Isolation of a new Thermoanaerobacterium thermosaccharolyticum strain (FH1) producing a thermostable dextranase.
A Gram-positive spore-forming thermophilic strict anaerobic bacterium, designated FH1, was isolated from enrichments at 65 degrees 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 degrees 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 degrees C and a pH optimum of 5.5.
Hoster
Frank
F
Institut für Mikrobiologie und Genetik der Georg-August-Universität, Grisebachstrasse 8, D-37077 Göttingen, Germany.
Daniel
Rolf
R
Gottschalk
Gerhard
G