Biochemical Characteristics of Vibrio sputorum and Relationship to Vibrio bubulus and Vibrio fetus

Loesche, Walter J. (Forsyth Dental Center and Harvard School of Dental Medicine, Boston, Mass.), Ronald J. Gibbons, and Sigmund S. Socransky. Biochemical characteristics of Vibrio sputorum and relationship to Vibrio bubulus and Vibrio fetus. J. Bacteriol. 89:1109–1116. 1965.—Twenty-seven strains of Vibrio sputorum were isolated from human gingival debris. All strains reduced nitrate beyond nitrite, and all produced H2S. None produced catalase, indole, or acetylmethylcarbinol. Carbohydrates were not fermented, and acid end products or volatile neutral products could not be detected. Motility was observed infrequently, although 14-hr cultures usually had a few cells which displayed darting motility. Shadowed electron microscopic preparations demonstrated that most cells in a given culture were nonflagellated, although some cells with a single terminal or subterminal flagellum were always observed. V. sputorum was demonstrated not to be a strict anaerobe as previously described, but rather a microaerophile. Addition of nitrate to culture media markedly enhanced growth. V. sputorum was found to be closely related to the animal microaerophilic vibrios, V. bubulus and V. fetus. V. sputorum differed from V. fetus by being capable of anaerobic growth, producing H2S, and failing to produce catalase or to grow in 10% O2. Antigens of V. sputorum cross-reacted in low titer with antisera to V. fetus serotypes I, II, III, and V. V. sputorum differed from V. bubulus by being inhibited by 3.5% NaCl and by qualitative differences in growth in the presence of 1% glycine and 10% O2. These differences do not appear sufficient to recognize two distinct species, and it is proposed that both species be recognized as V. sputorum, which has priority. Strains unable to grow in 3.5% NaCl would be considered V. sputorum var. sputorum, whereas strains capable of growth in 3.5% NaCl would be V. sputorum var. bubulum.