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.
ABSTRACT
The cloning and expression of a?-galactosidase gene(TM_0310)from Thermotoga maritima MSB8 was studied.The gene consists of 2019 bp,and the translated protein encodes 672 amino acids and its molecular mass is approximately 78.972 kD.The homology analysis of the deduced amino acid sequences showed that the enzyme shared 95%identity with a putative?-galactosidase from Thermotoga petrophila RKU-1 and a?-galactosidase from Thermotoga sp.RQ2.The galactosidase activity was up to 2.08 U/mg after the recombinant E.coli BL21 was induced by IPTG.The crude lysate remained about 70%activity after treated at 80℃for 10 min,indicating that the recombinant enzyme is thermostable and may be used at high temperatures.
ABSTRACT
A new thermophilic fungus J18 isolated from the soil samples was identified as Paecilomyces thermophila. This strain produced effectively xylanase utilizing several lignocellulosic materials in the solid-state fermentation (SSF) , and wheat straw was the best carbon source. The results of single-factor-experiment showed that the wheat straw of particle size 0. 3 mm ~ 0.45 mm, initial moisture content of 83% , initial pH of 7. 0 and cultivation temperature of 50℃were the optimal conditions for xylanase production. Under the optimized conditions, it produced 18 580 U/g dry substrate after 8 days of cultivation. Therefore, xylanase production by Paecilomyces thermophila in SSF possess great potential for commercial applications.
ABSTRACT
A xylanase producing strain was screened with xylan as the only carbon source. The strain was identified as Streptomyces cirratus. The effects of different factore on the enzyme production were studied. Corncobs xylan (water insoluble) and tryptone were the best C and N sources, respectively. The enzyme activity was increased to about 2.5 times by addition of 0.5% Tween 80 in the medium. The highest xylanase activity was up to 623u/mL.