Relevant bibliographies by topics / Gram-positive bacteria

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Gram-positive bacteria'

Author: Grafiati
Published: 4 June 2021
Last updated: 10 March 2023

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Journal articles on the topic "Gram-positive bacteria"

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Milligan, Gregg N. "GRAM-POSITIVE BACTERIA." Shock 9, no. 3 (March 1998): 233. http://dx.doi.org/10.1097/00024382-199803000-00014.

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Niranjan, Pankaj Singh, Chandrul Koushal, and S. K. Jain. "Pharmacological investigation of leaves of Polypodium decumanum for anti-bacterial activity against gram-positive and gram-negative bacteria." International Journal of Research and Development in Pharmacy & Life Sciences 06, no. 04 (July 2017): 2685–88. http://dx.doi.org/10.21276/ijrdpl.2278-0238.2017.6(4).2685-2688.

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Putri, Neisya Intan Cahyaningtyas Agung, Ramadhani Ramadhani, and Eddy Bagus Wasito. "Gram Negative Bacteria (Escherichia coli) Win Against Gram Positive Bacteria (Staphylococcus aureus) in The Same Media." Biomolecular and Health Science Journal 4, no. 2 (October 30, 2021): 113. http://dx.doi.org/10.20473/bhsj.v4i2.30177.

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Introduction: Biodiversity of the microorganism in Indonesia lead to the large amount of patient with infection. Human can get infected in two different place, with different kind of bacteria that cause the infection. This may lead to bacteremia without knowing which bacteria type whose causing it, either the Gram positive or Gram negative bacteria, whereas the treatment of this two types of bacteria are different. The aim of this study is to determine the doubling time of the Gram positive and Gram negative bacteria when they are grown in the same lesion and the kinds of bacteria that we need to eliminate first.Methods: Staphylococcus aureus and Escherichia coli bacteria were used as samples in this study. Bacterial culture in nutrient broth with 0.5 OD turbidity were mixed then incubated in incubator with 35˚C. Every one hour within 24 hour, 0.01 ml of bacterial culture was taken in serial dilutionover time, varying between 106 – 1012, . It was then planted in nutrient agar plate with droplets technique. After it had been incubated for 24 hours, we counted the Colony Forming Unit per ml (CFU/ml) to time, then the doubling time of the bacteria. The result were then compared between the Staphylococcus aureus and Escherichia coli group.Results: Two tailed t-test result of the doubling time between Staphylococcus aureus dan Escherichia coli was < 0,05 (p=0,000) wich means that there is significant difference of the doubling time between Staphylococcus aureus (24,35 ± 2,23 munites), and Escherichia coli (18,37 ± 0,50 minutes). When grown in the same media, Gram positive bacteria (Staphylococcus aureus) had slower doubling time than Gram negative bacteria (Escherichia coli) as much as 1.32 times.Conclusion: In bacteremia with two possible kinds of bacterial suspect, we need to eliminate the Gram negative bacteria first.
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Hing, Jan Nie, Bor Chyan Jong, Pauline Woan Ying Liew, Rashid Elly Ellyna, and Shuhaimi Shamsudin. "Gamma Radiation Dose-Response of Gram-Positive and Gram-Negative Bacteria." Malaysian Applied Biology 51, no. 5 (December 26, 2022): 107–12. http://dx.doi.org/10.55230/mabjournal.v51i5.2370.

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Bacterial mutagenesis induced through gamma irradiation is one of the techniques for strain improvement. The DNA changes caused by radiation and reactive oxygen species created from water radiolysis induced bacterial mutagenesis. There is always a constant demand for better quality strains from the bioprocessing industries to speed up production and increase yield. Bacillus strains are Gram-positive bacteria whereas Escherichia coli is a Gram-negative bacteria; they are all model organisms used by the bioprocessing industries. This study investigates the effect of acute gamma irradiation on Gram-positive Bacillus megaterium NMBCC50018, Bacillus subtilis NMBCC50025 and Gram-negative Escherichia coli. Samples were irradiated in Gamma Cell Acute Irradiation Facility at Malaysian Nuclear Agency with irradiation doses from 0.1 kGy to 2.1 kGy. The radiation sources were from two Cesium-137 sealed sources. Dose responses are crucial information for bacterial mutagenesis studies. The survival curves of viable bacterial cell count versus radiation doses were plotted to determine dose-response and lethal dose, 50% (LD50). Viable cells reduce as irradiation doses increase. The LD50 for Bacillus megaterium NMBCC50018, Bacillus subtilis NMBCC50025 and Escherichia coli were 1.2 kGy, 0.2 kGy, and 0.03 kGy, respectively. Bacillus megaterium NMBCC50018 was most resistant to gamma radiation. Dose responses between Gram-positive and Gram-negative bacteria were concluded to be different.
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Vila Domínguez, Andrea, Rafael Ayerbe Algaba, Andrea Miró Canturri, Ángel Rodríguez Villodres, and Younes Smani. "Antibacterial Activity of Colloidal Silver against Gram-Negative and Gram-Positive Bacteria." Antibiotics 9, no. 1 (January 19, 2020): 36. http://dx.doi.org/10.3390/antibiotics9010036.

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Due to the emergence of antimicrobial resistance, new alternative therapies are needed. Silver was used to treat bacterial infections since antiquity due to its known antimicrobial properties. Here, we aimed to evaluate the in vitro activity of colloidal silver (CS) against multidrug-resistant (MDR) Gram-negative and Gram-positive bacteria. A total of 270 strains (Acinetobacter baumannii (n = 45), Pseudomonas aeruginosa (n = 25), Escherichia coli (n = 79), Klebsiella pneumoniae (n = 58)], Staphylococcus aureus (n = 34), Staphylococcus epidermidis (n = 14), and Enterococcus species (n = 15)) were used. The minimal inhibitory concentration (MIC) of CS was determined for all strains by using microdilution assay, and time–kill curve assays of representative reference and MDR strains of these bacteria were performed. Membrane permeation and bacterial reactive oxygen species (ROS) production were determined in presence of CS. CS MIC90 was 4–8 mg/L for all strains. CS was bactericidal, during 24 h, at 1× and 2× MIC against Gram-negative bacteria, and at 2× MIC against Gram-positive bacteria, and it did not affect their membrane permeabilization. Furthermore, we found that CS significantly increased the ROS production in Gram-negative with respect to Gram-positive bacteria at 24 h of incubation. Altogether, these results suggest that CS could be an effective treatment for infections caused by MDR Gram-negative and Gram-positive bacteria.
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Souza, Bianca Mendes, Thiago Luiz de Paula Castro, Rodrigo Dias de Oliveira Carvalho, Nubia Seyffert, Artur Silva, Anderson Miyoshi, and Vasco Azevedo. "σECFfactors of gram-positive bacteria." Virulence 5, no. 5 (June 12, 2014): 587–600. http://dx.doi.org/10.4161/viru.29514.

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Hynes, Wayne L., and Sheryl Lynne Walton. "Hyaluronidases of Gram-positive bacteria." FEMS Microbiology Letters 183, no. 2 (February 2000): 201–7. http://dx.doi.org/10.1111/j.1574-6968.2000.tb08958.x.

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Sutcliffe, I. C., and R. R. Russell. "Lipoproteins of gram-positive bacteria." Journal of bacteriology 177, no. 5 (1995): 1123–28. http://dx.doi.org/10.1128/jb.177.5.1123-1128.1995.

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Jack, R. W., J. R. Tagg, and B. Ray. "Bacteriocins of gram-positive bacteria." Microbiological reviews 59, no. 2 (1995): 171–200. http://dx.doi.org/10.1128/mmbr.59.2.171-200.1995.

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Jack, R. W., J. R. Tagg, and B. Ray. "Bacteriocins of gram-positive bacteria." Microbiological reviews 59, no. 2 (1995): 171–200. http://dx.doi.org/10.1128/mr.59.2.171-200.1995.

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Dissertations / Theses on the topic "Gram-positive bacteria"

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Woo, Kei-sheng Gibson, and 吳基昇. "Molecular epidemiology of anaerobic gram-positive bacilli bacteremia and discovery of six novel anaerobic gram-positive bacilli." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29762984.

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Gally, David Lawrence. "Cell wall assembly in gram positive bacteria." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287465.

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Valappil, Sabeel Padinhara. "Production of polyhydroxyalkanoates by gram positive bacteria." Thesis, University of Westminster, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434414.

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Hayhurst, Emma. "Peptidoglycan structure and dynamics in gram positive bacteria." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434615.

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Wang, Lihui. "Sensing of gram positive bacteria in drosophila immunity." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670165.

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Johansson, Per. "Genetics of tetrapyrrole synthesis in gram-positive bacteria." Lund : Lund University, 1999. http://catalog.hathitrust.org/api/volumes/oclc/68944808.html.

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Wheeler, Richard. "Peptidoglycan architecture and dynamics in Gram-positive bacteria." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/2741/.

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The major structural determinant of most bacterial cells is the peptidoglycan layer, a network (the sacculus) of glycan strands cross-linked by short peptide stems which encompasses the entire bacterium. However the architecture of peptidoglycan, which must accommodate both the structural requirements of the cell and the dynamic processes of growth and division, is poorly understood. Most architectural studies have addressed the peptidoglycan of rod-shaped bacteria. The architecture in Gram-positive cocci and ovococci is largely uncharacterised, In this study, atomic force microscopy (AFM) of purified sacculi of three species of ovococcus was combined with biochemical analysis and super resolution fluorescence microscopy. A model was developed in which incorporation of long glycan strands from a single mid-cell focus results in preferential orientation, parallel to the short axis of the cell. AFM and fluorescence microscopy of the coccoid bacterium Staphylococcus aureus revealed a dynamic peptidoglycan architecture of rings and knobbles, growth by peptidoglycan maturation, and a system of heritable peptidoglycan ribs. Ribs may provide a structural mechanism for coordinating orthogonal division on three planes. We hypothesised cell wall growth occurs via the activity of N-acetyl-β-D-glucosaminidases. Four putative glucosaminidases were identified, with SagB found to have a major role in glycan strand length determination. Hydrolysis of the septal cross-wall by glucosaminidase activity was required for spherical shape, suggesting a novel mechanism of growth by hydrolysis. My work has highlighted diverse and elegant peptidoglycan architectures, adapted to meet the unique mechanical requirements of bacteria with different morphologies and strategies for growth and division.
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Hreggvidsson, Gudmundur Oli. "Cytochromes c and the evolution of Gram positive bacteria." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/14116.

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The content and cellular location of cytochromes in Bacillus azotoformans was examined under aerobic and denitrifying anaerobic conditions. An abundance of cytochromes was expressed. Two cytochromes were induced under aerobic conditions, one of which was only expressed under conditions of high aeration. One cytochrome, a b-type cytochrome, may be induced under denitrifying conditions. Cytochromes common to both pathways appear to be expressed in similar amounts per unit cell weight. Both c- and b-type cytochromes from B. azotoformans appear to be membrane bound, as they were only detected in membrane fractions. Different methods for releasing cytochromes from cell membranes were tried. Only extraction with detergents and mild proteolytic treatment were successful. Four different membrane bound cytochromes from Bacillus azotoformans, designated P1-c552, P2-c551, P3&P4-c555 and P5-c552, were isolated and purified. The bases of classification of Class I cytochromes c are examined and revisions are suggested to the existing classification schemes. The evolutionary implications of the distribution of the proposed cytochrome c groups in the phylogenetic eubacterial tree, based on 16sRNA analyses, are discussed. The past and present ideas about the evolution of the phylum of Gram positive bacteria are presented and discussed in the light of the present sequence information of cytochromes c and other electron transport proteins. The electron transport pathway in the genus Bacillus is compared with its counterparts in distantly related bacteria. The significance of observed similarities and differences, in types of cytochromes and composition, for the elucidation of the evolutionary history of the Gram positive phylum as well as for eubacteria in general, is emphasised.
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Lee, Wan-Jing. "Isolation and characterisation of phages infecting gram positive food bacteria." Thesis, University of Canterbury. School of Biological Sciences, 2008. http://hdl.handle.net/10092/3429.

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Bacteriophage (phage), virus of bacteria, has been proposed as a mean to inactivate bacteria that are pathogens of humans. Applied prophylatically to food, phage might decrease the numbers of potential pathogens we ingest. Much active research on using the phages of bacteria to control Gram negative foodborne pathogens are described in the literatures, but comparatively little research describes the phages of Gram positive bacteria and their use as biocontrol agents on food. In this work, previous undescribed phages, able to infect Bacillus cereus and Listeria monocytogenes, were isolated from soil and ruminants faecal material, respectively. As the first step in assessing their potential as biocontrol agents, the isolated phages were purified, concentrated and characterised (albeit to different degrees). The Bacillus phages had a narrow host range while the Listeria phages had a broad host range. Listeria phages also infected L. monocytogenes 2000/47, a strain which recurs in New Zealand clinical cases. Both Bacillus and Listeria phages appeared to be of the Myoviridae family judging by their structure in electron micrographs. The Bacillus FWLBc1 and FWLBc2 phages were lytic phages with a latent period of 106 and 102 min at 37°C, and an average burst size of 322 and 300 phages per infected cell, respectively. Moreover, they both had genomes of approximately 134 kb. All newly isolated and characterized phages were chloroform resistant and survived storage better at 4°C than at room or freezing temperatures. Bacillus phages significantly reduced the bacterial population in mashed potatoes within 24 h at room temperature, when applied at a phage to host ratio of 1000. Listeria phages rapidly inactivated the host population to a low optical density. The findings of this thesis will add to the current knowledge of phages in the context of various environmental conditions for different bacteria and will demonstrate the potential of phages as food safety biocontrol agents.
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Qazi, Saara N. A. "Development of reporter genes for use in Gram positive bacteria." Thesis, University of Nottingham, 1999. http://eprints.nottingham.ac.uk/13028/.

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Green fluorescent protein (gfp) and bacterial luminescence (lux) reporter genes have been used to construct a variety of reporter plasmids for Gram positive bacteria with the aim of using these for bacterial localisation and gene expression studies. The native gfp and luxCDABE genes were cloned into a shuttle vector and the resulting plasmids used to transform Listeria monocytogenes. However, the bacterial populations were found to be weakly fluorescent or luminescent compared to E. coli harbouring the same plasmids. When L. monocytogenes expressing gfp were examined by fluorescence microscopy, only a small proportion of the population was seen to fluoresce. This phenomenon was observed regardless of the gfp variant used in the cloning procedure. However, when gfp3 was placed downstream of PxylA, slightly more individual fluorescent cells were observed compared to when gfp3 was expressed from Pxyn, but the majority of the population was still non-fluorescent. Northern blot analysis and subsequent analysis by SDS PAGE and immunoblotting lead to the supposition that translation of gfp was limiting in L. monocytogenes. A variety of factors could potentially lead to poor translation of the protein, for example poor codon usage, the presence of a ribosome stall site, or poor initiation of translation by the ribosomes. These were all investigated in tum to determine why translation of gfp3 was limiting. Modification of the translational initiation region of gfp3, resulted in a homogeneously fluorescent L. monocytogenes population when the modified gene was expressed from PxylA. Individual lux genes, luxA, luxC and luxE were also translationally enhanced in a similar way to gfp3, and reorganised into an operon where the luciferase genes were adjacent to, but separate from the aldehyde genes. This engineered luxABCDE operon was also expressed from PxylA and highly luminescent populations of L. monocytogenes and Staphylococcus aureus obtained. Having optimised translation for expression III Gram positive bacteria, these reporters were used to construct a variety of reporter plasmids that were successfully employed to observe the intracellular invasion and to monitor agr expression in S. aureus.
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Books on the topic "Gram-positive bacteria"

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Pozzi, Gianni, and Jeremy M. Wells, eds. Gram-Positive Bacteria. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7.

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A, Fischetti Vincent, and American Society for Microbiology, eds. Gram-positive pathogens. 2nd ed. Washington, D.C: ASM Press, 2006.

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Holzapfel, W. H. N. Genera of lactic acid bacteria. [S.l.]: Springer, 2012.

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Antoine, Danchin, ed. Genomics of GC-rich gram-positive bacteria. Norfolk, U.K: Caister Academic Press, 2002.

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Backert, Steffen, and Elisabeth Grohmann, eds. Type IV Secretion in Gram-Negative and Gram-Positive Bacteria. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-75241-9.

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Sonenshein, Abraham L., James A. Hoch, and Richard Losick, eds. Bacillus subtilis and Other Gram-Positive Bacteria. Washington, DC, USA: ASM Press, 1993. http://dx.doi.org/10.1128/9781555818388.

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Meissner, Daniel. Vergleichende Analyse der Sec- und Tat-abhängigen sekretorischen Proteingewinnung mit Gram-positiven Bakterien als Wirtsorganismen. Jülich: Forschungszentrum Jülich GmbH, Zentralbibliothek, 2006.

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1940-, Reizer Jonathan, and Peterkofsky Alan 1930-, eds. Sugar transport and metabolism in gram-positive bacteria. Chichester, West Sussex: Ellis Horwood, 1987.

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Hawley, Louise B. High-yield microbiology and infectious diseases. Philadelphia: Lippincott Williams & Wilkins, 2000.

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Bagnoli, Fabio, and Rino Rappuoli, eds. Protein and Sugar Export and Assembly in Gram-positive Bacteria. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56014-4.

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Book chapters on the topic "Gram-positive bacteria"

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Wells, Jeremy M., and Gianni Pozzi. "An Overview of Gram-Positive Bacteria as Vaccine Vehicles for Mucosal Immunization." In Gram-Positive Bacteria, 1–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7_1.

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Rescigno, Maria, Stefania Citterio, and Paola Ricciardi-Castagnoli. "Dendritic Cells as Targets for Mucosal Immunization." In Gram-Positive Bacteria, 9–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7_2.

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Pozzi, Gianni, Marco R. Oggioni, and Donata Medaglini. "Recombinant Streptococcus gordonii as a Live Vehicle for Vaccine Antigens." In Gram-Positive Bacteria, 35–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7_3.

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Ståhl, Stefan, Patrik Samuelson, Marianne Hansson, Christine Andréoni, Liliane Goetsch, Christine Libon, Sissela Liljeqvist, et al. "Development of Non-Pathogenic Staphylococci as Vaccine Delivery Vehicles." In Gram-Positive Bacteria, 61–81. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7_4.

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Chamberlain, Lisa, Jeremy M. Wells, Karen Robinson, Karin Schofield, and Richard Le Page. "Mucosal Immunization with Recombinant Lactococcus lactis." In Gram-Positive Bacteria, 83–106. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7_5.

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Rush, Catherine M., Annick Mercenier, and Gianni Pozzi. "Expression of Vaccine Antigens in Lactobacillus." In Gram-Positive Bacteria, 107–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7_6.

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Guzmán, Carlos A., Siegfried Weiss, and Trinad Chakraborty. "Listeria monocytogenes — A Promising Vaccine Carrier to Evoke Cellular Immune Responses." In Gram-Positive Bacteria, 145–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-662-07548-7_7.

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Tuwairqi, Khaled. "Gram-Positive Bacteria." In Encyclopedia of Ophthalmology, 1–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-35951-4_797-1.

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Grossman, Marc E., Lindy P. Fox, Carrie Kovarik, and Misha Rosenbach. "Gram-Positive Bacteria." In Cutaneous Manifestations of Infection in the Immunocompromised Host, 223–43. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-1578-8_12.

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Amils, Ricardo. "Gram-Positive Bacteria." In Encyclopedia of Astrobiology, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_664-2.

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Conference papers on the topic "Gram-positive bacteria"

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Sysolyatina, E. V., M. A. Yurova, A. Y. Mukhachev, M. A. Danilova, M. E. Grushin, A. V. Petryakov, N. I. Trushkin, S. A. Ermolaeva, and Y. S. Akishev. "The bactericidal effect of a positive and negative corona on Gram-positive and Gram-negative bacteria." In 2012 IEEE 39th International Conference on Plasma Sciences (ICOPS). IEEE, 2012. http://dx.doi.org/10.1109/plasma.2012.6383778.

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Chamidah, A., Hardoko, and A. A. Prihanto. "Antibacterial activities of β-glucan (laminaran) against gram-negative and gram-positive bacteria." In 2ND INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS AND MATERIAL ENGINEERING (ICCMME 2017). Author(s), 2017. http://dx.doi.org/10.1063/1.4983422.

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Karaman, Didem Sen, and M. Baran Karakaplan. "Effect of zinc oxide nanoparticles on the growth of gram-positive and gram-negative bacteria." In 2021 Medical Technologies Congress (TIPTEKNO). IEEE, 2021. http://dx.doi.org/10.1109/tiptekno53239.2021.9632900.

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Kumalasari, Yeni Indra, Agung Dian Kharisma, and Sri Yuwantiningsih. "Potential of Karimunjawa Island’s Plants as Antibiotic-Producing Endophytic Bacteria Sources." In The 2nd International Conference on Technology for Sustainable Development. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/p-kv25ou.

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Endophytic bacteria have a great potential to be applied as biofertilizers and biopesticides, but their information as a source of antibiotics still needs to be developed and explored. The aim of this study was to investigate the potential sources of antibiotics in endophytic bacteria isolated from the stems of Setigi, Wahong, Bongko, Kalimosodo, Dewandaru, and Legundi plants on Karimunjawa Island. Molecular approaches were performed to isolate, characterize, and identify bacterial endophytes as potential antibiotic sources by plate assay and 16S rRNA gene sequence analysis. Dewandaru isolate was identified as gram-negative bacteria, whereas; gram-positive bacteria were detected in other isolates. Moreover, Setigi and Dewandaru isolates showed the highest level to inhibit the growth of Fusarium sp and displayed 99% similarity with antibiotic-producing bacteria, namely Bacillus pumilus and Bacillus cereus, respectively. These results indicate the possibility of antibiotic activities by Setigi and Dewandaru isolated. Therefore, it is assumed that both Setigi and Dewandaru isolates potentially appeared as new antibiotics sources from local plants. This study provides novel insight into the future production of novel antibiotics derived from plant-associated endophytic bacterial as a strategy for increasing the application of natural compounds to control plant diseases in agriculture.
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GADDIPATI, S. R., T. M. PEREHINEC, S. N. A. QAZI, C. E. D. REES, and P. J. HILL. "BIVALENT FLUORESCENT REPORTERS FOR GENE EXPRESSION STUDIES IN GRAM-POSITIVE BACTERIA." In Chemistry, Biology and Applications. WORLD SCIENTIFIC, 2007. http://dx.doi.org/10.1142/9789812770196_0047.

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Vulto, P., C. Hermann, P. Zahn, U. Maier, G. Dame, and G. A. Urban. "A microchip for automated extraction of RNA from Gram-positive bacteria." In TRANSDUCERS 2009 - 2009 International Solid-State Sensors, Actuators and Microsystems Conference. IEEE, 2009. http://dx.doi.org/10.1109/sensor.2009.5285553.

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Khair, Nedaa Kamalalden. "Activity of Antibiotic Producing Bacteria Isolated from Rhizosphere Soil Region of Different Medicinal Plants." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0093.

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The rhizosphere soil of medicinal plants is rich in microorganisms that develop antibiotics as natural mechanism of protection against other microbes that live in their vicinity. The present study aims to explore the production of antibacterial agents from rhizosphere soil bacteria of 11 medicinal plants and determine their activity against Gram-negative (Pseudomonas aeruginosa, Escherichia coli) and Gram-positive (Bacillus cereus, Staphylococcus aureus) bacteria. Soil samples were collected and used to isolate antibiotic producing bacteria (APB). Those isolates (108) were first tested using Cross-streak method against test bacteria. Then, isolates that showed a positive antibacterial effect (12) were tested by antibiotic susceptibility test (AST) of their cell free supernatant (CFS) and their extracellular and intracellular secondary metabolites extraction which gave positive results. Staphylococcus aureus found to be the most sensitive test bacteria with inhibitory zones ranging from 13.5 - 19 mm. Moreover, combinatorial effect of isolates CFS with two organic acids (3% Acetic acid and 0.4 mg/ml Acetylsalicylic acid), two commercial antibiotics (0.016 mg/ml Augmentin and 0.128 mg/ml Doxycycline), and two pure antibiotics (10 mcg/disk Penicillin and 25mcg/disk Carbenicillin) was in vitro evaluated using AST. The combinations of CFS-carbenicillin showed a marked synergistic activity against all test bacteria. The presence of possible antibacterial agents as acetic acid, lactic acid and citric acid in CFS of APB was confirmed by HPLC analysis. Ultimately, in vitro antibacterial study for rhizosphere soil bacteria in this work suggests the possibility of using these bacterial metabolites in clinical infections caused by selected test bacteria, especially when they combine with antibiotics or organic acids.
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Batsalova, Tsvetelina, Dzhemal Moten, Ivan Butenko, Balik Dzhambazov, and Alexander Vasilkov. "BIOLOGICAL AND PHYSICOCHEMICAL PROPERTIES OF GOLD AND IRON NANOPARTICLES PRODUCED BY GREEN SYNTHESIS METHOD." In 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022/6.1/s24.02.

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Gold and iron nanoparticles were generated via environmentally safe metal-vapor synthesis method applying acetone or toluene as organic dispersion medium. Biological properties of the nanoparticles were analyzed by the agar disc diffusion method using Gram-positive and Gram-negative bacteria and via in vitro cytotoxicity assays with different human cell lines. The obtained results revealed distinct biological activity profiles of the studied specimens. Fe nanoparticles (Fe NPs) demonstrated inhibitory effects against both Gram-positive and Gram-negative bacteria. Au nanoparticles (Au NPs) produced in acetone as organic dispersion medium reduced the growth of E. coli, but showed lower activity against the Gram-positive bacterium B. cereus. Au NPs derived from toluene organosol demonstrated the lowest level of antibacterial activity. In vitro analyses with human cells indicated mild cytotoxic effects of Au NPs against all tested cell lines. Fe NPs demonstrated time- and concentration-dependent cytotoxicity against colon adenocarcinoma cells. Iron nanoparticles derived from acetone organosol did not induce negative effect on noncancerous human cells, which indicates a good biocompatibility potential. Their physicochemical properties were characterized by transmission and scanning electron microscopy (TEM, SEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). TEM observations demonstrated that Au NPs and Fe NPs have average sizes of 8.3 nm and 1.8 nm. Characteristics of the photoelectron spectra showed that gold is in the state of Au0, and the spectrum of iron is close in shape to the spectrum of Fe3O4.
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Ramachandran, Rekhachandran Prasanna, Archana Valliyamma, Nitha Nellithanathu Thomas, Mangalaraja Ramalinga Viswanathan, Boby Theophilofe Edwin, and Anas Shereef. "Light mediated, switchable, antibacterial activity of cerium dioxide nanoparticles on gram positive and gram negative bacteria." In 16TH INTERNATIONAL CONFERENCE ON CONCENTRATOR PHOTOVOLTAIC SYSTEMS (CPV-16). AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0029978.

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Mishra, Bhoopesh, Jeremy B. Fein, Maxim I. Boyanov, Shelly D. Kelly, Kenneth M. Kemner, and Bruce A. Bunker. "Comparison of Cd Binding Mechanisms by Gram-Positive, Gram-Negative and Consortia of Bacteria Using XAFS." In X-RAY ABSORPTION FINE STRUCTURE - XAFS13: 13th International Conference. AIP, 2007. http://dx.doi.org/10.1063/1.2644520.

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Reports on the topic "Gram-positive bacteria"

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Bezerra, Alexandre Sacchetti, Flavia Altheman Loureiro, Carla Maria Pasquareli Vazquez, Afonso Cesar Polimanti, and Rafi Felicio Bauab Dauar. Empiric Treatment of Foot Infection in Patients with Severe Diabetes. Science Repository, December 2021. http://dx.doi.org/10.31487/j.jicoa.2021.04.04.

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Background: Despite being treated with antibiotics of broad spectrum recommended by International Consensus, severe diabetic patients with lower limb infection do not present a positive clinical evolution during empirical treatment. This study’s bacterial profile was analysed and compared with other worldwide hospital centers. Objective: To confirm the need of an individualized empirical treatment for severe diabetic patients with foot infection. Methods: Retrospective analysis of cultures and antibiograms of severe diabetic patients admitted by foot infection. Results: The results were consistent with the socioeconomic realities of developing countries. Gram-negative bacteria (52,11%) were present in most bone cultures. Results presented a high incidence of Enterococcus faecalis in both gram-positive (21,2%) and polymicrobial (34,7%) samples. Bacterial resistance with the use of ordinary antibiotics in the statistical analysis was high. Conclusion: The community infections should undergo broad spectrum empirical therapy combining amikacin (80,43%) or meropenem (72,00%) with gram-negative and vancomycin (100%) or teicoplanin (90,00%) or linezolid (74,19%) with gram-positive.
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Hannan, Trisha. Characterization of gram-positive bacterial isolates from burn victims. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.3053.

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Choudhary, Ruplal, Victor Rodov, Punit Kohli, John D. Haddock, and Samir Droby. Antimicrobial and antioxidant functionalized nanoparticles for enhancing food safety and quality: proof of concept. United States Department of Agriculture, September 2012. http://dx.doi.org/10.32747/2012.7597912.bard.

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General concept. The reported 1-year study tested the feasibility ofpreparing antimicrobial and antioxidant nanoparticlesfunctionalized with natural phenolic compounds, as a first step to reach the ultimate goal - improving safely and quality of foods by developing novel antimicrobial and antioxidant food-contacting materials. The secondary objectives of the study were (a) selecting the most promising phenoliccompounds, (b) building nanoparticles with the selected phenolicgrafted on their Surface, and (c) testing antimicrobial and antioxidant properties of these particles. The study was expected to provide a " go/no go" decision as concerning the prospects of phenolic- bound nanoparticles as antimicrobial and antioxidant agents. Results. In course of the feasibility study, curucminwas chosen as the most promising phenoliccompound due to its high antibacterial activity exceeding other tested compounds by at leas one order of magnitude. Lipsome-typephospholipid/polydiacetylene(PDA) nanoparticlesfunctionalizedwith curcuminwere successfully built. The pitfall of limited curcumin amount that could be covalently bound to theparticle surface was circumvented by inclusion of curcunun in the liposome body. It was suggested onthe basis of fluorescence spectroscopy that curcuminwas bound by hydrophobic forces in the bi1ayer periphery of the Liposomesand therefore mightexert a contact effect on microorganisms. The curcumin­ functionalizednanoparticles(CFN) were shown to have a strong bactericidal activity towards both Gram-negative (E. coli) and Gram-positive (B. ce,·e11s) bacteria, but only limited effect against yeast. Furthermore, beyond the originallyplanned objectives, preliminary trials showed that CFN could be bound to silanized glass surface rendering aנבtiנnicrobial activity to the glass. Tnaddition, the particles showed antioxidantcapacity. Tberefore, it ,vas co11cluded tlוattlוeaims of tlוefeasibility study bad been successfully reached an
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Choudhary, Ruplal, Victor Rodov, Punit Kohli, Elena Poverenov, John Haddock, and Moshe Shemesh. Antimicrobial functionalized nanoparticles for enhancing food safety and quality. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7598156.bard.

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Original objectives The general goal of the project was to utilize the bactericidal potential of curcumin- functionalizednanostructures (CFN) for reinforcement of food safety by developing active antimicrobial food-contact surfaces. In order to reach the goal, the following secondary tasks were pursued: (a) further enhancement of the CFN activity based on understanding their mode of action; (b) preparing efficient antimicrobial surfaces, investigating and optimizing their performance; (c) testing the efficacy of the antimicrobial surfaces in real food trials. Background to the topic The project dealt with reducing microbial food spoilage and safety hazards. Cross-contamination through food-contact surfaces is one of the major safety concerns, aggravated by bacterial biofilm formation. The project implemented nanotech methods to develop novel antimicrobial food-contact materials based on natural compounds. Food-grade phenylpropanoidcurcumin was chosen as the most promising active principle for this research. Major conclusions, solutions, achievements In agreement with the original plan, the following research tasks were performed. Optimization of particles structure and composition. Three types of curcumin-functionalizednanostructures were developed and tested: liposome-type polydiacetylenenanovesicles, surface- stabilized nanoparticles and methyl-β-cyclodextrin inclusion complexes (MBCD). The three types had similar minimal inhibitory concentration but different mode of action. Nanovesicles and inclusion complexes were bactericidal while the nanoparticlesbacteriostatic. The difference might be due to different paths of curcumin penetration into bacterial cell. Enhancing the antimicrobial efficacy of CFN by photosensitization. Light exposure strengthened the bactericidal efficacy of curcumin-MBCD inclusion complexes approximately three-fold and enhanced the bacterial death on curcumin-coated plastic surfaces. Investigating the mode of action of CFN. Toxicoproteomic study revealed oxidative stress in curcumin-treated cells of E. coli. In the dark, this effect was alleviated by cellular adaptive responses. Under light, the enhanced ROS burst overrode the cellular adaptive mechanisms, disrupted the iron metabolism and synthesis of Fe-S clusters, eventually leading to cell death. Developing industrially-feasible methods of binding CFN to food-contact surfaces. CFN binding methods were developed for various substrates: covalent binding (binding nanovesicles to glass, plastic and metal), sonochemical impregnation (binding nanoparticles to plastics) and electrostatic layer-by-layer coating (binding inclusion complexes to glass and plastics). Investigating the performance of CFN-coated surfaces. Flexible and rigid plastic materials and glass coated with CFN demonstrated bactericidal activity towards Gram-negative (E. coli) and Gram-positive (Bac. cereus) bacteria. In addition, CFN-impregnated plastic material inhibited bacterial attachment and biofilm development. Testing the efficacy of CFN in food preservation trials. Efficient cold pasteurization of tender coconut water inoculated with E. coli and Listeriamonocytogeneswas performed by circulation through a column filled with CFN-coated glass beads. Combination of curcumin coating with blue light prevented bacterial cross contamination of fresh-cut melons through plastic surfaces contaminated with E. coli or Bac. licheniformis. Furthermore, coating of strawberries with CFN reduced fruit spoilage during simulated transportation extending the shelf life by 2-3 days. Implications, both scientific and agricultural BARD Report - Project4680 Page 2 of 17 Antimicrobial food-contact nanomaterials based on natural active principles will preserve food quality and ensure safety. Understanding mode of antimicrobial action of curcumin will allow enhancing its dark efficacy, e.g. by targeting the microbial cellular adaptation mechanisms.
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Manulis-Sasson, Shulamit, Christine D. Smart, Isaac Barash, Laura Chalupowicz, Guido Sessa, and Thomas J. Burr. Clavibacter michiganensis subsp. michiganensis-tomato interactions: expression and function of virulence factors, plant defense responses and pathogen movement. United States Department of Agriculture, February 2015. http://dx.doi.org/10.32747/2015.7594405.bard.

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Clavibactermichiganensissubsp. michiganensis(Cmm), the causal agent of bacterial wilt and canker of tomato, is the most destructive bacterial disease of tomato causing substantial economic losses in Israel, the U.S.A. and worldwide. The goal of the project was to unravel the molecular strategies that allow Cmm, a Gram-positive bacterium, to develop a successful infection in tomato. The genome of Cmm contains numerous genes encoding for extracellular serine proteases and cell wall degrading enzymes. The first objective was to elucidate the role of secreted serine proteases in Cmm virulence. Mutants of nine genes encoding serine proteases of 3 different families were tested for their ability to induce wilting, when tomato stems were puncture-inoculated, as compared to blisters formation on leaves, when plants were spray-inoculated. All the mutants showed reduction in wilting and blister formation as compared to the wild type. The chpCmutant displayed the highest reduction, implicating its major role in symptom development. Five mutants of cell wall degrading enzymes and additional genes (i.e. perforin and sortase) caused wilting but were impaired in their ability to form blisters on leaves. These results suggest that Cmm differentially expressed virulence genes according to the site of penetration. Furthermore, we isolated and characterized two Cmmtranscriptional activators, Vatr1 and Vatr2 that regulate the expression of virulence factors, membrane and secreted proteins. The second objective was to determine the effect of bacterial virulence genes on movement of Cmm in tomato plants and identify the routes by which the pathogen contaminates seeds. Using a GFP-labeledCmm we could demonstrate that Cmm extensively colonizes the lumen of xylem vessels and preferentially attaches to spiral secondary wall thickening of the protoxylem and formed biofilm-like structures composed of large bacterial aggregates. Our findings suggest that virulence factors located on the chp/tomAPAI or the plasmids are required for effective movement of the pathogen in tomato and for the formation of cellular aggregates. We constructed a transposon plasmid that can be stably integrated into Cmm chromosome and express GFP, in order to follow movement to the seeds. Field strains from New York that were stably transformed with this construct, could not only access seeds systemically through the xylem, but also externally through tomato fruit lesions, which harbored high intra-and intercellular populations. Active movement and expansion of bacteria into the fruit mesocarp and nearby xylem vessels followed, once the fruit began to ripen. These results highlight the ability of Cmm to invade tomato fruit and seed through multiple entry routes. The third objective was to assess correlation between disease severity and expression levels of Cmm virulence genes and tomato defense genes. The effect of plant age on expression of tomato defense related proteins during Cmm infection was analyzed by qRT-PCR. Five genes out of eleven showed high induction at early stages of infection of plants with 19/20 leaves compared to young plants bearing 7/8 leaves. Previous results showed that Cmm virulence genes were expressed at early stages of infection in young plants compared to older plants. Results of this study suggest that Cmm virulence genes may suppress expression of tomato defense-related genes in young plants allowing effective disease development. The possibility that chpCis involved in suppression of tomato defense genes is currently under investigation by measuring the transcript level of several PR proteins, detected previously in our proteomics study. The fourth objective was to define genome location and stability of virulence genes in Cmm strains. New York isolates were compared to Israeli, Serbian, and NCPPB382 strains. The plasmid profiles of New York isolates were diverse and differed from both Israeli and Serbian strains. PCR analysis indicated that the presence of putative pathogenicity genes varied between isolates and highlighted the ephemeral nature of pathogenicity genes in field populations of Cmm. Results of this project significantly contributed to the understanding of Cmm virulence, its movement within tomato xylem or externally into the seeds, the role of serine proteases in disease development and initiated research on global regulation of Cmm virulence. These results form a basis for developing new strategies to combat wilt and canker disease of tomato.
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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova, and Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604286.bard.

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The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.
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Manulis, Shulamit, Christine D. Smart, Isaac Barash, Guido Sessa, and Harvey C. Hoch. Molecular Interactions of Clavibacter michiganensis subsp. michiganensis with Tomato. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7697113.bard.

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Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of bacterial wilt and canker of tomato, is the most destructive bacterial disease of tomato causing substantial economic losses in Israel, the U.S.A. and worldwide. The molecular strategies that allow Cmm, a Gram-positive bacterium, to develop a successful infection in tomato plants are largely unknown. The goal of the project was to elucidate the molecular interactions between Cmmand tomato. The first objective was to analyze gene expression profiles of susceptible tomato plants infected with pathogenic and endophytic Cmmstrains. Microarray analysis identified 122 genes that were differentially expressed during early stages of infection. Cmm activated typical basal defense responses in the host including induction of defense-related genes, production of scavenging of free oxygen radicals, enhanced protein turnover and hormone synthesis. Proteomic investigation of the Cmm-tomato interaction was performed with Multi-Dimensional Protein Identification Technology (MudPIT) and mass spectroscopy. A wide range of enzymes secreted by Cmm382, including cell-wall degrading enzymes and a large group of serine proteases from different families were identified in the xylem sap of infected tomato. Based on proteomic results, the expression pattern of selected bacterial virulence genes and plant defense genes were examined by qRT-PCR. Expression of the plasmid-borne cellulase (celA), serine protease (pat-1) and serine proteases residing on the chp/tomA pathogenicity island (chpCandppaA), were significantly induced within 96 hr after inoculation. Transcription of chromosomal genes involved in cell wall degradation (i.e., pelA1, celB, xysA and xysB) was also induced in early infection stages. The second objective was to identify by VIGS technology host genes affecting Cmm multiplication and appearance of disease symptoms in plant. VIGS screening showed that out of 160 tomato genes, which could be involved in defense-related signaling, suppression of 14 genes led to increase host susceptibility. Noteworthy are the genes Snakin-2 (inhibitor of Cmm growth) and extensin-like protein (ELP) involved in cell wall fortification. To further test the significance of Snakin -2 and ELP in resistance towards Cmm, transgenic tomato plants over-expressing the two genes were generated. These plants showed partial resistance to Cmm resulting in a significant delay of the wilt symptoms and reduction in size of canker lesion compared to control. Furthermore, colonization of the transgenic plants was significantly lower. The third objective was to assess the involvement of ethylene (ET), jasmonate (JA) and salicylic acid (SA) in Cmm infection. Microarray and proteomic studies showed the induction of enzymes involved in ET and JA biosynthesis. Cmm promoted ET production 8 days after inoculation and SIACO, a key enzyme of ET biosynthesis, was upregulated. Inoculation of the tomato mutants Never ripe (Nr) impaired in ET perception and transgenic plants with reduced ET synthesis significantly delayed wilt symptoms as compared to the wild-type plants. The retarded wilting in Nr plants was shown to be a specific effect of ET insensitivity and was not due to altered expression of defense related genes, reduced bacterial population or decrease in ethylene biosynthesis . In contrast, infection of various tomato mutants impaired in JA biosynthesis (e.g., def1, acx1) and JA insensitive mutant (jai1) yielded unequivocal results. The fourth objective was to determine the role of cell wall degrading enzymes produced by Cmm in xylem colonization and symptoms development. A significance increase (2 to 7 fold) in expression of cellulases (CelA, CelB), pectate lyases (PelA1, PelA2), polygalacturonase and xylanases (XylA, XylB) was detected by qRT-PCR and by proteomic analysis of the xylem sap. However, with the exception of CelA, whose inactivation led to reduced wilt symptoms, inactivation of any of the other cell wall degrading enzymes did not lead to reduced virulence. Results achieved emphasized the complexity involved in Cmm-tomato interactions. Nevertheless they provide the basis for additional research which will unravel the mechanism of Cmm pathogenicity and formulating disease control measures.
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Rahimipour, Shai, and David Donovan. Renewable, long-term, antimicrobial surface treatments through dopamine-mediated binding of peptidoglycan hydrolases. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597930.bard.

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There is a need for renewable antimicrobial surface treatments that are semi- permanent, can eradicate both biofilms and planktonic pathogens over long periods of time and that do not select for resistant strains. This proposal describes a dopamine binding technology that is inexpensive, bio-friendly, non-toxic, and uses straight-forward commercially available products. The antimicrobial agents are peptidoglycanhydrolase enzymes that are non-toxic and highly refractory to resistance development. The goal of this project is to create a treatment that will be applicable to a wide variety of surfaces and will convey long-lasting antimicrobial activity. Although the immediate goal is to create staphylolytic surfaces, the technology should be applicable to any pathogen and will thus contribute to no less than 3 BARD priorities: 1) increased animal production by protecting animals from invasive and emerging diseases, 2) Antimicrobial food packaging will improve food safety and security and 3) sustainable bio- energy systems will be supported by coating fermentation vats with antimicrobials that could protect ethanolic fermentations from Lactobacillus contamination that reduces ethanol yields. The dopamine-based modification of surfaces is inspired by the strong adhesion of mussel adhesion proteins to virtually all types of surfaces, including metals, polymers, and inorganic materials. Peptidoglycanhydrolases (PGHs) meet the criteria of a surface bound antimicrobial with their site of action being extracellular peptidoglycan (the structural basis of the bacterial cell wall) that when breached causes osmotic lysis. As a proof of principle, we will develop technology using peptidoglycanhydrolase enzymes that target Staphylococcus aureus, a notoriously contagious and antimicrobial-resistant pathogen. We will test for susceptibility of the coating to a variety of environmental stresses including UV light, abrasive cleaning and dessication. In order to avoid resistance development, we intend to use three unique, synergistic, simultaneous staphylococcal enzyme activities. The hydrolases are modular such that we have created fusion proteins with three lytic activities that are highly refractory to resistance development. It is essential to use multiple simultaneous activities to avoid selecting for antimicrobial resistant strains. This strategy is applicable to both Gram positive and negative pathogens. We anticipate that upon completion of this award the technology will be available for commercialization within the time required to achieve a suitable high volume production scheme for the required enzymes (~1-2 years). We expect the modified surface will remain antimicrobial for several days, and when necessary, the protocol for renewal of the surface will be easily applied in a diverse array of environments, from food processing plants to barnyards.
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Jorgensen, Frieda, Andre Charlett, Craig Swift, Anais Painset, and Nicolae Corcionivoschi. A survey of the levels of Campylobacter spp. contamination and prevalence of selected antimicrobial resistance determinants in fresh whole UK-produced chilled chickens at retail sale (non-major retailers). Food Standards Agency, June 2021. http://dx.doi.org/10.46756/sci.fsa.xls618.

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Campylobacter spp. are the most common bacterial cause of foodborne illness in the UK, with chicken considered to be the most important vehicle for this organism. The UK Food Standards Agency (FSA) agreed with industry to reduce Campylobacter spp. contamination in raw chicken and issued a target to reduce the prevalence of the most contaminated chickens (those with more than 1000 cfu per g chicken neck skin) to below 10 % at the end of the slaughter process, initially by 2016. To help monitor progress, a series of UK-wide surveys were undertaken to determine the levels of Campylobacter spp. on whole UK-produced, fresh chicken at retail sale in the UK. The data obtained for the first four years was reported in FSA projects FS241044 (2014/15) and FS102121 (2015 to 2018). The FSA has indicated that the retail proxy target for the percentage of highly contaminated raw whole retail chickens should be less than 7% and while continued monitoring has demonstrated a sustained decline for chickens from major retailer stores, chicken on sale in other stores have yet to meet this target. This report presents results from testing chickens from non-major retailer stores (only) in a fifth survey year from 2018 to 2019. In line with previous practise, samples were collected from stores distributed throughout the UK (in proportion to the population size of each country). Testing was performed by two laboratories - a Public Health England (PHE) laboratory or the Agri-Food & Biosciences Institute (AFBI), Belfast. Enumeration of Campylobacter spp. was performed using the ISO 10272-2 standard enumeration method applied with a detection limit of 10 colony forming units (cfu) per gram (g) of neck skin. Antimicrobial resistance (AMR) to selected antimicrobials in accordance with those advised in the EU harmonised monitoring protocol was predicted from genome sequence data in Campylobacter jejuni and Campylobacter coli isolates The percentage (10.8%) of fresh, whole chicken at retail sale in stores of smaller chains (for example, Iceland, McColl’s, Budgens, Nisa, Costcutter, One Stop), independents and butchers (collectively referred to as non-major retailer stores in this report) in the UK that are highly contaminated (at more than 1000 cfu per g) with Campylobacter spp. has decreased since the previous survey year but is still higher than that found in samples from major retailers. 8 whole fresh raw chickens from non-major retailer stores were collected from August 2018 to July 2019 (n = 1009). Campylobacter spp. were detected in 55.8% of the chicken skin samples obtained from non-major retailer shops, and 10.8% of the samples had counts above 1000 cfu per g chicken skin. Comparison among production plant approval codes showed significant differences of the percentages of chicken samples with more than 1000 cfu per g, ranging from 0% to 28.1%. The percentage of samples with more than 1000 cfu of Campylobacter spp. per g was significantly higher in the period May, June and July than in the period November to April. The percentage of highly contaminated samples was significantly higher for samples taken from larger compared to smaller chickens. There was no statistical difference in the percentage of highly contaminated samples between those obtained from chicken reared with access to range (for example, free-range and organic birds) and those reared under standard regime (for example, no access to range) but the small sample size for organic and to a lesser extent free-range chickens, may have limited the ability to detect important differences should they exist. Campylobacter species was determined for isolates from 93.4% of the positive samples. C. jejuni was isolated from the majority (72.6%) of samples while C. coli was identified in 22.1% of samples. A combination of both species was found in 5.3% of samples. C. coli was more frequently isolated from samples obtained from chicken reared with access to range in comparison to those reared as standard birds. C. jejuni was less prevalent during the summer months of June, July and August compared to the remaining months of the year. Resistance to ciprofloxacin (fluoroquinolone), erythromycin (macrolide), tetracycline, (tetracyclines), gentamicin and streptomycin (aminoglycosides) was predicted from WGS data by the detection of known antimicrobial resistance determinants. Resistance to ciprofloxacin was detected in 185 (51.7%) isolates of C. jejuni and 49 (42.1%) isolates of C. coli; while 220 (61.1%) isolates of C. jejuni and 73 (62.9%) isolates of C. coli isolates were resistant to tetracycline. Three C. coli (2.6%) but none of the C. jejuni isolates harboured 23S mutations predicting reduced susceptibility to erythromycin. Multidrug resistance (MDR), defined as harbouring genetic determinants for resistance to at least three unrelated antimicrobial classes, was found in 10 (8.6%) C. coli isolates but not in any C. jejuni isolates. Co-resistance to ciprofloxacin and erythromycin was predicted in 1.7% of C. coli isolates. 9 Overall, the percentages of isolates with genetic AMR determinants found in this study were similar to those reported in the previous survey year (August 2016 to July 2017) where testing was based on phenotypic break-point testing. Multi-drug resistance was similar to that found in the previous survey years. It is recommended that trends in AMR in Campylobacter spp. isolates from retail chickens continue to be monitored to realise any increasing resistance of concern, particulary to erythromycin (macrolide). Considering that the percentage of fresh, whole chicken from non-major retailer stores in the UK that are highly contaminated (at more than 1000 cfu per g) with Campylobacter spp. continues to be above that in samples from major retailers more action including consideration of interventions such as improved biosecurity and slaughterhouse measures is needed to achieve better control of Campylobacter spp. for this section of the industry. The FSA has indicated that the retail proxy target for the percentage of highly contaminated retail chickens should be less than 7% and while continued monitoring has demonstrated a sustained decline for chickens from major retailer stores, chicken on sale in other stores have yet to meet this target.
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