Production of an alkali tolerant extracellular xylanase from Bacillus pumilus VLK-1 in solid state fermentation and its use in tomato juice clarification

Abstract

Xylanase production from Bacillus pumilus VLK-1 in solid state fermentation was enhanced through optimization of the process using one variable approach. The enzyme production was highest (42324±786 IU/g) upon 96h of incubation at 37°C using wheat bran as a substrate moistened with mineral salt solution (pH 9.0) containing 0.1% folic acid, 0.2% riboflavin and 6.0% yeast extract in the ratio of 1:2.5. Addition of Tween 80 to the extraction buffer increased the enzyme yield. An optimization of the fermentation conditions increased the 5.7-fold xylanase production. The augmentation of enzyme production using cheap and abundantly available wheat bran is likely to reduce the cost of enzyme for its industrial application. The purified xylanase showed its optimum efficiency in tomato juice enrichment on treatment of fruit pulp with enzyme (20 IU/g) at 40ºC for 30 min. Treatment of tomato pulp with purified xylanase increased juice yield (68%), clarity (7%), reducing sugars (192%), titratable acidity (19%), and filterability (8%) whereas reduced the viscosity by (8%) indicating an improvement in physico-chemical characteristics of the juice. The results showed that purified B. pumilus VLK-1 xylanase could be exploited for fruit juice enrichment.