Survival of Campylobacter jejuni during stationary phase: Evidence for theabsence of a phenotypic stationary-phase response

When Campylobacter jejuni NCTC 11351 was grown microaerobically in rich med ium at 39 degreesC, entry into stationary phase was followed by a rapid dec line in viable numbers to leave a residual population of 1% of the maximum number or Less. Loss of viability was preceded by sublethal injury which wa s seen as a loss of the ability to grow on media containing 0.1% sodium deo xycholate or 1% sodium chloride. Resistance of cells to mild heat stress (5 0 degreesC) or aeration was greatest in exponential phase and declined duri ng early stationary phase. These results show that C. jejuni does not mount the normal phenotypic stationary-phase response which results in enhanced stress resistance. This conclusion is consistent dth the absence of rpoS ho mologues in the recently reported genome sequence of this species and their probable absence from strain NCTC 11351. During prolonged incubation of C. jejuni NCTC 11351 in stationary phase, an unusual pattern of decreasing an d increasing heat resistance was observed that coincided with fluctuations in the viable count. During stationary phase of Campylobacter coli UA585, n onmotile variants and those with impaired ability to form coccoid cells wer e isolated at high frequency, Taken together, these observations suggest th at stationary-phase cultures of campylobacters are dynamic populations and that this ma be a strategy to promote survival in at least some strains. In vestigation of two spontaneously arising variants (NM3 and SC4) of C. coli UA585 showed that a reduced ability to form coccoid cells did not affect su rvival under nongrowth conditions.