Cost-Effective Production and Optimization of Alkaline Xylanase by Indigenous Bacillus mojavensis AG137 Fermented on Agricultural Waste

الملخص EN

A xylanase producer Bacillus mojavensis strain, called AG137, isolated from cotton farm (Kashan-Iran).

The optimal xylanase activity reached at 55∘C & pH 9.0.

Enzyme yield was studied using a medium with different agricultural wastes as inducers.

Xylanase production of about 249.308 IU/mL was achieved at pH 8 and 37∘C, within 48 h submerged fermentation in enzyme production medium supplemented with 2% (w/v) oat bran as an optimum carbon source.

A mixture of 1% (w/v) yeast extract and 1% (w/v) tryptone as optimum nitrogen sources, agitation speed 200 rpm, and inoculum size 2% (v/v) were the optimums for maximum production.

Accordingly, xylanase yield from 194.68 IU/mL under non-optimized fermentation condition enhanced to 302.466 IU/mL in optimized condition.

Screened xylanase is thermostable, presenting 70% stability at 60∘C during 30 min.

Further enzyme incubation in higher temperature caused a decrease in the residual enzyme activity, yet it retained 68%–50% of its activity after 1 hour from 45∘C to 55∘C.

Besides, it is stable in pH 9 and 10, maintaining over 70% of its activity for 2 h.

The enzyme also could preserve 71% and 63% of its initial activity after 3 hours of pre-incubation in the same alkaline condition.

Produced xylanase therefore was introduced as an alkaline-active and stable one, displaying suitable thermostability feature, confirmed by HPLC analysis.

Hence, all xylanase properties highlight its promising uses in industrial scale.