Observations on the Nutrition of Bacteroides Succinogenes—A Ruminal Cellulolytic Bacterium

Abstract

Summary Studies on five strains of Bacteroides succinogenes , including one recent isolate, indicated that biotin was essential for growth of four strains and highly stimulatory for the other. p -Aminobenzoic acid stimulated the growth of two strains. No other vitamins had an effect on growth. Ammonia was essential for growth even in the presence of 19 amino acids, a mixture of purines and pyrimidines, and all B vitamins. None of the amino acids were essential for growth, and good, but somewhat delayed, growth was obtained when cysteine or glutathione was the only source of amino acids available. Studies on Strain S85 indicated that cysteine or sulfide could serve as the sole source of sulfur. The sulfur requirement was not adequately studied, as the only reducing agents found that allowed good growth in chemically defined media were those that also served as a sulfur source. The essentiality of PO 4 −−− , NH 4 + , Mg ++ , Ca ++ , K + , and Na + was demonstrated and the levels required were established for Strain S85. Although glucose was used as an energy source in most experimental media, it was demonstrated that good growth and cellulose digestion occurred in a medium containing only cellulose, p -aminobenzoic acid, biotin, cysteine, alanine, phenylalanine, valerate, isobutyrate, a carbonic acid-bicarbonate buffer, resazurin, and minerals. The results indicate the relatively great ability of B. succinogenes to synthesize cellular constituents and, also, how well this bacterium is adapted to the environment of the rumen.