Xanthobacter flavus, a New Species of Nitrogen-Fixing Hydrogen Bacteria

Abstract

Mycobacterium flavum strain 301 (= Deutsche Sammlung von Mikroorganismen 338), a hydrogen-utilizing bacterium, is capable of fixing molecular nitrogen and resembles other nitrogen-fixing hydrogen bacteria. However, it is clearly different in many characters from other strains of M. flavum (Orla-Jensen) Jensen (syn.: Microbacterium flavum Orla-Jensen). It does resemble strains of Xanthobacter Wiegel et al. with respect to cell wall composition, production of carotenoid pigments, carbon source utilization pattern, and deoxyribonucleic acid (DNA) base composition (69 mol% guanine + cytosine). Strain 301 is here regarded as belonging to a new and distinct species, for which the name Xanthobacter flavus is proposed. Strain 301 is the type strain of this species. X. flavus differs from Xanthobacter autotrophicus, the only other species in this genus to date, in several respects, and the DNA-DNA hybridization between X. flavus and X. autotrophicus is only 25%.