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Chapter 32 : Survival Strategies of Campylobacter jejuni: Stress Responses, the Viable but Nonculturable State, and Biofilms
Category: Bacterial Pathogenesis
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Survival Strategies of Campylobacter jejuni: Stress Responses, the Viable but Nonculturable State, and Biofilms, Page 1 of 2< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815554/9781555814373_Chap32-1.gif /docserver/preview/fulltext/10.1128/9781555815554/9781555814373_Chap32-2.gif
This chapter is divided into three sections. The first covers specific stresses and responses, is organized by the type of stress encountered, and discusses specific gene products or global response pathways that participate in countering the stress condition. The second and third sections cover two different types of pleiotropic whole-population differentiation strategies or outcomes: the viable but nonculturable (VBNC) and coccoid forms of Campylobacter, and Campylobacter jejuni biofilms. Also incorporated into the latter two sections are the types of stresses that induce the differentiation, the genes involved in their formation, and the effect of differentiation on survivability or growth of C. jejuni. To date, only two regulatory factors directly affecting heat stress have been characterized, one of which is the RacR (reduced ability to colonize) response regulator. As such, nonculturable cells can be classified as both viable and nonviable, and not necessarily specifically correlated with shape. The majority of research to date on the contribution of biofilms to stress tolerance in C. jejuni has been in the context of survival in aquatic environments. It is important to point out that although this chapter specifically reviewed survival strategies and stress responses, many of the genes and pathways discussed affect multiple or all aspects of the pathogenesis cycle, encompassing colonization, transmission, and virulence.
Key Concept Ranking
- Two-Component Signal Transduction Systems
Biofilms of Campylobacter jejuni 81-176 wild-type and isogenic mutants. (A) Static biofilms grown on borosilicate glass were stained with crystal violet and visualized macroscopically (insets) or were processed for scanning electron microscopy (large photographs; bars = 10 μm). The ΔspoT mutant forms more mature biofilms than wild type; conversely, dim mutants are defective for biofilm formation. In these strains, biofilm levels correlate with levels of a calcofluor white–reactive exopolysaccharide (EPS), which is overproduced in ΔspoT and underproduced in the dim mutants ( McLennan et al., 2007 ). (B) Crystal violet–stained biofilms were visualized macroscopically (insets) or by light microscopy (large photographs; magnification, ×10 and ×100). The Δcj1226c mutant exhibits an extreme hyperbiofilm phenotype but displays wild-type levels of the CFW-reactive EPS (S. L. Svensson and E. C. Gaynor, unpublished data), suggesting multiple means by which biofilm formation can be upregulated in C. jejuni.
Characterized and putative stress response genes in C. jejuni