1887

Abstract

Many species of bacteria can adhere to surfaces and grow as sessile communities. The continued accumulation of bacteria can eventually lead to the extremely high-cell-density environment characteristic of many biofilms or cell colonies. This is the normal habitat of the cariogenic species which normally resides in the high-cell-density, multispecies community commonly referred to as dental plaque. Previous work has demonstrated that the transcription of two separate bacteriocins can be activated by the high-cell-density conditions created through the centrifugation and incubation of cell pellets. In this study, we identified an uncharacterized two-gene operon that was induced >10-fold by conditions of high cell density. The genes of the operon encode a putative transcription regulator and a membrane protein, which were renamed as and , respectively. A transcription fusion to the operon confirmed its induction by high cell density. Mutation of abolished bacteriocin production, greatly increased natural competence, reduced the growth rate, and severely affected biofilm formation. Interestingly, no obvious phenotypes were observed from a non-polar mutation of or mutations affecting the entire operon. These data suggest that the operon may constitute a novel regulatory system responsible for mediating a cellular response to a high-cell-density environment.

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2007-08-01
2019-10-21
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