Anaerosphaera aminiphila gen. nov., sp. nov., a glutamate-degrading, Gram-positive anaerobic coccus isolated from a methanogenic reactor treating cattle waste

Abstract

A strictly anaerobic, mesophilic and aminolytic strain (WN036(T)) was isolated from a methanogenic reactor treating waste from cattle farms. Cells were Gram-positive cocci, often occurred in pairs and were non-motile. Although spore formation was not confirmed by microscopic observation of cells, the strain produced thermotolerant cells. The optimum temperature for growth was 35-37 degrees C and the optimum pH was 6.7. Oxidase, catalase and nitrate-reducing activities were negative. The novel strain did not ferment carbohydrates and grew in PY medium without additional substrates. The strain utilized l-glutamate, l-glutamine, l-histidine and l-arginine as growth substrates. Major fermentation products were acetate and butyrate with a small amount of propionate. The genomic DNA G+C content was 32.5 mol%. The major cellular fatty acids were C(17 : 1)omega8, C(18 : 1)omega7 DMA and C(16 : 0). The diagnostic diamino acid of the cell-wall peptidoglycan was lysine. Glutamic acid, glycine, alanine and aspartic acid were also detected in the cell-wall peptidoglycan. On the basis of 16S rRNA gene sequences, the most closely related species to strain WN036(T) were Peptoniphilus asaccharolyticus ATCC 14965(T) (89.8 %) and Peptoniphilus indolicus ATCC 29427(T) (89.6 %). Based on the differences in the phenotypic and phylogenetic characteristics of strain WN036(T) compared with those of closely related species, a novel genus and species, Anaerosphaera aminiphila gen. nov., sp. nov., is proposed. The type strain is WN036(T) (=JCM 15094(T)=DSM 21120(T)).