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Bacteria

About: Bacteria is a research topic. Over the lifetime, 23676 publications have been published within this topic receiving 715990 citations. The topic is also known as: eubacteria.


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Journal ArticleDOI
TL;DR: Meat lactobacilli might be reservoir organisms for acquired resistance genes that can be spread to other lactic acid bacteria, and the magnitude of transfer along the food chain merits further research.
Abstract: The ability of 14 Lactobacillus strains, isolated from fermented dry sausages, to transfer tetracycline resistance encoded by tet(M) through conjugation was examined using filter mating experiments. Seven out of 14 tetracycline-resistant Lactobacillus isolates were able to transfer in vitro this resistance to Enterococcus faecalis at frequencies ranging from 10−4 to 10−6 transconjugants per recipient. Two of these strains could also transfer their resistance to Lactococcus lactis subsp. lactis, whereas no conjugal transfer to a Staphylococcus aureus recipient was found. These data suggest that meat lactobacilli might be reservoir organisms for acquired resistance genes that can be spread to other lactic acid bacteria. In order to assess the risk of this potential hazard, the magnitude of transfer along the food chain merits further research.

169 citations

Journal ArticleDOI
TL;DR: This review article is mainly focused on the ecology, biosynthesis, genetics, target sites, and applications of bacteriocins and EPS from LAB strains, and discusses about the production and functions of nutritive essential element folate and iron chelating agent such as siderophores from L AB.
Abstract: During the past two decades probiotic bacteria have been increasingly proposed as health promoting bacteria in variety of food system, because of its safety, functional, and technological characteristics. Commonly, Lactobacillus spp., Bifidobacterium spp., Saccharomyces boulardii, and some other microorganisms have been considered as probiotic strains. Possibly these bacterial strains exerted several beneficial effects into gastrointestinal tract of host while administered with variety of food system. Lactic acid bacteria (LAB) usually produce antimicrobial substances like bacteriocin which have broad spectrum of antagonist effect against closely related Gram positive and Gram negative pathogens. LAB strains often produce polymeric substances such as exopolysaccharides (EPS) which increase the colonization of probiotic bacteria by cell-cell interactions in gastrointestinal tract. LAB also produces biosurfactant which showed that the wide range of antimicrobial activity against bacterial pathogen as well as its antiadhesive properties reduces the adhesion of pathogens into gastric wall membrane. Furthermore, LAB strains have also been reported for production of antioxidants which are ability to scavenge the free radicals such as superoxide anions and hydroxyl radicals. For this sense, this review article is mainly focused on the ecology, biosynthesis, genetics, target sites, and applications of bacteriocins and EPS from LAB strains. Moreover, this review discusses about the production and functions of nutritive essential element folate and iron chelating agent such as siderophores from LAB.

169 citations

Journal ArticleDOI
TL;DR: The results established that prophenoloxidase activation is an integral component of the insect defense system involving a multitude of enzymes, which immobilizes and kills invading microorganisms.

169 citations

Journal ArticleDOI
TL;DR: Specific features of protease secretion pathways and the mechanisms of prote enzyme activation are discussed with particular reference to some of the best‐characterized extracellular proteases produced by Gram‐positive and Gram‐negative bacteria.
Abstract: Summary Many different bacteria secrete proteases into the culture medium. Extracellular proteases produced by Gram-positive bacteria are secreted by a signal-peptide-dependent pathway and have a propeptide located between the signal peptide and the mature protein. Many extracellular proteases synthesized by Gram-negative bacteria are also produced as precursors with a signal peptide. However, at least two species of Gram-negative bacteria secrete one or more proteases via a novel signal-peptide-independent route. Most proteases secreted by Gram-negative bacteria also have a propeptide whose length and location vary according to the protease. Specific features of protease secretion pathways and the mechanisms of protease activation are discussed with particular reference to some of the best-characterized extracellular proteases produced by Gram-positive and Gram-negative bacteria.

169 citations

Journal ArticleDOI
TL;DR: The results clearly demonstrated that the coexisting heterotrophic bacteria efficiently degraded and utilized dead biomass and metabolites of nitrifying bacteria, which consequently prevented accumulation of organic waste products in the biofilm.
Abstract: The cross-feeding of microbial products derived from 14C-labeled nitrifying bacteria to heterotrophic bacteria coexisting in an autotrophic nitrifying biofilm was quantitatively analyzed by using microautoradiography combined with fluorescence in situ hybridization (MAR-FISH). After only nitrifying bacteria were labeled with [14C]bicarbonate, biofilm samples were incubated with and without NH4+ as a sole energy source for 10 days. The transfer of 14C originally incorporated into nitrifying bacterial cells to heterotrophic bacteria was monitored with time by using MAR-FISH. The MAR-FISH analysis revealed that most phylogenetic groups of heterotrophic bacteria except the beta-Proteobacteria showed significant uptake of 14C-labeled microbial products. In particular, the members of the Chloroflexi were strongly MAR positive in the culture without NH4+ addition, in which nitrifying bacteria tended to decay. This indicated that the members of the Chloroflexi preferentially utilized microbial products derived from mainly biomass decay. On the other hand, the members of the Cytophaga-Flavobacterium cluster gradually utilized 14C-labeled products in the culture with NH4+ addition in which nitrifying bacteria grew. This result suggested that these bacteria preferentially utilized substrate utilization-associated products of nitrifying bacteria and/or secondary metabolites of 14C-labeled structural cell components. Our results clearly demonstrated that the coexisting heterotrophic bacteria efficiently degraded and utilized dead biomass and metabolites of nitrifying bacteria, which consequently prevented accumulation of organic waste products in the biofilm.

168 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20235,286
202210,729
20211,047
20201,096
20191,044