Nitrogen Fixation by Sporulating Sulphate-reducing Bacteria Including Rumen Strains

Abstract

The acetylene test for nitrogen fixation has been an important tool in reassessing the ability of various groups of micro-organisms to fix nitrogen (Parejko & Wilson, 1968; Millbank, 1969; Hill & Postgate, 1969). As a result of this reassessment, it has been found that several aerobic genera such as Azotomonas, Pseudomonas, Nocardia, Pullularia and yeasts probably do not fix N2; on the other hand, nitrogen fixation has proved to be far more widespread among the sulphate-reducing bacteria of the genus Desulfovibrio than was earlier thought (Reiderer-Henderson & Wilson, 1970). This communication reports evidence for fixation by type strains of mesophilic, spore-forming, sulphate-reducing bacteria, genus Desulfotomaculum (Campbell & Postgate, 1965), including strains originating from the rumens of hay-fed sheep. Some data with type strains of Desulfovibrio are included to supplement the findings of Reiderer-Henderson & Wilson (1970).