Production and Optimization of Xylanase Enzyme from Bacillus subtilis using Agricultural Wastes by Solid State Fermentation

Abstract

Background: Xylan, a major hemicellulosic polysaccharide found in the plant cell wall, represents up to 30-35% of the total dry weight of land plants. It is a heteropolysaccharide made up of a backbone of 1, 4-linked β-D-xylopyranosyl residues which can be substituted to varying degrees with glucopyranosyl, α-L-arabinofuranosyl, acetyl, feruloyl and/or p-couma- ryl side chain groups. Hemicelluloses are used in various industries such as fuel, food, detergent, animal feed, agriculture, wine, beer, pharmaceu- ticals and cosmetics. The main objective of the study is to explore easy and cost effective method to produce the xylanase using sugar cane ba- gasse, wheat bran and rice bran as substrates, which is an agro waste.Materials and Methods: Xylanase producing bacteria were isolated from soil. Among the isolates, three strains show the maximum activity on xylan agar plates. Among the three strains, a strain was shows maximum en- zyme activity, which was measured by Dinitro Salicylic Acid (DNS) method. The isolates were identified as Bacillus subtilis and which was identified by 16S rRNA gene sequence analysis. Optimization of the fermentation medium for production of maximum xylanase was carried out via solid state fermentation (SSF).Results: The highest production of xylanase was obtained on 3% xylose as a carbon source, 3% malt extract as a nitrogen source and 3% sugarcane bagasse at 40°C, pH 9, 3.5% Inoculum level at 48 hr. Bacillus subtilis are capable to produce the xylanase.Conclusion: The isolated strain Bacillus subtilis shows the maximum level of xylanase production at pH 9.0 and 40°C temperature on 48 hr incubation on 3% xylose, 3% malt extract and 3% sugarcane bagasse as a substrate during solid state fermentation.

Keywords: Bacillus subtilis; Xylanase; Sugarcane bagasse; Wheat bran; Rice bran