Fermentation of S-citramalate,citrate, mesaconate,and pyruvate by a gram-negative strictly anaerobic non-spore-former,Formivibrio citricus gen. nov., sp. nov.

Two strains of S-citramalate-fermenting strictly anaerobic non-spore-formers were isolated in pure culture from anoxic mud samples of a creek and from a pond. One of them (strain CreCit 1) was studied in detail. It stained gram-negative, and contained β-hydroxymyristic acid. Nitrate, sulfate and other sulfur compounds were not utilized as electron acceptors. S-citramalate, citrate, mesaconate, and pyruvate were utilized as substrates; but R-citramalate, citraconate, l-glutamate, and carbohydrates not. S-citramalate was fermented to acetate, formate, and hydrogen. Citrate, mesaconate, and pyruvate were fermented to acetate and formate. The DNA base ratio was 59 mol% guanine plus cytosine. Strain CreCit 1 is described as a member of a new genus and a new species in the family Bacteroidaceae, Formivibrio citricus gen. nov., sp. nov.