Characterization and optimization of xylanase producing strain of Bacillus subtilis isolated from the cabbage looper (Trichoplusia ni (Hübner)) intestine

Abstract

Aims: To characterize xylanolytic enzyme producing strains of Bacillus subtilis from the intestinal tract of a cabbage looper (Trichoplusia ni (Hübner)) larvae. Methodology and results: Approximately 5 g of intestinal content from the instar larvae were homogenated and serially diluted 10-4 -10-6 times with sterile normal saline before being spread onto duplicate tryptic soy agar plates. Every different colony was selected to test for xylanase production. Of six isolates, only one was found to be positive for xylanase production by screening agar. Biochemical characteristics and 16S rRNA gene sequencing indicated that the Bact-I was closely related to Bacillus subtilis. Optimization of xylanase enzyme production showed that Bacillus subtilis was able to produce xylanase enzymes when grown in a culture medium containing 2% (w/v) corn stover and 0.6% (w/v) yeast extract at pH 10 and 37 °C. The xylanase gene was cloned and characterized. The result revealed that the xylanase gene of Bacillus subtilis was homology to the β-1,4 endo-xylanase gene. Conclusion, significance and impact of study: A xylanase producing Bacillus subtilis was isolated from the intestinal tract of a cabbage looper (Trichoplusia ni (Hübner)) larvae. Optimization and evaluation of the xylanase activity of Bacillus subtilis indicated that it could be useful for xylanase production or as a probiotic for improving animal feed stuff.