Vitamin Requirements of Microbacterium lacticum Orla-Jensen

Abstract

D-Ca pantothenate is an essential nutritional requirement for some strains of M. lacticum. Thiamine also exerted a stimulatory effect on growth. A basal medium was prepared which supported growth of most strains. The inoculum for the basal medium was made by growing 5 ml. of a 4-day culture in yeast-extract-proteose-peptone-glucose broth. This was centrifuged and the sedimented cells washed with 5 ml. of 0.85% saline. One loop of this suspension served as the inoculum for 10 ml. of basal medium. Ten of 14 strains of M. lacticum could grow on repeated subculture in the medium. Observations showed that d-Ca pantothenate was essential for the initiation of growth but thiamine was not. The 10 strains which grew in the basal medium also grew, though poorly, when thiamine was omitted. The minimal amt. of d-Ca pantothenate needed to start growth in most strains was about 0.02 x/ml., and the maximum effect was obtained at 0.1 x/ml. The response to thiamine was not linear in cones, of 0.01-1.0 x/ml.