A new strictly anaerobic, alkaliphilic, moderately thermophilic, fermentative, spore-forming bacterium, strain K1T, was isolated from manure samples (pH 6-8). Cells were Gram-positive, straight, non-motile rods that grew at temperatures of 37-66 degrees C (optimum at 62 degrees C) and in a pH range of 8.0-10.5 (optimum at 9.5-9.7). The bacterium fermented D-glucose, sucrose, D-fructose, D-trehalose and starch as carbon and energy sources. It required vitamins and its growth is stimulated by yeast extract. The major metabolic products were H2 and acetate. Cells were catalase-negative and could reduce nitrate to nitrite. The G+C content of the DNA was 42.2 mol%. Based on the phenotypic properties and 16S rDNA sequencing and DNA-DNA hybridization data, strain K1T (= DSM 12423T = ATCC 700785T = VKM B-2193T) was assigned to the new genus Anoxybacillus gen. nov., as a representative of a new species, Anoxybacillus pushchinensis sp. nov. 'Bacillus flavothermus' strain d.y., which was found to be closely related to strain K1T, is described as Anoxybacillus flavithermus comb. nov. (type strain = d.y.T = DSM 2641T).

A sample from a hot spring on the northern island of New Zealand contained five different thermophilic bacterial strains. One strain with peculiar properties, i.e. the formation of dark yellow colonies at 30 degrees C as well as at 70 degrees C, was further characterized. It was found to be a gram-positive, facultatively aerobic, motile Bacillus species, with terminal endospores. According to the physiologic properties the strain closely resembled B. coagulans. However, two typical characteristics were contradictory to this conclusion, namely the intense yellow pigmentation of the colonies and the range of growth temperature. The latter was found to reach from 40 to 70 degrees C, with an optimum at 60 degrees C under aerobic and at 65 degrees C under anaerobic conditions. Growth at moderate temperatures was slower than at 60 degrees C, but the final cell yields were almost equal. The strain can therefore be considered as facultatively thermophilic. The pigment, which was found to be located in the cytoplasmic membrane, was spectroscopically identified as a carotenoid. Because the characteristics of this strain did not correspond with any of the Bacillus species described thus far, we concluded, that we had isolated a novel strain, for which the name Bacillus flavothermus is proposed.