibly in an early endospore former, seem to have spurned further major evolutionary radiations. Comparative studies of bacterial cell envelope structure may help to resolve the early key steps in evolutionary development of the bacterial domain of life.

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Errington, Jeff, Katarzyna Mickiewicz, Yoshikazu Kawai y Ling Juan Wu. "L-form bacteria, chronic diseases and the origins of life". Philosophical Transactions of the Royal Society B: Biological Sciences 371, n.º 1707 (5 de noviembre de 2016): 20150494. http://dx.doi.org/10.1098/rstb.2015.0494.

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The peptidoglycan cell wall is widely conserved across the bacterial domain, suggesting that it appeared early in the evolution of bacteria. It is normally essential but under certain conditions wall-deficient or ‘L-form’ bacteria can be isolated. In Bacillus subtilis this normally requires two genetic changes. The first, exemplified by mutations shutting down wall precursor synthesis, works by increasing membrane synthesis. This promotes the unusual form of proliferation used by L-forms, involving a range of relatively disorganized membrane blebbing or vesiculation events. The secondary class of mutations probably work by relieving oxidative stress that L-forms may incur due to their unbalanced metabolism. Repression or inhibition of cell wall precursor synthesis can stimulate the L-form transition in a wide range of bacteria, of both Gram-positive and -negative lineages. L-forms are completely resistant to most antibiotics working specifically on cell wall synthesis, such as penicillins and cephalosporins, consistent with the many reports of their involvement in various chronic diseases. They are potentially important in biotechnology, because lack of a wall can be advantageous in a range of production or strain improvement applications. Finally, L-forms provide an interesting model system for studying early steps in the evolution of cellular life. This article is part of the themed issue ‘The new bacteriology’.

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Daulagala, PWHKP y EJ Allan. "Induction of L-form Bacteria from Bacillus thuringiensis". Ceylon Journal of Science (Biological Sciences) 41, n.º 2 (3 de abril de 2013): 137. http://dx.doi.org/10.4038/cjsbs.v41i2.5383.

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Osawa, Masaki y Harold P. Erickson. "L form bacteria growth in low-osmolality medium". Microbiology 165, n.º 8 (1 de agosto de 2019): 842–51. http://dx.doi.org/10.1099/mic.0.000799.

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Grichko, Varvara P. y Bernard R. Glick. "The potential of L-form bacteria in biotechnology". Canadian Journal of Chemical Engineering 77, n.º 5 (octubre de 1999): 973–77. http://dx.doi.org/10.1002/cjce.5450770526.

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Mokhtar, Norfaniza, Zhameir Shafiq Mohd Ilias, Husnul Azan Tajarudin y Megat Azmi Megat Johari. "Optimization of HCO₃^-Production Reflect to CaСo₃ Precipitation for Self-Healing by Bacillus sphaericus". Applied Mechanics and Materials 802 (octubre de 2015): 549–54. http://dx.doi.org/10.4028/www.scientific.net/amm.802.549.

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Bacteria are able to perform metabolic activities which promote the precipitation of calcium carbonate in the form of calcite. Bacillus Sphaericus was used in this study, which is an ureolytic bacteria that can precipitate calcium carbonate in its environment by the decomposition of urea into ammonium and carbonate. The bacterial degradation of urea basically increases the pH and promotes the microbial deposition of carbonate as calcium carbonate. In this research, the capability of bacteria to influence the formation of HCO3- by the production of urease enzyme was investigated. Results of growth rate and characteristics of bacteria showed that 20g/L of urea concentration was able to provide a good environment for bacteria with sufficient amount of nutrient to survive. The formation of HCO3- was parallel with NH3 production where the formation of HCO3- increased slowly as the ammonia production decreased. Urea degradation with suitable concentration of urea by 20g/L may form high HCO3- compared to 25g/L urea concentration. The results from the experimental works indicated that the optimal urea concentration was 20g/L.

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7

Errington, Jeff. "Cell wall-deficient, L-form bacteria in the 21st century: a personal perspective". Biochemical Society Transactions 45, n.º 2 (13 de abril de 2017): 287–95. http://dx.doi.org/10.1042/bst20160435.

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The peptidoglycan (PG) cell wall is a defining feature of the bacteria. It emerged very early in evolution and must have contributed significantly to the success of these organisms. The wall features prominently in our thinking about bacterial cell function, and its synthesis involves the action of several dozen proteins that are normally essential for viability. Surprisingly, it turns out to be relatively simple to generate bacterial genetic variants called L-forms that completely lack PG. They grow robustly provided that lack of the cell wall is compensated for by an osmoprotective growth medium. Although their existence has been noted and studied on and off for many decades, it is only recently that modern molecular and cellular methods have been applied to L-forms. We used Bacillus subtilis as an experimental model to understand the molecular basis for the L-form switch. Key findings included the discovery that L-forms use an unusual blebbing, or tubulation and scission mechanism to proliferate. This mechanism is completely independent of the normal FtsZ-based division machinery and seems to require only an increased rate of membrane synthesis, leading to an increased surface area-to-volume ratio. Antibiotics that block cell wall precursor synthesis, such as phosphomycin, efficiently induce the L-form switch without the need for genetic change. The same antibiotics turned out to induce a similar L-form switch in a wide range of bacteria, including Escherichia coli, in which we showed that proliferation was again FtsZ-independent. Aside from further basic science, future work on L-forms is likely to focus on their possible role in chronic or recurrent infections, their use as a model in studies of the origins of life, and possibly, biotechnological applications.

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Ibrahim, Arsyik, Aditya Fridayanti y Fila Delvia. "ISOLASI DAN IDENTIFIKASI BAKTERI ASAM LAKTAT (BAL) DARI BUAH MANGGA (Mangifera indica L.)". Jurnal Ilmiah Manuntung 1, n.º 2 (26 de enero de 2017): 159. http://dx.doi.org/10.51352/jim.v1i2.29.

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The research has been done for the isolation and identification of lactic acid bacteria (LAB) from mango (Mangifera indica L.). This research aimed to isolated of lactic acid bacteria that is in mango (Mangifera indica L.) and determine the characteristics of lactic acid bacteria isolate (LAB) of mango (Mangifera indica L.). The method used is spoiled technique of mango (Mangifera indica L.) and isolation using selective media MRS Broth and MRS Agar. The identification isolate of lactic acid bacteria (LAB) used methods macroscopically and microscopically with indirect coloring, gram staining and used biochemical with katalase testing. The results obtained in the form of characteristic isolate of lactic acid bacteria displayed form of bacteria with circle, smooth surface, curve, entire side and white. The microscopically displayed stick form of bacteria and purple with gram coloring

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Xu, Yuanyuan, Baoping Zhang, Li Wang, Tao Jing, Jing Chen, Xiaogang Xu, Wenhong Zhang, Ying Zhang y Jian Han. "Unusual features and molecular pathways of Staphylococcus aureus L-form bacteria". Microbial Pathogenesis 140 (marzo de 2020): 103970. http://dx.doi.org/10.1016/j.micpath.2020.103970.

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Innes, C. M. J. y E. J. Allan. "Induction, growth and antibiotic production of Streptomyces viridifaciens L-form bacteria". Journal of Applied Microbiology 90, n.º 3 (2 de marzo de 2001): 301–8. http://dx.doi.org/10.1046/j.1365-2672.2001.01243.x.

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Kobierzyńska-Gołąb, Z. "Wpływ szczepów bakterii wyizolowanych z hydroponicznej uprawy sałaty (Lactuca sativa L.) na wzrost siewek sałaty, rosnących w obecnosci rożnych form pożywienia azotowego [Influence of bacterial strains isolated from hydroponic cultures of lettuce (Lactuca sativa L.) on the growth of lettuce seedlings growing in the presence of various forms of nitrogen nutrition]". Acta Agrobotanica 32, n.º 2 (2015): 195–206. http://dx.doi.org/10.5586/aa.1979.018.

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320 bacterial strains isolated from the surface of cultivated plants, as well as from other parts of hydroponic cultures showed stimulating (49 bacterial strains) or inhibitory (9 bacterial strains) properties in respect to the investigated plant. The following bacteria were isolated: Pseudomonas, Flavobacterium, Agrobacterium, Achromobacter and Chromobacterium. The effects of active bacterial strains on the growth of seedlings were investigated in dependence on the kind of inorganic form of nitrogen present in the nutrient solutions. The same bacterial strains exerted a stimulating effect on seedlings growing on nitrates, weaker stimulation was observed in cultures with ammonium nitrate; the growth of lettuce seedlings on nutrient solution with ammonium only, was, as a rule, inhibited by the bacteria.

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Briers, Yves, Titu Staubli, Markus C. Schmid, Michael Wagner, Markus Schuppler y Martin J. Loessner. "Intracellular Vesicles as Reproduction Elements in Cell Wall-Deficient L-Form Bacteria". PLoS ONE 7, n.º 6 (6 de junio de 2012): e38514. http://dx.doi.org/10.1371/journal.pone.0038514.

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Fuji Arriani, Intan, Abdul Latief Abadi y Luqman Qurata Aini. "KARAKTERISASI BAKTERI PATOGEN PENYEBAB LAYU PADA TANAMAN BAWANG MERAH (Allium ascalonicum L.)". VIABEL: Jurnal Ilmiah Ilmu-Ilmu Pertanian 14, n.º 1 (30 de mayo de 2020): 69–75. http://dx.doi.org/10.35457/viabel.v14i1.1004.

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Shallot (Allium ascalonicum L.) is one of the vegetable commodities in the form of tubers that have a high economic value. The development of shallot cultivation in Indonesia often experiences obstacles, one of which is an obstacle in the process of shallot cultivation, namely the attack of Plant Disturbing Organisms (OPT). Information about diseases caused by pathogenic bacteria is still very limited. This study aims to determine the symptoms and identification of pathogenic bacteria that cause wilt in shallots. Bacterial isolation was carried out using Nutrient Agar (NA) media and 36 bacterial isolates were collected from shallots. Bacterial isolates were then tested for pathogenicity to determine the ability of bacteria to cause wilt disease in shallots. The results of isolation obtained 10 bacterial isolates that can show symptoms on red onions namely wilted leaves, yellow and soft rotten tubers. Four isolates including positive can show hypersensitivity symptoms, namely M11, N20, N17 and N14. Based on the identification of bacteria in physiology showed 2 groups of different isolates. Biochemical test results of Isolate M11, N20 and show species suspected of B. cepacia. N3 and N14 isolates are suspected to be E. carotavora subsp. carotavora. The bacterial isolates N7, N17, P5 and P7 were suspected to be E. carotavora subsp. betavasculorum. The isolate of N4 bacteria is suspected to be E. cacticida.

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Kilcher, Samuel, Patrick Studer, Christina Muessner, Jochen Klumpp y Martin J. Loessner. "Cross-genus rebooting of custom-made, synthetic bacteriophage genomes in L-form bacteria". Proceedings of the National Academy of Sciences 115, n.º 3 (3 de enero de 2018): 567–72. http://dx.doi.org/10.1073/pnas.1714658115.

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Engineered bacteriophages provide powerful tools for biotechnology, diagnostics, pathogen control, and therapy. However, current techniques for phage editing are experimentally challenging and limited to few phages and host organisms. Viruses that target Gram-positive bacteria are particularly difficult to modify. Here, we present a platform technology that enables rapid, accurate, and selection-free construction of synthetic, tailor-made phages that infect Gram-positive bacteria. To this end, custom-designed, synthetic phage genomes were assembled in vitro from smaller DNA fragments. We show that replicating, cell wall-deficientListeria monocytogenesL-form bacteria can reboot synthetic phage genomes upon transfection, i.e., produce virus particles from naked, synthetic DNA. Surprisingly,ListeriaL-form cells not only support rebooting of native and syntheticListeriaphage genomes but also enable cross-genus reactivation ofBacillusandStaphylococcusphages from their DNA, thereby broadening the approach to phages that infect other important Gram-positive pathogens. We then used this platform to generate virulent phages by targeted modification of temperate phage genomes and demonstrated their superior killing efficacy. These synthetic, virulent phages were further armed by incorporation of enzybiotics into their genomes as a genetic payload, which allowed targeting of phage-resistant bystander cells. In conclusion, this straightforward and robust synthetic biology approach redefines the possibilities for the development of improved and completely new phage applications, including phage therapy.

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15

da Silva Tatley, Fernanda, Frank E. Aldwell, Anita K. Dunbier y Parry J. Guilford. "N-Terminal E-Cadherin Peptides Act as Decoy Receptors for Listeria monocytogenes". Infection and Immunity 71, n.º 3 (marzo de 2003): 1580–83. http://dx.doi.org/10.1128/iai.71.3.1580-1583.2003.

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ABSTRACT The observation that E-cadherin is the principal epithelial receptor for the bacterial pathogen Listeria monocytogenes led us to investigate whether N-terminal fragments of E-cadherin containing the L. monocytogenes binding domain could inhibit entry of the bacteria into cultured epithelial cells. Here we demonstrate that a conditioned medium from a gastric cancer cell line (Kato III) that carries a truncating CDH-1 mutation 3′ of the L. monocytogenes binding domain can inhibit the uptake of the bacteria into Caco-2 cells. The inhibitory activity of the Kato III conditioned medium could be mimicked by incubation of the bacteria with a recombinant 26-kDa N-terminal E-cadherin peptide prior to infection. Furthermore, these data suggest that cleavage of the 80-kDa extracellular domain of E-cadherin from the cell surface may provide an innate form of pathogen defense by acting as a decoy receptor for L. monocytogenes.

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Polito, Flavio, Giuseppe Amato, Lucia Caputo, Vincenzo De Feo, Florinda Fratianni, Vincenzo Candido y Filomena Nazzaro. "Chemical Composition and Agronomic Traits of Allium sativum and Allium ampeloprasum Leaves and Bulbs and Their Action against Listeria monocytogenes and Other Food Pathogens". Foods 11, n.º 7 (29 de marzo de 2022): 995. http://dx.doi.org/10.3390/foods11070995.

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In this work, we aimed to study the chemical composition of the essential oils from bulbs and leaves of two cultivars of Allium sativum L. and two of A. ampeloprasum L. var. holmense. Moreover, we investigated their activity against four common bacterial strains responsible for food contamination (Listeria monocytogenes, Escherichia coli, Acinetobacter baumannii, and Staphylococcus aureus) by formation of biofilms. The susceptibility of bacterial biofilms was evaluated by crystal violet assay, whereas the metabolic changes occurring in the bacterial cells were ascertained through the MTT test. The essential oils were characterized by the presence of most characteristic components, although with different composition between the species and the cultivars. The essential oils inhibited the capacity of the pathogenic bacteria to form biofilms (up to 79.85 against L. monocytogenes) and/or acted on their cell metabolism (with inhibition of 68.57% and 68.89% against L. monocytogenes and S. aureus, respectively). The capacity of the essential oils to act against these foodborne bacteria could suggests further ideas for industrial applications and confirms the versatility of these essential oils as food preservatives.

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17

Daulagala, P. "Induction of Resistance in Poplar to Melampsora larici-populina Using L-form Bacteria". Asian Journal of Biology 6, n.º 3 (26 de junio de 2018): 1–9. http://dx.doi.org/10.9734/ajob/2018/41044.

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18

Waterhouse, Rosemary N., Eunice J. Allan, Firoz Amijee, Valerie J. Undrill y L. Anne Glover. "An investigation of enumeration and DNA partitioning in Bacillus subtilis L-form bacteria". Journal of Applied Bacteriology 77, n.º 5 (noviembre de 1994): 497–503. http://dx.doi.org/10.1111/j.1365-2672.1994.tb04393.x.

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19

Kawai, Yoshikazu, Romain Mercier, Ling Juan Wu, Patricia Domínguez-Cuevas, Taku Oshima y Jeff Errington. "Cell Growth of Wall-Free L-Form Bacteria Is Limited by Oxidative Damage". Current Biology 25, n.º 12 (junio de 2015): 1613–18. http://dx.doi.org/10.1016/j.cub.2015.04.031.

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Kawai, Yoshikazu, Katarzyna Mickiewicz y Jeff Errington. "Lysozyme Counteracts β-Lactam Antibiotics by Promoting the Emergence of L-Form Bacteria". Cell 172, n.º 5 (febrero de 2018): 1038–49. http://dx.doi.org/10.1016/j.cell.2018.01.021.

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Allan, E. J., J. Jass, L. E. Phillips, J. W. Costerton y H. M. Lappin-Scott. "A novel method for differentiating L-form bacteria from their parental form using the Hucker Gram staining technique". Letters in Applied Microbiology 15, n.º 5 (noviembre de 1992): 193–96. http://dx.doi.org/10.1111/j.1472-765x.1992.tb00761.x.

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Yuanting, Li, Cheng Cong y An Dengdi. "Characterisation of endophytic bacteria from a desert plant Lepidium perfoliatum L." Plant Protection Science 53, No. 1 (5 de enero de 2017): 32–43. http://dx.doi.org/10.17221/14/2016-pps.

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Sixty-two endophytic bacteria from the leaves, roots, and stems of healthy Lepidium perfoliatum L. were isolated and characterised. From the results, 89, 87, 90, and 97% isolates could tolerate 12% NaCl, 30% PEG 6000, 50°C and pH 10, respectively. 74% isolates could form a biofilm. Besides, 28 isolates could improve the germination rate of host seeds under different degree of drought stress. These data suggest that the endophyte isolates show considerable resistance to abiotic stress and assist their plant hosts to germinate under drought stress.

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Mampel, Jörg, Thomas Spirig, Stefan S. Weber, Janus A. J. Haagensen, Søren Molin y Hubert Hilbi. "Planktonic Replication Is Essential for Biofilm Formation by Legionella pneumophila in a Complex Medium under Static and Dynamic Flow Conditions". Applied and Environmental Microbiology 72, n.º 4 (abril de 2006): 2885–95. http://dx.doi.org/10.1128/aem.72.4.2885-2895.2006.

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ABSTRACT Legionella pneumophila persists for a long time in aquatic habitats, where the bacteria associate with biofilms and replicate within protozoan predators. While L. pneumophila serves as a paradigm for intracellular growth within protozoa, it is less clear whether the bacteria form or replicate within biofilms in the absence of protozoa. In this study, we analyzed surface adherence of and biofilm formation by L. pneumophila in a rich medium that supported axenic replication. Biofilm formation by the virulent L. pneumophila strain JR32 and by clinical and environmental isolates was analyzed by confocal microscopy and crystal violet staining. Strain JR32 formed biofilms on glass surfaces and upright polystyrene wells, as well as on pins of “inverse” microtiter plates, indicating that biofilm formation was not simply due to sedimentation of the bacteria. Biofilm formation by an L. pneumophila fliA mutant lacking the alternative sigma factor σ28 was reduced, which demonstrated that bacterial factors are required. Accumulation of biomass coincided with an increase in the optical density at 600 nm and ceased when the bacteria reached the stationary growth phase. L. pneumophila neither grew nor formed biofilms in the inverse system if the medium was exchanged twice a day. However, after addition of Acanthamoeba castellanii, the bacteria proliferated and adhered to surfaces. Sessile (surface-attached) and planktonic (free-swimming) L. pneumophila expressed β-galactosidase activity to similar extents, and therefore, the observed lack of proliferation of surface-attached bacteria was not due to impaired protein synthesis or metabolic activity. Cocultivation of green fluorescent protein (GFP)- and DsRed-labeled L. pneumophila led to randomly interspersed cells on the substratum and in aggregates, and no sizeable patches of clonally growing bacteria were observed. Our findings indicate that biofilm formation by L. pneumophila in a rich medium is due to growth of planktonic bacteria rather than to growth of sessile bacteria. In agreement with this conclusion, GFP-labeled L. pneumophila initially adhered in a continuous-flow chamber system but detached over time; the detachment correlated with the flow rate, and there was no accumulation of biomass. Under these conditions, L. pneumophila persisted in biofilms formed by Empedobacter breve or Microbacterium sp. but not in biofilms formed by Klebsiella pneumoniae or other environmental bacteria, suggesting that specific interactions between the bacteria modulate adherence.

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Riyadi, Farid Mukhtar, Arief Prajitno, Mohamad Fadjar, Arif Syaifurrisal y Annisa Isti Fauziyyah. "Potential of Moringa (Moringa oleifera) leaf extract to inhibit the growth of pathogenic bacteria Edwardsiella tarda". Journal of Aquaculture and Fish Health 10, n.º 3 (31 de agosto de 2021): 321. http://dx.doi.org/10.20473/jafh.v10i3.25057.

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This study analyzed the antibacterial activity of Moringa oliefera leaf extract against the growth of Edwardsiella tarda bacteria. This study aims to determine the antibacterial activity of Moringa leaf extract (M. oliefera) against the growth of E.tarda bacteria. Inhibition testing is done by diffusion method (disc test). The disc test used five variations of concentration of 75 mg/L, 150 mg/L, 225 mg/L, 300 mg/L, and 375 mg/L on TSA (Tryptone Soya Agar) media and incubated for 2x24 hours. As a positive control, an antibiotic in the form of chloramphenicol was used. (5 mg/L) Moreover, distilled water was used as a negative control.Moringa leaf extract (M. oliefera) contains natural active compounds, bacteriostatic antibacterials, due to decreased bacterial growth after 48 hours of incubation. The highest inhibition diameter of E. tarda was 12.95 mm at a concentration of 375 mg/L after 24 hours incubation and decreased by 11.02 mm after 48 hours incubation. The highest inhibitory effectiveness was at a concentration of 375 mg/L with an effectiveness of 58.8%, while the effectiveness of the decrease was 48.1% after 48 hours of incubation.

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Antolak, Hubert, Agata Czyżowska y Dorota Kręgiel. "Activity of Mentha piperita L. Ethanol Extract against Acetic Acid Bacteria Asaia spp." Foods 7, n.º 10 (18 de octubre de 2018): 171. http://dx.doi.org/10.3390/foods7100171.

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Acetic acid bacteria belonging to the genus Asaia spp. are relatively new microbial contaminants in the beverage industry. These bacteria cause organoleptic changes such as increased turbidity, haziness and sour odor. In addition, they are able to form biofilms on the inner parts of production lines, and finally they can cause secondary contamination of final products. For this reason, new methods using effective and safe preservatives are being developed to improve microbial stability of soft beverages. The aim of the research was to investigate the effects of Mentha piperita L. ethanol extract against Asaia spp. biofilm formation. The bacterial adhesion was evaluated by a plate count method and luminometry, as well as fluorescence microscopy. The polyphenolic profile of the mint extract was determined on the basis of high-performance liquid chromatography (HPLC). The obtained microbiological results indicate bacteriostatic effect of mint extract at 10% (v/v) concentration. The plant extract also reduces the number of adhered bacterial cells on polystyrene surface.

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Kim, Sam Woong, Yeon Jo Ha, Kyu Ho Bang, Seungki Lee, Joo-Hong Yeo, Hee-Sun Yang, Tae-Won Kim, Kyu Pil Lee y Woo Young Bang. "Potential of Bacteriocins from Lactobacillus taiwanensis for Producing Bacterial Ghosts as a Next Generation Vaccine". Toxins 12, n.º 7 (1 de julio de 2020): 432. http://dx.doi.org/10.3390/toxins12070432.

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Bacteriocins are functionally diverse toxins produced by most microbes and are potent antimicrobial peptides (AMPs) for bacterial ghosts as next generation vaccines. Here, we first report that the AMPs secreted from Lactobacillus taiwanensis effectively form ghosts of pathogenic bacteria and are identified as diverse bacteriocins, including novel ones. In detail, a cell-free supernatant from L. taiwanensis exhibited antimicrobial activities against pathogenic bacteria and was observed to effectively cause cellular lysis through pore formation in the bacterial membrane using scanning electron microscopy (SEM). The treatment of the cell-free supernatant with proteinase K or EDTA proved that the antimicrobial activity is mediated by AMPs, and the purification of AMPs using Sep-Pak columns indicated that the cell-free supernatant includes various amphipathic peptides responsible for the antimicrobial activity. Furthermore, the whole-genome sequencing of L. taiwanensis revealed that the strain has diverse bacteriocins, confirmed experimentally to function as AMPs, and among them are three novel bacteriocins, designated as Tan 1, Tan 2, and Tan 3. We also confirmed, using SEM, that Tan 2 effectively produces bacterial ghosts. Therefore, our data suggest that the bacteriocins from L. taiwanensis are potentially useful as a critical component for the preparation of bacterial ghosts.

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Casasola-Rodríguez, B., M. T. Orta de Velásquez, V. G. Luqueño-Martínez y I. Monje-Ramírez. "Quantification of Helicobacter pylori in the viable but nonculturable state by quantitative PCR in water disinfected with ozone". Water Science and Technology 68, n.º 11 (22 de octubre de 2013): 2468–72. http://dx.doi.org/10.2166/wst.2013.512.

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Helicobacter pylori is a Gram-negative spiral-shaped bacterium that colonizes the gastric mucosa and is associated with gastric diseases. It may present a morphological adaptation when it is out of its natural environment, such as in water. The morphological adaptation is a coccoid form, which is a viable but non-culturable state (VNC) in which the DNA remains active and therefore infective. Due to the impossibility of culture by traditional methods in the VNC state, we developed a methodology that includes a molecular technique, quantitative polymerase chain reaction (qPCR), which is capable of measuring the bacteria in both forms (helical and coccoidal) and therefore is able to measure a disinfection process and to estimate the resistance of the bacteria to ozone. The methodology developed measures the efficiency of the ozone disinfection when bacteria are in a VNC state only. Bacterial culture at 9 × 108CFU/mL diluted in 40 mL reaction volumes were exposed to a wide range of CT values (0.11–15 mg min/L). The results show a 3.92-log reduction when treated with 15 mg min/L. Our results demonstrate the feasibility of using qPCR for the quantification and detection of H. pylori, in coccoid form, in water systems treated with an ozone disinfection process.

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Robbins, Jennifer R., Angela I. Barth, Hélène Marquis, Eugenio L. de Hostos, W. James Nelson y Julie A. Theriot. "Listeria monocytogenes Exploits Normal Host Cell Processes to Spread from Cell to Cell✪". Journal of Cell Biology 146, n.º 6 (20 de septiembre de 1999): 1333–50. http://dx.doi.org/10.1083/jcb.146.6.1333.

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The bacterial pathogen, Listeria monocytogenes, grows in the cytoplasm of host cells and spreads intercellularly using a form of actin-based motility mediated by the bacterial protein ActA. Tightly adherent monolayers of MDCK cells that constitutively express GFP-actin were infected with L. monocytogenes, and intercellular spread of bacteria was observed by video microscopy. The probability of formation of membrane-bound protrusions containing bacteria decreased with host cell monolayer age and the establishment of extensive cell-cell contacts. After their extension into a recipient cell, intercellular membrane-bound protrusions underwent a period of bacterium-dependent fitful movement, followed by their collapse into a vacuole and rapid vacuolar lysis. Actin filaments in protrusions exhibited decreased turnover rates compared with bacterially associated cytoplasmic actin comet tails. Recovery of motility in the recipient cell required 1–2 bacterial generations. This delay may be explained by acid-dependent cleavage of ActA by the bacterial metalloprotease, Mpl. Importantly, we have observed that low levels of endocytosis of neighboring MDCK cell surface fragments occurs in the absence of bacteria, implying that intercellular spread of bacteria may exploit an endogenous process of paracytophagy.

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Alonzo, Francis, Gary C. Port, Min Cao y Nancy E. Freitag. "The Posttranslocation Chaperone PrsA2 Contributes to Multiple Facets of Listeria monocytogenes Pathogenesis". Infection and Immunity 77, n.º 7 (18 de mayo de 2009): 2612–23. http://dx.doi.org/10.1128/iai.00280-09.

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ABSTRACT Listeria monocytogenes is an intracellular bacterial pathogen whose virulence depends on the regulated expression of numerous secreted bacterial factors. As for other gram-positive bacteria, many proteins secreted by L. monocytogenes are translocated across the bacterial membrane in an unfolded state to the compartment existing between the membrane and the cell wall. This compartment presents a challenging environment for protein folding due to its high density of negative charge, high concentrations of cations, and low pH. We recently identified PrsA2 as a gene product required for L. monocytogenes virulence. PrsA2 was identified based on its increased secretion by strains containing a mutationally activated form of prfA, the key regulator of L. monocytogenes virulence gene expression. The prsA2 gene product is one of at least two predicted peptidyl-prolyl cis/trans-isomerases encoded by L. monocytogenes; these proteins function as posttranslocation protein chaperones and/or foldases. In this study, we demonstrate that PrsA2 plays a unique and important role in L. monocytogenes pathogenesis by promoting the activity and stability of at least two critical secreted virulence factors: listeriolysin O (LLO) and a broad-specificity phospholipase. Loss of PrsA2 activity severely attenuated virulence in mice and impaired bacterial cell-to-cell spread in host cells. In contrast, mutants lacking prsA1 resembled wild-type bacteria with respect to intracellular growth and cell-to-cell spread as well as virulence in mice. PrsA2 is thus distinct from PrsA1 in its unique requirement for the stability and full activity of L. monocytogenes-secreted factors that contribute to host infection.

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Peters, Marjolein C. F. M., Maarten G. A. Keuten, Aleksandra Knezev, Mark C. M. van Loosdrecht, Johannes S. Vrouwenvelder, Luuk C. Rietveld y Merle K. de Kreuk. "Characterization of the bacterial community in shower water before and after chlorination". Journal of Water and Health 16, n.º 2 (21 de diciembre de 2017): 233–43. http://dx.doi.org/10.2166/wh.2017.189.

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Abstract Bathers release bacteria in swimming pool water, but little is known about the fate of these bacteria and potential risks they might cause. Therefore, shower water was characterized and subjected to chlorination to identify the more chlorine-resistant bacteria that might survive in a chlorinated swimming pool and therefore could form a potential health risk. The total community before and after chlorination (1 mg Cl2 L−1 for 30 s) was characterized. More than 99% of the bacteria in the shower water were Gram-negative. The dominant bacterial families with a relative abundance of ≥10% of the total (non-chlorinated and chlorinated) communities were Flavobacteriaceae (24–21%), Xanthomonadaceae (23–24%), Moraxellaceae (12–11%) and Pseudomonadaceae (10–22%). The relative abundance of Pseudomonadaceae increased after chlorination and increased even more with longer contact times at 1 mg Cl2L−1. Therefore, Pseudomonadaceae were suggested to be relatively more chlorine resistant than the other identified bacteria. To determine which bacteria could survive chlorination causing a potential health risk, the relative abundance of the intact cell community was characterized before and after chlorination. The dominant bacterial families in the intact community (non-chlorinated and chlorinated) were Xanthomonadaceae (21–17%) and Moraxellaceae (48–57%). Moraxellaceae were therefore more chlorine resistant than the other identified intact bacteria present.

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31

Trousil, Jiří, Lucia Frgelecová, Pavla Kubíčková, Kristína Řeháková, Vladimír Drašar, Jana Matějková, Petr Štěpánek y Oto Pavliš. "Acute Pneumonia Caused by Clinically Isolated Legionella pneumophila Sg 1, ST 62: Host Responses and Pathologies in Mice". Microorganisms 10, n.º 1 (14 de enero de 2022): 179. http://dx.doi.org/10.3390/microorganisms10010179.

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Legionnaires’ disease is a severe form of lung infection caused by bacteria belonging to the genus Legionella. The disease severity depends on both host immunity and L. pneumophila virulence. The objective of this study was to describe the pathological spectrum of acute pneumonia caused by a virulent clinical isolate of L. pneumophila serogroup 1, sequence type 62. In A/JOlaHsd mice, we compared two infectious doses, namely, 104 and 106 CFU, and their impact on the mouse status, bacterial clearance, lung pathology, and blood count parameters was studied. Acute pneumonia resembling Legionnaires’ disease has been described in detail.

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32

Zhang, Xin Yu, Ying Fu, Li Ping Qiu y Yan Zhen Yu. "Study on Water Distribution System's Biological Stability of Northern Living District". Applied Mechanics and Materials 361-363 (agosto de 2013): 574–77. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.574.

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AOC and BDOC are used to estimate the biostability of water distribution system in a northern living district of China. The results show that the concentrations of AOC and BDOC are 57.6 to 369.3 μg/L and 0.81 to 2.43 mg/L in water which is biologically unstable. The concentration of BDOC generally reduced with the along monitoring sites. The concentration of BDOC is greatly influence by residual chlorine and bacteria activity in water distribution system. The concentration of AOC is between 57.6 μg/L and 369.3 μg/L, and the bacteria number is form 5 to 43.

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33

Chasanah, Ekowati, Usman Sumo Friend Tambunan y Tanti Yulianti. "SCREENING AND CHARACTERIZATION OF L-GLUTAMINASE PRODUCED BY BACTERIA ISOLATED FROM SANGIHE TALAUD SEA". Squalen Bulletin of Marine and Fisheries Postharvest and Biotechnology 7, n.º 3 (8 de mayo de 2013): 115. http://dx.doi.org/10.15578/squalen.v7i3.6.

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L-glutaminase (L-glutamine amidohydrolase, EC 3.5.1.2) is a very important enzyme due to its role as flavor enhancer and antileukemic agent. Salt-tolerant L-glutaminase produced bymarine bacteria is favorable in food industries. This study describes the screening of L- glutaminase producing marine bacteria from Sangihe-Talaud Sea, North Sulawesi, Indonesia.Screening of L-glutaminase was performed using a liquid medium and identification of selected isolate was performed using molecular-based 16S rDNA. Results showed that there were 7 isolates produced positive results of L-glutaminase, and one of them (II.1 isolate) produced the highest activity, i.e 147.99 U/L, equivalent to the specific activity of 62.32 U/mg. The isolate then selected for further study. Bacterial identification based on 16S rRNA sequencing has revealed that the isolate was 96% similar to Pseudomonas aeruginosa strain CG-T8. Characterization of extracellular L-glutaminase from the II.1 isolate showed that the enzyme worked optimally at temperature of 37-45 °C and pH 7. The enzyme was stable when NaCl solution was added up to 8% and began to decrease on addition of NaCl solution of 16% and 20% with relative activity of 79% and 74%, respectively. The effect of metal ions, e.g Mn2+, Mg2+, and Co2+ in the form of chloride salt, were able to increase enzyme activity, whereas the addition of other metal ions (Zn2+, Fe3+, and Ca2+) decreased the activity. The molecular weights of L-glutaminase was estimated around42 kDa and 145 kDa.

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34

Nakamura, K., M. Shibata y Y. Miyaji. "Substrate Affinity of Oligotrophic Bacteria in Biofilm Reactors". Water Science and Technology 21, n.º 8-9 (1 de agosto de 1989): 779–90. http://dx.doi.org/10.2166/wst.1989.0281.

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Several biofilm reactors were operated to investigate the substrate affinity of oligotrophic bacteria in the biofilm reactor. The attached oligotrophs were removed from reactors, and substrate affinity was determined in dispersed form. The saturation constant (Ks) of attached oligotrophs for acetate was less than 10 µg-C/l. The apparent Ks (Ksa) values of reactors were also determined to evaluate the performance of reactors,and the effect of specific surface area of packed media on Ksa was investigated at a loading of 0.006 mg-C per cm3-apparent media volume per hour. Larger specific surface area led to smaller Ksa, and 6.9 µg-C/l of Ksa for acetate was obtained with the media having 340 cm2 -surface area per cm -apparent media volume of specific surface area. The bacterial flora in the oligotrophic biofilm was examined, and Pseudomonas was found to be dominant.

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35

Mayo, A. W. y T. Noike. "Response of mixed cultures of chlorella vulgaris and heterotrophic bacteria to variation of pH". Water Science and Technology 30, n.º 8 (1 de octubre de 1994): 285–94. http://dx.doi.org/10.2166/wst.1994.0426.

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The effects of hydrogen ion concentration on the growth of heterotrophic bacteria and alga Chlorella vulgaris, one of the dominant species in waste stabilization ponds were investigated in fed batch cultures. Glucose used as a source of organic carbon was fed daily in granular form and pH was controlled between 3.0 and 11.5 by addition of either HCl or NaOH. Heterotrophic bacterial densities were highest between pH 4.0 and 5.5, but the growth rate of Chlorella vulgaris was optimum at pH 4.5∼8.0. Chlorella vulgaris was sensitive to alkaline pH values, with maximum growth rates, μmax, of 2.03, 1.12 and 0.75 d−1 at pH 7.0, 9.0 and 10.0, respectively. The saturation constants, Ks, for the same pH values were 181, 157 and 52 mg/l, respectively. The optimum total biomass yield was 0.381 mg POC/mg glucose and was observed at pH 5.5∼8.0, but the magnitude was strongly influenced by the pre-culture pH conditions. Glucose metabolism was significantly affected at alkaline conditions than at acidic conditions. These results also suggest that in a mixed culture with bacteria, algae are largely responsible for glucose metabolism, with apparent saturation constants at pH 7.0 of 27 mg/l and 181 mg/l for bacteria and Chlorella vulgaris, respectively.

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36

Eremia, Mihaela Carmen, Irina Lupescu, Mariana Vladu, Maria Petrescu, Gabriela Savoiu, Amalia Stefaniu y Maria Spiridon. "Studies on poly-3-hydroxyoctanoate biosynthesis by a consortium of microorganisms". Ovidius University Annals of Chemistry 27, n.º 1 (1 de junio de 2016): 44–47. http://dx.doi.org/10.1515/auoc-2016-0009.

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Abstract Polyhydroxyalcanoates (PHAs) are specifically produced by a wide variety of bacteria, as an intracellular energy reserve in the form of homo- and copolymers of [R]-β-hydroxyalkanoic acids, depending on the C source used for microorganism growth, when the cells are grown under stressing conditions. In this paper we present microbiological accumulation of poly-3-hydroxyoctanoate (PHO) by using a consortium of bacterial strains, Pseudomonas putida and Bacillus subtilis, in a rate of 3:1, grown on a fermentation medium based on sodium octanoate as the sole carbon source. The experiments performed in the above mentioned conditions led to the following results: from 18.70 g sodium octanoate (7.72 g/L in the fermentation medium) used up during the bioprocess, 3.93-3.96 g/L dry bacterial biomass and 1.834 - 1.884 g/L PHA, containing 85.83 - 86.8% PHO, were obtained.

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37

Tanuwidjaja, Irina y Mirna Mrkonjic Fuka. "Ozone in Droplets and Mist in Inhibition of Phytopathogenic Microbiota". Agriculture 12, n.º 11 (9 de noviembre de 2022): 1875. http://dx.doi.org/10.3390/agriculture12111875.

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Ozon is considered an environmentally friendly, low-cost antimicrobial treatment and an effective alternative to chemical pesticides. Ozonated water in the form of droplets and mist has been used in two concentrations (4 and 2 mg/L) against three biomasses (102, 104, and 106 CFU/mL) of phytopathogenic bacteria Erwinia amylovora, Pseudomonas syringae, and Agrobacterium tumefaciens and fungus Botrytis cinerea that infest a wide range of crops worldwide and pose a threat to global food production. Regardless of concentration, ozone dissolved in water showed a pronounced inhibitory effect on phytopathogenic bacteria when applied in the form of droplets. However, the effect was only detected when the bacterial load was not higher than 104 CFU/mL, indicating the necessity to treat the crops and plant materials when the bacterial load is still manageable. Unlike bacterial phytopathogens, B. cinerea was the most susceptible to treatment with aqueous ozone, regardless of the applied biomass, ozone concentration, or type of application. Total removal of high biomass of B. cinerea was achieved even with the lowest ozonated water concentration thus underlying the power of ozone in treating this particular fungal contamination.

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38

Sharma, Tanu y Sidhu MC. "Evaluation of antibacterial activity of selected plant species from the State of Punjab, India". International Journal of Ayurvedic Medicine 13, n.º 2 (8 de julio de 2022): 520–26. http://dx.doi.org/10.47552/ijam.v13i2.2619.

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Objective: Evaluation of antibacterial potential of aqueous and ethanol extracts of Solanum nigrum L., Eclipta alba (L.) Hassk., Achyranthes aspera L., Sida acuta Burm.f., Justicia adhatoda L. (Syn. Adhatoda vasica Nees), Boerhavia diffusa L. and Withania somnifera (L.) Dunal against human pathogenic bacteria Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Materials and Methods: Powdered form of the whole plant of each species was extracted in aqueous and ethanol solvents. The antibacterial activity experiment was performed using agar well diffusion method. A dose of 50µl, 100µl and 150µl of each extract (aqueous and ethanol) were tested. Results: Only the ethanol extracts have shown activity against test organisms. The 50µl and 100µl doses of extracts were not much effective against all the bacteria. Thus 150µl volume was selected for further study. The ethanol extract of Adhatoda vasica has yielded maximum zone of inhibition 24±1.7mm and 22±2.1mm against S. aureus and E. coli, respectively. Type AA3 of A. aspera and SN3 of S. nigrum were the most effective against E. faecalis with inhibition zones 22±2.2mm and 21±2.2mm, respectively. Similarly, B. diffusa has shown maximum inhibition against P. aeruginosa. Conclusion: The present study suggests the use of ethanol extract since none of the aqueous extracts have shown activity against all the tested bacteria. The difference in activity of different plant extracts may be due to variable chemical composition of the plant species. The plant species can be selected based on the bacterial species to be investigated. Further studies can be planned to understand the bioactive molecules responsible for antibacterial activity.

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BAUTISTA, DERRICK A., RONALD B. PEGG y PHYLLIS J. SHAND. "Effect of l-Glucose and d-Tagatose on Bacterial Growth in Media and a Cooked Cured Ham Product". Journal of Food Protection 63, n.º 1 (1 de enero de 2000): 71–77. http://dx.doi.org/10.4315/0362-028x-63.1.71.

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Cured meats such as ham can undergo premature spoilage on account of the proliferation of lactic acid bacteria. This spoilage is generally evident from a milkiness in the purge of vacuum-packaged sliced ham. Although cured, most hams are at more risk of spoilage than other types of processed meat products because they contain considerably higher concentrations of carbohydrates, ∼2 to 7%, usually in the form of dextrose and corn syrup solids. Unfortunately, the meat industry is restricted with respect to the choice of preservatives and bactericidal agents. An alternative approach from these chemical compounds would be to use novel carbohydrate sources that are unrecognizable to spoilage bacteria. l-Glucose and d-tagatose are two such potential sugars, and in a series of tests in vitro, the ability of bacteria to utilize each as an energy source was compared to that of d-glucose. Results showed that both l-glucose and d-tagatose are not easily catabolized by a variety of lactic bacteria and not at all by pathogenic bacteria such as Escherichia coli O157:H7, Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus, and Yersinia enterocolitica. In a separate study, d-glucose, l-glucose, and d-tagatose were added to a chopped and formed ham formulation and the rate of bacterial growth was monitored. Analysis of data by a general linear model revealed that the growth rates of total aerobic and lactic acid bacteria were significantly (P < 0.05) slower for the formulation containing d-tagatose than those containing l-or d-glucose. Levels of Enterobacteriaceae were initially low and these bacteria did not significantly (P < 0.20) change in the presence of any of the sugars used in the meat formulations. Compared to the control sample containing d-glucose, the shelf life of the chopped and formed ham containing d-tagatose at 10°C was extended by 7 to 10 days. These results indicate that d-tagatose could deter the growth of microorganisms and inhibit the rate of spoilage in a meat product containing carbohydrates.

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40

Vesnina, A. D., A. Y. Prosekov, O. V. Kozlova, M. G. Kurbanova, E. A. Kozlenko y Y. V. Golubtsova. "Development of a probiotic consortium for people with cancer". Proceedings of the Voronezh State University of Engineering Technologies 83, n.º 1 (3 de junio de 2021): 219–32. http://dx.doi.org/10.20914/2310-1202-2021-1-219-232.

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According to the World Health Organization, oncological diseases are a common cause of mortality in the population, as a result of which the development of measures aimed at the prevention of carcinogenesis is urgent. This study is devoted to obtaining a probiotic consortium consisting of bacteria isolated from the gastrointestinal tract of a healthy person, with the further prospect of its use in anticancer therapy in the form of a biologically active additive (BAA) in specialized food products. The object of the study was bacteria isolated from the feces of a healthy person, and consortia based on them. The identification of bacteria and the study of antimicrobial, antioxidant activity, antitumor properties, resistance to antibiotics, acidic medium and bile of bacteria and consortia based on them were carried out according to generally accepted methods. The results of the study are the formation of consortia of isolated and identified bacteria: № 1 – B. bifidum, B. breve, L. plantarum, L. acidophilus, № 2 – B. bifidum, B. breve, L. plantarum, L. fermentum, № 3 – B. breve, L. fermentum, S. salivarius, № 4 – B. breve, L. fermentum, S. thermophiles exhibiting probiotic properties. Consortium № 2 showed antimicrobial activity to the largest number of test cultures; moderate resistance to the largest number of antibiotics – № 1 and № 2; the highest antioxidant activity – № 1, the most pronounced anti-cancer properties in relation to HepG2, LBR2, MDA-MB-231, U87 and Panc-1 – № 4, and to MCF-7 – № 3; the greatest resistance to environments with low acidity and bile – № 2. According to the results of the study, it can be said that the isolated strains, like the consortia based on them, had antimicrobial, antioxidant activity, showed an antitumor effect, resistance to antibiotics, bile and an acidic environment, so that they can be used as probiotic agents in the form of dietary supplements and specialized lactic acid products for the prevention of carcinogenesis.

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41

Obasa, Ken, Frank F. White, John Fellers, Megan Kennelly, Sanzhen Liu, Benjamin Katz, John Tomich, David Moore, Heather Shinogle y Karen Kelley. "A Dimorphic and Virulence-Enhancing Endosymbiont Bacterium Discovered in Rhizoctonia solani". Phytobiomes Journal 1, n.º 1 (enero de 2017): 14–23. http://dx.doi.org/10.1094/pbiomes-08-16-0005-r.

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The ubiquitous soilborne and plant-pathogenic basidiomycete Rhizoctonia solani, although classified as a single species, is a complex of anastomosis groups (AGs) that cause disease in a broad range of higher plants. Here, we investigated the persistent co-isolation of bacteria with R. solani from brown patch-infected, cool-season turfgrasses, and report the presence of endo-hyphal bacteria, related to members in the genus Enterobacter, in an isolate of R. solani AG 2-2IIIB. The intracellular localization of the bacteria was corroborated by fluorescence, confocal and electron microscopy, and DNA analysis. Furthermore, the Enterobacter sp., which is rod-shaped in the free-living form, exists as an L-form (spheroid) within the fungus, a phenomenon not previously reported in endosymbionts. Our findings also indicate that the bacterium is required for full virulence of R. solani on creeping bentgrass and production of wild type levels of the toxin phenylacetic acid in fungal cultures. The possible presence of bacterial endosymbionts in R. solani AG 2-2IIIB may portend the presence of bacteria in additional AGs as well as other Rhizoctonia species, and may help resolve some of the complexities of R. solani pathogenicity. A closely associated bacterium could influence aspects of plant host pathology.

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42

Manome, Akira, Sanae Okada, Tai Uchimura y Kazuo Komagata. "The ratio of L-form to D-form of lactic acid as a criteria for the identification of lactic acid bacteria." Journal of General and Applied Microbiology 44, n.º 6 (1998): 371–74. http://dx.doi.org/10.2323/jgam.44.371.

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43

van Oevelen, Dick, Christina E. Mueller, Tomas Lundälv y Jack J. Middelburg. "Food selectivity and processing by the cold-water coral Lophelia pertusa". Biogeosciences 13, n.º 20 (21 de octubre de 2016): 5789–98. http://dx.doi.org/10.5194/bg-13-5789-2016.

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Abstract. Cold-water corals form prominent reef ecosystems along ocean margins that depend on suspended resources produced in surface waters. In this study, we investigated food processing of 13C and 15N labelled bacteria and algae by the cold-water coral Lophelia pertusa. Coral respiration, tissue incorporation of C and N and metabolically derived C incorporation into the skeleton were traced following the additions of different food concentrations (100, 300, 1300 µg C L−1) and two ratios of suspended bacterial and algal biomass (1 : 1, 3 : 1). Respiration and tissue incorporation by L. pertusa increased markedly following exposure to higher food concentrations. The net growth efficiency of L. pertusa was low (0.08 ± 0.03), which is consistent with its slow growth rate. The contribution of algae and bacteria to total coral assimilation was proportional to the food mixture in the two lowest food concentrations, but algae were preferred over bacteria as a food source at the highest food concentration. Similarly, the stoichiometric uptake of C and N was coupled in the low and medium food treatment, but was uncoupled in the high food treatment and indicated a comparatively higher uptake or retention of bacterial carbon as compared to algal nitrogen. We argue that behavioural responses for these small-sized food particles, such as tentacle behaviour, mucus trapping and physiological processing, are more likely to explain the observed food selectivity as compared to physical–mechanical considerations. A comparison of the experimental food conditions to natural organic carbon concentrations above CWC reefs suggests that L. pertusa is well adapted to exploit temporal pulses of high organic matter concentrations in the bottom water caused by internal waves and downwelling events.

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44

Li, Qun, Ailing Guo, Yi Ma, Ling Liu, Wukang Liu, Yuan Zhong y Yawen Zhang. "Gene Analysis of Listeria monocytogenes Suspended Aggregates Induced by Ralstonia insidiosa Cell-Free Supernatants under Nutrient-Poor Environments". Microorganisms 9, n.º 12 (15 de diciembre de 2021): 2591. http://dx.doi.org/10.3390/microorganisms9122591.

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Listeria monocytogenes is a zoonotic food-borne pathogen. The production of food-borne pathogenic bacteria aggregates is considered to be a way to improve their resistance and persistence in the food chain. Ralstonia insidiosa has been shown to induce L. monocytogenes to form suspended aggregates, but induction mechanisms remain unclear. In the study, the effect of R. insidiosa cell-free supernatants cultured in 10% TSB medium (10% RIS) on the formation of L. monocytogenes suspended aggregates was evaluated. Next, the Illumina RNA sequencing was used to compare the transcriptional profiles of L. monocytogenes in 10% TSB medium with and without 10% RIS to identify differentially expressed genes (DEGs). The result of functional annotation analysis of DEGs indicated that these genes mainly participate in two component system, bacterial chemotaxis and flagellar assembly. Then the reaction network of L. monocytogenes suspended aggregates with the presence of 10% RIS was summarized. The gene-deletion strain of L. monocytogenes was constructed by homologous recombination. The result showed that cheA and cheY are key genes in the formation of suspended aggregates. This research is the preliminary verification of suspended aggregates’ RNA sequencing and is helpful to analyze the aggregation mechanisms of food-borne pathogenic bacteria from a new perspective.

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45

Hastuty, Aerma. "Antibiofilm and antimicrobial activities of papaya (Carica papaya L.) and stevia (Stevia rebaudiana Bertoni) leaf extracts against three biofilm-forming bacteria". Journal of Microbial Systematics and Biotechnology 1, n.º 1 (24 de junio de 2019): 19–29. http://dx.doi.org/10.37604/jmsb.v1i1.18.

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Biofilm is a structural form of a microbial group that is protected by the Extracellular Polymeric Substance (EPS) matrix. The biofilm is considered as the main mediator of infection, and plays a major role in the occurrence of drug resistance. This study was aimed at determining the antimicrobial and antibiofilm activities of papaya (Carica papaya L.) and stevia (Stevia rebaudiana Bertoni) leaf extracts against three biofilm-forming bacteria. The antimicrobial assay showed that papaya leaf extract exhibits higher activity compared to stevia leaf extract in inhibiting the growth of the biofilm-forming bacteria. The optimum condition of papaya leaf extract to inhibit biofilm-forming bacterial growth occurred at 45% and 75% concentrations of the extract (pH 7). A 100% biofilm degradation by papaya leaf extract occurred at pH 6 and pH 9.

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46

Hoffman, Paul S. "Invasion of Eukaryotic Cells byLegionella Pneumophila: A Common Strategy for all Hosts?" Canadian Journal of Infectious Diseases 8, n.º 3 (1997): 139–46. http://dx.doi.org/10.1155/1997/571250.

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Legionella pneumophilais an environmental micro-organism capable of producing an acute lobar pneumonia, commonly referred to as Legionnaires’ disease, in susceptible humans. Legionellae are ubiquitous in aquatic environments, where they survive in biofilms or intracellularly in various protozoans. Susceptible humans become infected by breathing aerosols laden with the bacteria. The target cell for human infection is the alveolar macrophage, in which the bacteria abrogate phagolysosomal fusion. The remarkable ability ofL pneumophilato infect a wide range of eukaryotic cells suggests a common strategy that exploits very fundamental cellular processes. The bacteria enter host cells via coiling phagocytosis and quickly subvert organelle trafficking events, leading to formation of a replicative phagosome in which the bacteria multiply. Vegetative growth continues for 8 to 10 h, after which the bacteria develop into a short, highly motile form called the ‘mature form’. The mature form exhibits a thickening of the cell wall, stains red with the Gimenez stain, and is between 10 and 100 times more infectious than agar-grown bacteria. Following host cell lysis, the released bacteria infect other host cells, in which the mature form differentiates into a Gimenez-negative vegetative form, and the cycle begins anew. Virulence ofL pneumophilais considered to be multifactorial, and there is growing evidence for both stage specific and sequential gene expression. Thus,L pneumophilamay be a good model system for dissecting events associated with the host-parasite interactions.

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47

Reed-Jones, Neiunna L., Sasha Cahn Marine, Kathryne L. Everts y Shirley A. Micallef. "Effects of Cover Crop Species and Season on Population Dynamics of Escherichia coli and Listeria innocua in Soil". Applied and Environmental Microbiology 82, n.º 6 (4 de enero de 2016): 1767–77. http://dx.doi.org/10.1128/aem.03712-15.

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ABSTRACTCover crops provide several ecosystem services, but their impact on enteric bacterial survival remains unexplored. The influence of cover cropping on foodborne pathogen indicator bacteria was assessed in five cover crop/green manure systems: cereal rye, hairy vetch, crimson clover, hairy vetch-rye and crimson clover-rye mixtures, and bare ground. Cover crop plots were inoculated withEscherichia coliandListeria innocuain the fall of 2013 and 2014 and tilled into the soil in the spring to form green manure. Soil samples were collected and the bacteria enumerated. Time was a factor for all bacterial populations studied in all fields (P< 0.001).E. colilevels declined when soil temperatures dipped to <5°C and were detected only sporadically the following spring.L. innocuadiminished somewhat but persisted, independently of season. In an organic field, the cover crop was a factor forE. coliin year 1 (P= 0.004) and forL. innocuain year 2 (P= 0.011). In year 1,E. colilevels were highest in the rye and hairy vetch-rye plots. In year 2,L. innocualevels were higher in hairy vetch-rye (P= 0.01) and hairy vetch (P= 0.03) plots than in the rye plot. Bacterial populations grew (P< 0.05) or remained the same 4 weeks after green manure incorporation, although initial reductions inL. innocuanumbers were observed after tilling (P< 0.05). Green manure type was a factor only forL. innocuaabundance in a transitional field (P< 0.05). Overall, the impacts of cover crops/green manures on bacterial population dynamics in soil varied, being influenced by bacterial species, time from inoculation, soil temperature, rainfall, and tillage; this reveals the need for long-term studies.

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48

Wedhastri, Sri, Dinar Mindrati Fardhani, Siti Kabirun, Jaka Widada, Donny Widianto, Rusdi Evizal y Irfan Dwidya Prijambada. "Legume Nodulating Bacterium, Achromobacter xylosoxidans Found in Tropical Shrub Agroecosystem, Sumatera, Indonesia". Indonesian Journal of Biotechnology 18, n.º 2 (9 de noviembre de 2015): 161. http://dx.doi.org/10.22146/ijbiotech.7879.

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Legume nodulating bacteria (LNB), known also as rhizobia, are soil bacteria, which are able to form rootnodules and fi x nitrogen in the leguminous plants. The LNB availability in the soil depends on the type ofagroecosystem, where plant grows. In this study, we isolated LNB from the shrub agroecosystem in Sumatera,Indonesia, and obtained four selected bacterial strains. Among them, the isolate UGM48a formed root nodulein Macroptilium atropurpureum and showed highest number of nitrogenase activity. UGM48a also contains nifHand nodA genes. An analysis of the PCR-amplifi ed 16S rDNA and BLASTn analysis showed that UGM48adisplayed 96% similarity with Achromobacter xylosoxidans. In addition, UGM48a were successfully nodulatedGlycine max (L.) merr var. wilis. This is the fi rst report detecting A. xylosoxidans as nodule-forming species forGlycine max possesing the positive copy of nodA gene. Keywords : Legume Nodulating Bacteria, shrub agroecosystem, Achromobacter xylosoxidans, nodA, Glycine max

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49

Malkova, Angelina, Ivan Evdokimov, Maxim Shirmanov, Alena Irkitova y Dina Dudnik. "Development of a microbiological preparation for crops based on Bacillus pumilus strains". BIO Web of Conferences 36 (2021): 07012. http://dx.doi.org/10.1051/bioconf/20213607012.

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Data of the microbial biopreparation development for protection and crop growth stimulation on the Bacillus bacteria basis are presented. Three B. pumilus strains isolated from the Altai region (the Russian Federation) plants rhizosphere were selected as active components of the bacterial preparation. L-bulone was chosen as the nutrient medium for flasks cultivation of the inoculum. A molasses-based nutrient medium was used to incubate the bacilli in a 15-liter fermenter. The finished microbial preparation was obtained in dry form. The biopreparation is a powder consisting of a lyophilically dried concentrates mixture of genus Bacillus spores. Bacilli biomass were pre-mixed with a protective medium based on gelatin and sucrose. The final number of bacteria in the microbial preparation is 1.29(±0.30) ×1012 CFU/g.

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50

Provencher, Cathy, GisÃ¯Â¿Â½le LaPointe, StÃ¯Â¿Â½phane Sirois, Marie-Rose Van Calsteren y Denis Roy. "Consensus-Degenerate Hybrid Oligonucleotide Primers for Amplification of Priming Glycosyltransferase Genes of the Exopolysaccharide Locus in Strains of the Lactobacillus casei Group". Applied and Environmental Microbiology 69, n.º 6 (junio de 2003): 3299–307. http://dx.doi.org/10.1128/aem.69.6.3299-3307.2003.

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ABSTRACT A primer design strategy named CODEHOP (consensus-degenerate hybrid oligonucleotide primer) for amplification of distantly related sequences was used to detect the priming glycosyltransferase (GT) gene in strains of the Lactobacillus casei group. Each hybrid primer consisted of a short 3′ degenerate core based on four highly conserved amino acids and a longer 5′ consensus clamp region based on six sequences of the priming GT gene products from exopolysaccharide (EPS)-producing bacteria. The hybrid primers were used to detect the priming GT gene of 44 commercial isolates and reference strains of Lactobacillus rhamnosus, L. casei, Lactobacillus zeae, and Streptococcus thermophilus. The priming GT gene was detected in the genome of both non-EPS-producing (EPS−) and EPS-producing (EPS+) strains of L. rhamnosus. The sequences of the cloned PCR products were similar to those of the priming GT gene of various gram-negative and gram-positive EPS+ bacteria. Specific primers designed from the L. rhamnosus RW-9595M GT gene were used to sequence the end of the priming GT gene in selected EPS+ strains of L. rhamnosus. Phylogenetic analysis revealed that Lactobacillus spp. form a distinctive group apart from other lactic acid bacteria for which GT genes have been characterized to date. Moreover, the sequences show a divergence existing among strains of L. rhamnosus with respect to the terminal region of the priming GT gene. Thus, the PCR approach with consensus-degenerate hybrid primers designed with CODEHOP is a practical approach for the detection of similar genes containing conserved motifs in different bacterial genomes.

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