A Defined Medium for the Growth of the Thermophilic

SUMMARY: Biotin and methionine are essential growth factors for the aerobic thermophilic actinomycete Micromnospora vulgaris. Biotin can be partially replaced by Tween 80 (sorbitan mono-oleate). No aerial growth is obtained in the absence of methionine. A chemically defined medium containing mineral salts, phosphate buffer (pH 64), soluble starch, a mixture of 18 synthetic amino acids (including methionine) and biotin will support growth of the organism. Throughout the studies of Erikson (1952,1958), Erikson & Webley (1953) and Webley (1954) on the aerobic thermophilic actinomycete Mimmorcospora vulgaris it was found necessary to use in the main a complex medium (C.P.S.) for growth. Erikson (1952) did, however, show that the organism would grow in the presence of Czapek's mineral salt solution containing 1 yo (wlv) soluble starch, 1 yo (wlv) vitamin-free acid hydrolysate of casein and 0.01 yo (w/v) autolysed yeast extract. The present work deals with the essential growth factor requirements of the organism and the establishment of a chemically defined medium for growth