Gram bacteria bacteriocins

Rgure 5.1. Classification scheme of the bacteriocins of Gram (+) bacteria, revised from Cotter et al. (2005b). The main distinction is made between the Class I lantibiotics, which undergo extensive post-translational modifications, and the Class II non-modified bacteriocins. The amino acid sequence and structural features of one example bacteriocin of each different class are shown. 

In addition, the antibiotics and other bacteriocins were originally detected in lactic acid bacteria, but were later also found in other Gram-positive microorganisms [28]. Lactic acid bacteria are a group of non-spore-forming, anaerobic fermentative bacteria within the Gram-positives with low GC content. 

Most antimicrobial peptides produced by Gram-positive bacteria are classified as bacteriocins, and like microcins they are diverse in size and structure.35 36 Recent classification schemes divide bacteriocins into three classes lantibiotics (class I), heat-stable non-lantibiotics (class II) and heat-labile antimicrobial proteins (class III), of which the majority of bacteriocins belong either to class I or class II. NMR spectroscopy has been applied in numerous studies of bacteriocins and an overview of the range of diversity in the 3D structures that have been determined by NMR spectroscopy is provided in Figure 4. 

Nisin is an antibacterial polypeptide produced by some strains of Lactococcus lactis. Nisin-like substances are widely produced by lactic acid bacteria. These inhibitory substances are known as bacteriocins. Nisin has been called an antibiotic, but this term is avoided because nisin is not used for therapeutic purposes in humans or animals. Nisin-producing organisms occur naturally in milk. Nisin can be used as a processing aid against gram-positive organisms. Because its effectiveness decreases as the bacterial load increases, it is unlikely to be used to cover up unhygienic practices. 

Tagg JR, Dajani AS, Wannamaker LW (1976) Bacteriocins of Gram-positive bacteria. Bacteriol Rev 40 722 - 756... 

Jack RW, Tagg JR, Ray B (1995) Bacteriocins of Gram-positive bacteria. Microbiol Rev 59 171-200... 

Havarstein LS, Holo H, Nes IF (1994) The leader peptide of colicin V shares consensus sequences with leader peptides that are common among peptide bacteriocins produced by gram positive bacteria. Microbiology 140 2383-2389... 

In the wider sense, protein toxins localized in the cytoplasm of Gram-negative bacteria are also designated as E., for example, toxins of Vibrio cholerae ( cholera toxin), the bacteriocins (e. g colicins) or the polypeptides y-E. formed by Bacillus thuringiensis which represent up to 30% of the cell weight and are used in plant protection as antifeedants against insect pests. 

Enterococcus mundtii ST4V isolated from soya beans produces a broad-spectrum bacteriocin active against Gram-positive and Gram-negative bacteria and has antiviral activity (Todorov et al., 2009). The aim of the study of Todorov et al. (2009)... 

Tagg, J. R., Dajani, A. S., Wannamaker, L. W. (1976). Bacteriocins of gram-positive bacteria. Bacteriological Reviews, 40, 722-756. 

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