Nutrition of Coryneform Bacteria from Milk and Dairy Sources

S ummary . Growth requirements were determined for 112 cultures of coryneform bacteria including strains of Corynebacterium bovis, C. ulcerans and C. lacticum ; in general they were quite distinctive. Of 42 C. bovis strains all had an unsaturated fatty acid requirement fulfilled in chemically defined media by Tween 80, and, but for an atypically nonureolytic strain, all utilized ammonia and urea nitrogen. Whereas vitamins were unessential for the majority of C. bovis. 18 strains failed to grow in the absence of nicotinic acid; however, for 11 of these Casamino Acids replaced nicotinic acid in supporting growth. Thirteen C. ulcerans strains from aseptically drawn milk, as well as two Type Culture strains (NCTC 7907 and 7908) from the human throat required amino acid nitrogen sources, nicotinic acid, pantothenate and biotin. Some nutritional heterogeneity was shown by 46 strains collectively described as C. lacticum obtained from market milk, milk products and dairy utensils; nevertheless the nutritional differences between the groups of these strains correlated broadly with other distinguishing properties. A group of 9 markedly caseolytic strains required amino acid nitrogen sources, thiamine and biotin, whereas a second group of 30 strains, some utilizing inorganic nitrogen sources, required thiamine and pantothenate, with or without biotin. The remaining C. lacticum strains together with a number of unidentified strains from similar sources were generally slow growing and had widely differing growth requirements.