Physiological changes in Campylobacter jejuni on entry into stationary phase.

Campylobacter jejuni NCTC 11168 does not exhibit the general increase in cellular stress resistance on entry into stationary phase that is seen in most other bacteria. This is consistent with the lack of global stationary phase regulatory elements in this organism, deduced from an analysis of its genome sequence. We now show that C. jejuni NCTC 11168 does undergo certain changes in stationary phase, of a pattern not previously described. As cells entered stationary phase there was a change in membrane fatty acid composition, principally a decrease in the proportion of unsaturated fatty acids and an increase in the content of cyclopropane and short-chain fatty acids. These changes in membrane composition were accompanied by an increase in the resilience of the cell membrane towards loss of integrity caused by pressure and an increase in cellular pressure resistance. By contrast, there were no major changes in resistance to acid or heat treatment. A similar pattern of changes in stress resistance on entry into stationary phase was seen in C. jejuni NCTC 11351, the type strain. These changes appear to represent a restricted physiological response to the conditions existing in stationary phase cultures, in an organism having limited capacity for genetic regulation and adaptation to environment.