- Volume 128, Issue 11, 1982

Representatives of groups of mycoplasmas which have antigens in common with Mycoplasma mycoides (as demonstrated by different serological tests) were compared by nucleic acid hybridization. Determinations of DNA homology were performed by filter hybridization as well as hybridization in solution; no differences were revealed between the two methods. Genetic relatedness was not demonstrated between M. primatum and strain F38. The antigenic similarities between strain F38 and the type strain of M. primatum (HRC292) may be due to common epitopes. DNA from strain F38 hybridized with DNA from M. capricolum (California kid) to 80%, but only to about 40% with the two M. mycoides subspecies, a result which can justify the classification of the F38 group as a variant of M. capricolum. The representative strain of bovine serogroup 7 of Leach was equally distant from F38, M. capricolum and the two subspecies of M. mycoides (approximately 60% hybridization).

A new species in the family Bacteroidaceae is described, isolated from alkaline wetwoods of poplar trees. It was a non-sporing, curved rod that formed long spiral filaments, especially when grown with N2 as the sole nitrogen source. This obligate anaerobe had peritrichous flagellation and an outer-wall membranous layer. The DNA G + C content was 36·7 ± 1·0 mol %. Cell extracts displayed absorption peaks for type b cytochromes in oxidized versus reduced difference spectra. Nitrogenase was detected by acetylene reduction in cells grown on glucose in the absence of combined nitrogen. This species fermented lactate and a variety of saccharides. Propionate, acetate and CO2 were major products, with succinate and ethanol formed in trace quantities. The optimal pH and temperature for growth were 6·0–6·5 and 3033 C, respectively. The name Propionispira arboris gen. nov. sp. nov. is proposed for the type strain 12B4, which has been deposited as ATCC 33732.