Vitamin Requirements of Several Cellulolytic Rumen Bacteria

Abstract

Scott , H. W. (Ohio Agricultural Experiment Station, Wooster), and B. A. Dehority . Vitamin requirements of several cellulolytic rumen bacteria. J. Bacteriol. 89: 1169–1175. 1965.—Four strains of cellulolytic bacteria recently isolated from in vitro rumen fermentations were used in this study. Nine water-soluble vitamins were tested in single-deletion and single-addition plus biotin experiments, each with and without charcoal-extracted casein hydrolysate. Bacteroides succinogenes A3C and B21a required only biotin under the above experimental conditions. Ruminococcus flavefaciens B34b showed an absolute requirement for biotin and was stimulated by p -aminobenzoic acid (PABA) in the single-deletion experiments. In the single-addition plus biotin experiments, PABA and, to a lesser extent, vitamin B 12 appeared to be required for maximal growth. The presence or absence of casein hydrolysate did not affect the vitamin requirements for the aforementioned three strains. In the single-deletion experiments, R. flavefaciens Cla showed an absolute requirement for biotin and, when casein hydrolysate was omitted, for B 12 . When casein hydrolysate was present, no requirement for B 12 could be observed. In the single-addition experiments where the basal medium contained biotin and casein hydrolysate or B 12 , PABA was required for maximal growth; however, the single deletion of PABA caused only slight retardation of growth. Investigation of the B 12 or casein hydrolysate requirement of Cla revealed that a mixture of purified amino acids simulating casein hydrolysate satisfied this requirement. Subsequent work indicated that this requirement could be satisfied by the amino acid methionine.