Utilization of sulfur compounds by Streptococcus bovis.

Prescott, J. M. (A. &. M. College of Texas, College Station). Utilization of sulfur compounds by Streptococcus bovis. J. Bacteriol. 82:724-728. 1961.-Two strains of Streptococcus bovis utilize a variety of compounds as their only source of sulfur, yet exert a definite selectivity in their nutritional requirements for this element. Among sulfur-containing amino acids and related compounds, cystine and cysteine support excellent growth, but cysteic acid and cysteine sulfinic acid do not; methionine is completely inactive as an only sulfur source, but growth is provided by lanthionine, djenkolic acid, allo-cystathionine, homocystine, homocysteine, and glutathione. Several organic sulfur compounds other than amino acids are effective sulfur sources, among which are thioglycolate, thiomalate, thiourea, and thiouracil. In contrast, thiodiglycolate, thiodiglycol, and (phenylthio) acetic acid fail to support growth. Of the inorganic sulfur sources tested, sulfide and thiosulfate are utilized, but sulfite and sulfate are not; it thus appears that the state of oxidation is a critical factor in the utilization of sulfur by these strains of S. bovis. A complex amino acid mixture, without sulfur-containing amino acids, produces more rapid and reproducible growth than either arginine or ammonium acetate when used as a nitrogen source for testing the sulfur compounds. Growth rates are frequently better when the sulfur sources are autoclaved than when they are sterilized by filtration, although the qualitative responses to the compounds are generally similar.