Gelria glutamica gen. nov., sp nov., a thermophilic, obligately syntrophic, glutamate-degrading anaerobe

A novel anaerobic, Gram-positive, thermophilic, spore-forming, obligately syntrophic, glutamate-degrading bacterium, strain TGOT, was isolated from a propionate-oxidizing methanogenic enrichment culture. The axenic culture was obtained by growing the bacterium on pyruvate. Cells were rod-shaped and non-motile. The optimal temperature for growth was 50-55 degreesC and growth occurred between 37 and 60 degreesC. The pH range for growth was 5.5-8 with optimum growth at pH 7. In pure culture, strain TGOT could grow on pyruvate, lactate, glycerol and several sugars. In co-culture with the hydrogenotrophic methanogen Methanobacterium thermautotrophicum strain Z-245, strain TGO(T) could grow on glutamate, proline and Casamino acids. Glutamate was converted to H-2, CO2, propionate and traces of succinate. Strain TGO(T) was not able to utilize sulphate, sulphite, thiosulphate, nitrate or fumarate as electron acceptors. The G+C content was 33.8 mol %. Sequence analysis of the 16S rDNA revealed that strain TGO(T) belongs to the thermophilic, endospore-forming anaerobes, though no close relations were found. Its closest relations were Moorella glycerini (92 %) and Moorella thermoacetica (90 %). Strain TGOT had an unusually long 16S rDNA of more than 1700 bp. The additional base pairs were found as long loops in the V1, V7 and V9 regions of the 16S rDNA. However, the loops were not found in the 16S rRNA. The name Gelria glutamica gen. nov., sp. nov. is proposed for strain TGO(T).