Pretreatment of agricultural residues by cellulase and xylanase enzymes produced by a Bacillus sp.

beta -1,4 xylanase and endoglucanase enzymes designated as FR1 and FR2 were fractionated from the cultural supernatant of a Bacillus sp. growing on rice husk, an agricultural residue. The fractionation of the enzyme components and further purification steps were carried out on anion exchange chromatography on FPLC Mono Q column followed by gel filtration on FPLC Superose-12 Column. The purified preparation on SDS-PAGE revealed molecular masses of 46.1 kDa for FR1 and 56.2 kDa for FR2. Both the enzymes exhibited pH optima in the acidic range between 4 and 6. Temperature optima for FR1 and FR2 were observed at 50 degrees and 60 degrees C, however FR1 was more stable as compared to FR2. Both the enzymes displayed specificities for beta-1,4 linkages since beta-1,3 linked compounds like starch and laminarin were not cleaved at all. The purified preparation of xylanase did not show any affinity towards xylobiose whereas endoglucanase exhibited partial affinity towards cellobiose.