Optimization of Phytase Production by Bacillus sp. (HCYL03) under Solid-State Fermentation by Using Box-Behnken Design

HIGHLIGHTS

• Bacillus sp (HCYL03) was capable of producing phytases under solid-state fermentation.

• Wheat bran, residue of the rolled milled wheat grain, showed, indeed, potential to be used in phytases production.

• Using wheat bran to attain bioproducts can reduce some social/environmental issues.

Abstract

Phytase production by Bacillus sp. (HCYL03) isolated from soil was investigated by solid-state fermentation (SSF) using wheat bran as substrate. After screening, morphological and molecular identification, Bacillus sp. (HCYL03) was selected for experiments due to high phytase activity. The SSF conditions were optimized by using one-variable-at-a-time strategy. A Box-Behnken design was employed to investigate the optimization of the most significant variables affecting the enzyme production. Maximum enzymes production was observed after 72 hrs with inoculums 2mL at 45^oC and pH 5. Maximum partial purification was obtained with 60% ammonium sulfate. Protein contents in crude extract and partially purified enzyme were found to be 9.58 and 3.95 mg/mL, respectively. Optimum temperature and pH of the partially purified phytase after characterization were found to be 45^oC and 5, respectively. The study of different metal ions sources revealed that Ca²⁺ and Mg²⁺ ions registered the highest enzyme productivity) but Zn²⁺, Cu²⁺, Cd²⁺, Mn²⁺and Fe²⁺ ions exhibited inhibitory effect on phytase activity. Briefly, the Bacillus sp. (HCYL03) production of phytase utilizing the low-cost agro-residue wheat bran as substrate is an innovative and cheap way for the production of this important enzyme and opens a new way for researchers to investigate this dome.

Keywords:
phytase; wheat bran; response surface methodology; solid-state fermentation.