Induction and repression of beta-xylanase of Thermomyces lanuginosus TISTR 3465

Analysis of inducers of xylanase and cellulase activities production by Ganoderma applanatum LPB MR-56

This manuscript describes the analysis of the effect of cellulose, carboxymethylcellulose (CMC), xylan, and xylose as inducers of cellulase and xylanase activity production by Ganoderma applanatum MR-56 and the optimization of their production in liquid cultures by statistical methods. The Plackett-Burman screening design was applied to identify the most significant inducers of xylanase and cellulase activities production by G. applanatum MR-56. The most significant effect on xylanase and cellulase activities production was exercised by cellulose, even if xylose and CMC were also effective at some times. The combined effect of cellulose, yeast extract, and pH was analyzed by a 2(3) factorial experimental design with four central points that showed that the maximum tested cellulose (1 % w/v) and yeast extract (5 g L(-1)) concentrations gave the maximum production of xylanase (8.24 U mL(-1)) and cellulase (3.29 U mL(-1)) activity at pH 6 and 4, respectively. These values achieved for cellulase and xylanase activity represent 12-25 fold and 36 fold higher values than the maximum so far reported for other strains of G. applanatum, respectively.

Regulation of xylanase biosynthesis in Bacillus cereus BSA1

Microbial xylanases have a promising biotechnological potential to be used in industries. In this study, regulation of xylanase production was examined in Bacillus cereus BSA1. Xylanase production was induced by xylan. The enzyme production further increased in the presence of xylose and arabinose in very low concentration with addition of xylan (0.5% up to 6.02 U/ml). Addition of glucose (about 0.1%) to the media supplemented with xylan repressed xylanase production. Even higher concentration (>0.1%) of xylose and arabinose repressed xylanase biosynthesis. Glucose-mediated repression was partially relived by addition of cyclic adenosine monophosphate. Chemical like 2-4-dinitrophenol, which can inhibit adenosine triphosphate synthesis in cell, repressed xylanase synthesis and it suggested xylanase synthesis to be an energy dependent process.

Beta-xylanase from Thermomyces lanuginosus and its biobleaching application

Thermomyces lanuginosus is thermophilic fungus in which was isolated from widespread material. A high number of this fungus was found in composts especially mushroom composts. This fungus has been reported to produce a high level xylanase when cultivated in the medium containing xylan and corn cob as a carbon source. Various strains of T. lanuginosus produced a single xylanase with molecular masses in range of 22.0 to 29.0 kDa. Pure beta-xylanase obtained from various strains of this fungus exhibited highly stability at high temperature and wide pH range. The optimal temperature and optimal pH of pure beta-xylanase from various strains of T. lanuginosus have been reported in range of 60-75 degrees C and pH 6.0-7.0, respectively. The great thermal stability was resulting from the present of hydrophilic amino acid on beta sheet of the surface of xylanase structure. Moreover, the relatedness between high and low xylanase producing strains can be distinguish by random amplification of polymorphic DNA (RAPD). Based on nucleotide sequences and T. lanuginosus xylanase gene has been classified to be a member of family 11 (formerly known as cellulase family G) glycosyl hydrolases. This enzyme was endo-type xylanase having main product are xylose and xylobiose. The expression of xylanase gene from T. lanuginosus was achieved in Escherichia coli and methylotrophic yeast Pichia pastoris. The ability of T. lanuginosus in which produced large amount of high thermos stable xylanase has made this fungus to be a source of xylanase production for biobleaching in pulp and paper process.