Optimization, Isolation and Characterization of Cellulase–Free Thermostable Xylanase from Paenibacillus sp.

Xylanases are hydrolytic enzymes that cleave the β-1,4-linkage ofwheat bran xylan. For screening of xylanase producing bacteria soil samples were diluted by serial dilution and cultured on selective wheat bran xylan agar media. Two bacterial strains showing clear transparent zone around the colony on xylan agar plate were selected as xylanase producing bacteria. The strain Paenibacillus sp. showed highest xylanolytic activity. The strain was thermophile and produced highly active cellulase free xylanase. The enzyme secretion was enhanced when the medium was supplemented with 0.5% wheat bran xylan, peptone and Ca 2+ salt. The peak in xylanase production was achieved within 48-60 hours at temperature 50°-55°C and at pH 7.0.The cellulase free xylanase was partially purified by ammonium sulfate fractionation and heat treatment at 50°C. The xylanase was optimally active at pH 7.0 and 55°C; and showed high substrate activity to wheat bran xylan but no activity towards carboxymethylcellulose, cellulose and starch.In future we want to know the structure function relationship of the purified enzyme and also want to known the molecular biological study using highly purified xylanase. For this purpose we have to determine the N-terminal & C-terminal amino acid sequence.