Halomonas desiderata sp nov, a new alkaliphilic, halotolerant and denitrifying bacterium isolated from a municipal sewage works

Studies on the degradation of nitrocellulose have shown that a combination of chemical and biological methods may be applicable. Chemical degradation involves alkaline hydrolysis followed by biological removal of the hydrolysed material (organic material, nitrate and nitrite) under alkaline conditions. Enrichment cultures from samples of the Gottingen municipal sewage treatment plant resulted in the isolation of an alkaliphilic organism capable of dissimilatory nitrate reduction. Investigations revealed that the organism expressed all enzymes necessary for the complete reduction of nitrate to N-2. Optimal denitrification, which was induced by oxygen limitation, as well as optimal growth appeared between pH 9 and 10, Under these conditions N-2 was the main denitrification product. A combination of chemical (polar lipids, respiratory lipoquinones, and fatty acids) and 16S rDNA analysis showed that the isolate was a member of the Halomonas/Deleya complex within the gamma-subclass of the Protobacteria, Based on the data obtained from a biochemical and physiological characterisation, together with the chemical and 16S rDNA data, it was possible to show that the isolate was a novel organism within this clade. Due to uncertainties associated with the current delineation of taxa within this taxonomic complex it is proposed that the organism be assigned to a new species within the genus Halomonas as Halomonas desiderata sp. nov.