Mutation in flrA and mshA Genes of Vibrio cholerae Inversely Involved in vps-Independent Biofilm Driving Bacterium Toward Nutrients in Lake Water

Frontiers in Microbiology

Afsar Ali¹  Shrestha Sinha-Ray² 

[1] Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, GainesvilleFL, United States;Department of Microbiology and Cell Science, College of Agricultural and Life Sciences, University of Florida, GainesvilleFL, United States;Emerging Pathogens Institute, University of Florida, GainesvilleFL, United States;

关键词: Vibrio cholerae;    biofilm;    motility;    nutrient-poor;    microcosm;    chemotaxis;   

DOI  :  10.3389/fmicb.2017.01770

来源: DOAJ

【 摘 要 】

Many bacterial pathogens promote biofilms that confer resistance against stressful survival conditions. Likewise Vibrio cholerae O1, the causative agent of cholera, and ubiquitous in aquatic environments, produces vps-dependent biofilm conferring resistance to environmental stressors and predators. Here we show that a 49-bp deletion mutation in the flrA gene of V. cholerae N16961S strain resulted in promotion of vps-independent biofilm in filter sterilized lake water (FSLW), but not in nutrient-rich L-broth. Complementation of flrA mutant with the wild-type flrA gene inhibited vps-independent biofilm formation. Our data demonstrate that mutation in the flrA gene positively contributed to vps-independent biofilm production in FSLW. Furthermore, inactivation of mshA gene, encoding the main pilin of mannose sensitive hemagglutinin (MSHA pilus) in the background of a ΔflrA mutant, inhibited vps-independent biofilm formation. Complementation of ΔflrAΔmshA double mutant with wild-type mshA gene restored biofilm formation, suggesting that mshA mutation inhibited ΔflrA-driven biofilm. Taken together, our data suggest that V. cholerae flrA and mshA act inversely in promoting vps-independent biofilm formation in FSLW. Using a standard chemotactic assay, we demonstrated that vps-independent biofilm of V. cholerae, in contrast to vps-dependent biofilm, promoted bacterial movement toward chitin and phosphate in FSLW. A ΔflrAΔmshA double mutant inhibited the bacterium from moving toward nutrients; this phenomenon was reversed with reverted mutants (complemented with wild-type mshA gene). Movement to nutrients was blocked by mutation in a key chemotaxis gene, cheY-3, although, cheY-3 had no effect on vps-independent biofilm. We propose that in fresh water reservoirs, V. cholerae, on repression of flagella, enhances vps-independent biofilm that aids the bacterium in acquiring nutrients, including chitin and phosphate; by doing so, the microorganism enhances its ability to persist under nutrient-limited conditions.

【 授权许可】

Unknown