Sinha-Ray Shrestha, Ali Afsar
Emerging Pathogens Institute, University of Florida, GainesvilleFL, United States.
Department of Microbiology and Cell Science, College of Agricultural and Life Sciences, University of Florida, GainesvilleFL, United States.
Front Microbiol. 2017 Sep 13;8:1770. doi: 10.3389/fmicb.2017.01770. eCollection 2017.
Many bacterial pathogens promote biofilms that confer resistance against stressful survival conditions. Likewise O1, the causative agent of cholera, and ubiquitous in aquatic environments, produces -dependent biofilm conferring resistance to environmental stressors and predators. Here we show that a 49-bp deletion mutation in the gene of N16961S strain resulted in promotion of independent biofilm in filter sterilized lake water (FSLW), but not in nutrient-rich L-broth. Complementation of mutant with the wild-type gene inhibited -independent biofilm formation. Our data demonstrate that mutation in the gene positively contributed to -independent biofilm production in FSLW. Furthermore, inactivation of gene, encoding the main pilin of mannose sensitive hemagglutinin (MSHA pilus) in the background of a Δ mutant, inhibited independent biofilm formation. Complementation of ΔΔ double mutant with wild-type gene restored biofilm formation, suggesting that mutation inhibited Δ-driven biofilm. Taken together, our data suggest that and act inversely in promoting -independent biofilm formation in FSLW. Using a standard chemotactic assay, we demonstrated that -independent biofilm of , in contrast to -dependent biofilm, promoted bacterial movement toward chitin and phosphate in FSLW. A ΔΔ double mutant inhibited the bacterium from moving toward nutrients; this phenomenon was reversed with reverted mutants (complemented with wild-type gene). Movement to nutrients was blocked by mutation in a key chemotaxis gene, -3, although, -3 had no effect on -independent biofilm. We propose that in fresh water reservoirs, , on repression of flagella, enhances -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.
许多细菌病原体可促进生物膜形成，从而赋予其抵抗恶劣生存条件的能力。同样，霍乱病原体O1在水生环境中广泛存在，它可产生依赖于 的生物膜，从而抵抗环境应激源和捕食者。在此，我们发现N16961S菌株 基因中的一个49碱基对缺失突变导致其在经滤膜除菌的湖水中（FSLW）促进了非依赖型生物膜的形成，但在营养丰富的L肉汤中却未出现这种情况。用野生型 基因对 突变体进行互补抑制了非依赖型生物膜的形成。我们的数据表明， 基因中的突变正向促进了FSLW中非依赖型生物膜的产生。此外，在Δ 突变体背景下，编码甘露糖敏感血凝素主要菌毛蛋白（MSHA菌毛）的 基因失活，抑制了非依赖型生物膜的形成。用野生型 基因对ΔΔ双突变体进行互补可恢复生物膜的形成，这表明 突变抑制了Δ驱动的生物膜形成。综上所述，我们的数据表明， 在促进FSLW中非依赖型生物膜形成方面起相反作用。通过标准趋化分析，我们证明，与依赖型生物膜相比， 的非依赖型生物膜促进了细菌在FSLW中向几丁质和磷酸盐的移动。ΔΔ双突变体抑制了细菌向营养物质的移动；这种现象在回复突变体（用野生型 基因互补）中得到了逆转。关键趋化基因-3中的突变阻断了向营养物质的移动，尽管-3对非依赖型生物膜没有影响。我们提出，在淡水水库中， 通过抑制鞭毛，增强了非依赖型生物膜，这有助于细菌获取包括几丁质和磷酸盐在内的营养物质；通过这样做，微生物增强了其在营养有限条件下持续生存的能力。
