Two new species of anaerobic oxalate-fermenting bacteria, Oxalobacter vibrioformis sp. nov. and Clostridium oxalicum sp. nov., from sediment samples

Two types of new anaerobic bacteria were isolated from anoxic freshwater sediments. They grew in mineral medium with oxalate as sole energy source and with acetate as main carbon source. Oxalate as well as oxamate (after deamination) were decarboxylated to formate with growth yields of 1.2–1.4 g dry cell matter per mol oxalate degraded. No other organic or inorganic substrates were used, and no electron acceptors were reduced. Strain WoOx3 was a Gramnegative, non-sporeforming, motile vibrioid rod with a guanine-plus-cytosine content of the DNA of 51.6 mol%. It resembled the previously described genus Oxalobacter, and is described as a new species, O. vibrioformis. Strain AltOx1 was a Gram-positive, spore-forming, motile rod with a DNA base ratio of 36.3 mol% guanine-plus-cytosine. This isolate is described as a new species of the genus Clostridium, C. oxalicum.