Process optimisation of solid-state fermentation for maximum cellulase production by Bacillus sp. on banana peels waste

Abstract

Banana peels, an abundant agro-industrial residue rich in carbon and nitrogen, make it a viable low-cost substrate for bacterial growth and cellulase production. The present study employed response surface methodology (RSM) using central composite design (CCD) to systematically optimize key process parameters influencing cellulase production by Bacillus sp. FBT2 via solid-state fermentation (SSF). Five independent variables, namely initial pH, incubation temperature, substrate moisture content, Tween® 80 concentration, and inoculum size, were investigated for their influence on the enzyme production yield. After 72 h of fermentation under optimized conditions (pH 7.0, 30 °C, 60% moisture, 0.2% Tween® 80, and an inoculum size of 10⁸ spores/g) resulted in a maximum cellulase activity of 3.31 U/g, which closely matches the predicted value of 3.29 U/g, confirming the reliability of the statistical model. The current study demonstrates that utilizing banana peels as a solid substrate in SSF, combined with process optimization, offers environmental benefits through waste reduction and potential cost savings in cellulase production.

Keywords

Agro-industrial residues / Banana peels / Cellulase / Response surface methodology / Solid-state fermentation

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Jiangnan University