CHANGES WITH GROWTH-RATE IN THE MEMBRANE LIPID-COMPOSITION OF AND AMINO-ACID UTILIZATION BY CONTINUOUS CULTURES OF CAMPYLOBACTER-JEJUNI

Methods and media (defined and complex) are described which permit stu dies designed to determine the influence of single environmental facto rs on the survival and virulence of Campylobacter jejuni. The effect o f growth rate on selected physiological traits (amino acid utilization , membrane lipid composition, motility, cell morphology) was studied i n continuous culture. In both media, growth was at the expense of amin o acid (serine, aspartate, glutamate and proline) catabolism. Slow gro wth in the complex medium shifted amino acid utilization from more (se rine and aspartate) to less preferred substrates (glutamate, proline a nd possibly amino acids from the proteolysis of peptones). Low growth rates promoted the conversion of unsaturated 11-octadecenoic acid subs tituted phosphatidyl ethanolamines to corresponding 11-methylene subst ituted species, a feature correlated with stationary phase and exposur e to environmental stress in other organisms. During continuous growth , cells lost motility although they still possessed flagella. Slow gro wth resulted in longer cells. Future studies will investigate the inde pendent effects of nutrient stress and growth rate on the virulence an d persistence of cells.