Lutispora thermophila gen. nov., sp. nov., a thermophilic, spore-forming bacterium isolated from a thermophilic methanogenic bioreactor digesting municipal solid wastes.

Abstract

A novel anaerobic, moderately thermophilic, spore-forming, rod-shaped bacterium (strain EBR46T) was isolated from an enrichment culture derived from an anaerobic thermophilic (55 degrees C) methanogenic bioreactor treating artificial solid wastes. Phylogeny based on 16S rRNA gene sequence analysis placed strain EBR46T within a distinct lineage between Clostridium clusters II and III. The closest recognized relative of strain EBR46T was Gracilibacter thermotolerans DSM 17427T (85.3 % 16S rRNA gene sequence similarity). The DNA G+C content of strain EBR46T was 36.2 mol%. The novel strain grew optimally at 55-58 degrees C and at pH 7.5-8.0 and was able to grow on peptone, tryptone, Casamino acids, casein hydrolysate, methionine, threonine, tryptophan, cysteine, lysine and serine in the presence of 0.2 % yeast extract. Carbohydrates were not utilized. The main products from tryptone utilization were acetate, iso-butyrate, propionate and iso-valerate. Strain EBR46T produced hydrogen sulfide from cysteine. The major fatty acids were iso-C15 : 0, C14 : 0, C16 : 0 DMA (dimethyl acetal) and iso-C15 : 0 DMA. Based on its unique phylogenetic and physiological features, strain EBR46T is considered to represent a novel species of a new genus, for which the name Lutispora thermophila gen. nov., sp. nov. is proposed. The type strain of the type species is EBR46T (=NBRC 102133T=DSM 19022T).