Purification and Characterization of a Recombinant Thermostable ?-mannanase from Thermotoga maritima / 微生物学通报

ABSTRACT

A ?-mannanase gene (TM_1227) from Thermotoga maritima MSB8 was cloned and expressed in E.coli. The recombinant ?-mannanase was purified and characterized. The gene consists of 2010 bp, and the translated protein encodes 669 amino acids and its molecular mass is approximately 76.827 kD. Homology analysis of the deduced amino acid sequences showed that the enzyme shared 99% identity with ?-mannanase from Thermotoga sp. RQ2. The mannanase activity was up to 39.7 U/mg after the recombinant E. coli BL21 was induced by IPTG. Crude enzyme solution was purified to homogeneity by Ni-NTA agarose. Its optimum temperature and pH was 95?C and pH 8.0 respectively for LBG. The enzyme remained over 50% activity after treated at 85?C for 30 min. The above properties showed great potential of its application in paper industry. The mannanase hydrolyzed copra mannan and LBG to give various sizes of oligosaccharides, and almost no mannose was detected by TLC, which was suitable for mannooligosaccharides production.