Isolation of a new Thermoanaerobacterium thermosaccharolyticum strain (FH1) producing a thermostable dextranase

[摘要] A Gram-positive spore-forming thermophilic strict anaerobic bacterium, designated FH1, was isolated from enrichments at 65°C with dextran as sole carbon and energy source. A sequence analysis of the 16S rRNA gene revealed 99.2% identity of FH1 to Thermoanaerobacterium thermosaccharolyticum. Furthermore, the substrate spectra of both organisms were similar. It was therefore concluded that FH1 represents a new strain within the species T. thermosaccharolyticum. The optimal growth temperature of strain FH1 was 68°C. The isolated organism produced a thermostable and thermoactive dextranase with a native molecular mass of approximately 200,000 Da. The enzyme was concentrated from the cell-free culture supernatant by ammonium sulfate precipitation. The resulting crude dextranase exhibited optimal activity from 65 to 70°C and a pH optimum of 5.5.

[学科分类] 微生物学和免疫学

[关键词] dextran degradationdextranase;;Thermoanaerobacterium thermosaccharolyticum;thermophilic bacteria