Abstract
is a Gram-negative organism, strongly associated with aggressive forms of periodontitis. An important virulence property of is its ability to form tenacious biofilms that can attach to abiotic as well as biotic surfaces. The histone-like (H-NS) family of nucleoid-structuring proteins act as transcriptional silencers in many Gram-negative bacteria. To evaluate the role of H-NS in , mutant derivatives of serotype a strain D7S were generated. Characteristics of the mutant phenotype included shorter and fewer pili, and substantially lower monospecies biofilm formation relative to the wild type. Furthermore, the D7S mutant exhibited significantly reduced growth within a seven-species oral biofilm model. However, no apparent difference was observed regarding the numbers and proportions of the remaining six species regardless of being co-cultivated with D7S or its parental strain. Proteomics analysis of the strains grown in monocultures confirmed the role of H-NS as a repressor of gene expression in . Interestingly, proteomics analysis of the multispecies biofilms indicated that the wild type and mutant imposed different regulatory effects on the pattern of protein expression in the other species, i.e., mainly spp., , and . Gene ontology analysis revealed that a large portion of the differentially regulated proteins was related to translational activity. Taken together, our data suggest that, apart from being a negative regulator of protein expression in , H-NS promotes biofilm formation and may be an important factor for survival of this species within a multispecies biofilm.
Bao, Kai