
Full text loading...
Category: Environmental Microbiology
Adaptive Responses of Vibrios, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815714/9781555813659_Chap10-1.gif /docserver/preview/fulltext/10.1128/9781555815714/9781555813659_Chap10-2.gifAbstract:
This chapter discusses several aspects of adaptation that have been suggested to play a role in the survival of vibrios, in particular, starvation adaptation, the viable but nonculturable (VBNC) response, and biofilm formation. In addition, it talks about quorum sensing, which has been shown to control many phenotypes associated with survival under different conditions. The potential role for oxidative stress in the VBNC response is discussed. Bacteria have evolved complex mechanisms to deal with conditions that are routinely encountered in the natural environment. Such adaptive responses are characterized by changes in gene expression, physiology, and morphology. The potential for nonculturable cells to resuscitate, irrespective of whether the VBNC state is truly a protective strategy or is simply a consequence of stress leading to death, does have implications for the survival of vibrios in the natural environment. A section presents some of the current theories on factors driving the generation and resuscitation of nonculturable cells. The regulation of biofilm formation is complex, involving a range of physical and biological factors, the influences of which vary between species. The chapter provides a review of biofilm formation by Vibrio spp., with a strong emphasis on Vibrio cholerae, for which the most data are available. Biofilm formation on biotic surfaces has implications for the outbreak of disease.
Full text loading...
Model for the entry into and exit from carbon starvation in Vibrio S14 (shaded rod and coccoid forms). Ovals represent regulators (i.e., RelA, SpoT, RpoE, RpoS). Rectangles denote signaling molecules (i.e., ppGpp, quorum-sensing auto-inducer molecules). Dotted lines refer to postulated regulators and pathways. Large shaded ovals depict Sti and Iup protein re-sponders. Overlap between Sti ovals indicates protein responders, which are induced by both SpoT and RelA. One hundred fifty-seven Stis and 18 Iups have been mapped by 2D-PAGE, and their respective rates of synthesis and modes of regulation have been characterized. mRNA (~~~) modification and stability during starvation are proposed to be modulated by RNase E (large oval), mRNA-binding protein(s) (small hatched oval), and polyadenylation (polyA tail). Triangles and circles on the bacterial cells represent low-and high-affinity uptake for glucose and amino acids, respectively.
V. cholerae QS systems. Three systems regulate biofilm formation, virulence, and HA/protease production. Details of the signal transduction pathways are in the text.
Confocal laser scanning microscope images of biofilms of V. cholerae strains under nongrazed (top of each panel) and grazed (bottom of each panel) treatments. Biofilms were stained with Live/Dead viability probe, and images were taken using a confocal laser scanning microscope. Magnification, ×200. Scale bar, 50 μm.
Quorum-sensing homologues in Vibrio spp.; system components are grouped together