Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 9/15/2005
Publication Date: 12/1/2005
Citation: Russell, J.B., Houlihan, A.J., Rose, J.E., Angert, E.R. 2005. Bacteriocins of gram-positive bacteria and their application in biotechnology. In: Pandalai, S.G., editor. Recent Research Developments in Applied Biotechnology. Kerala, India. Research Signpost. 2:87-101.
Technical Abstract: Many Gram-positive bacteria produce small peptides (bacteriocins) that have antimicrobial activity. Some bacteriocins have a broad spectrum, but many are highly selective and can only inhibit closely related species or strains. Bacteriocin specificity is not well understood, but specific receptors may play a role in their binding to cells. Immunity proteins that sequester the bacteriocins from the cell membrane or expel them protect the bacteriocin-producing bacteria. Bacteriocin-sensitive bacteria can become resistant, but this characteristic is distinctly different from immunity. Disruption of any of the steps leading to activity (binding, insertion, and poration) could theoretically generate resistant cells, but binding is the most well understood mechanism of resistance. Most bacteriocins are positively charged, and resistant cells alter their lipoteichoic acids, become more positively charged and repel bacteriocins. Bacteriocins can be hydrolyzed by peptidases, but this degradation is at least partially inhibited by post-translational modifications that create mono-sulfide ether rings. Phylogenetic comparisons indicated that the structural genes have considerable diversity and appear to have had a different pathway of evolution than the immunity proteins. Only one bacteriocin (nisin from Lactococcus lactis) has been used commercially, but it has had a variety of applications (food safety and preservation, animal growth promotion, industrial fermentations and human disease treatment). Because resistance has stymied nisin use, researchers have screened a variety of bacteriocins to see if better ones that remain active for longer periods of time can be found.