MCLMAN, a new minimal medium for Campylobacter jejuni NCTC 11168

The design of a defined synthetic minimal medium for Campylobacter jejuni strain NCTC 11168 that includes only inorganic salts and necessary amino acids and vitamins is useful in physiological assays and responses to exogeneous agents. In silico genomic analysis of biosynthesis pathways was preliminarily performed prior to experimental assays to determine (i) amino acids and vitamins necessary for improving the growth of C. jejuni strains, and (ii) the most appropriate sources of carbon, nitrogen and sulfur. The different sources of carbon, nitrogen and sulfur were analyzed by comparing growth parameters. A new minimal medium that contains inorganic salts, the amino acids l-cysteine, l-leucine, l-methionine and l-aspartic acid (nitrogen source), the vitamin niacinamide and lactate as a carbon source, named MCLMAN (medium cysteine leucine methionine aspartic acid niacinamide), was checked on some C. jejuni strains and showed similar growth ratios and final biomass when compared to the most frequently used medium, MEM (modified Eagle's medium), primarily designed for eukaryote cell culture and more complex than MCLMAN. Our results show that C. jejuni presents auxotrophy for cysteine and methionine and can be inhibited by ammonium sulfate. A simple minimal medium containing few amino acids and vitamins will facilitate physiological studies of different functions in C. jejuni strains submitted to different stresses.