CHARACTERIZATION AND DESCRIPTION OF HYPHOMICROBIUM DENITRIFICANS SP, NOV

The Hyphomicrobium strains which we examined in this study are gram ne gative and facultatively methylotrophic and utilize methanol and monom ethylamine, but not methane, by the serine pathway with activated form aldehyde incorporation. The cellular fatty acids include a large amoun t of straight-chain unsaturated C-18:1 acid, and the hydroxy fatty aci ds include large amounts of 3-OH C-14:0 and 3-OH C-16:0 hydroxy acids. The major ubiquinone is ubiquinone Q-9. However, the DNA base composi tions of these Hyphomicrobium strains are heterogeneous, ranging from 58 to 66 mol% guanine plus cytosine. Strains TK 0415(T) (T = type stra in), TK 0414, TK 0416, and TK 0441 were distinguished from other Hypho microbium strains on the basis of physiological characteristics and DN A-DNA hybridization data. A new species, Hyphomicrobium denitrificans, is proposed for these organisms; the type strain of H. dentrificans i s TK 0415 (= DSM 1869 = NCIB 11706 = Attwood and Harder strain X).