Valorization of rice milled by-products (rice husk and de-oiled rice bran) into α-amylase with its process optimization, partial purification and kinetic study

Abstract

A massive amount of waste is generated globally from agriculture sector annually that offers potential feedstock for biorefineries. Undoubtedly α-amylase has become the backbone of starch-based industries. It is a crucial amylolytic enzyme possessing versatile applications. An expensive synthetic substrate that is non-eco-friendly and toxic is not sustainable enough for large scale enzyme production. The agricultural residues should be employed as they are the low-budget production medium with high yield and are eco-friendly. Thus, current study deals with the valorization of agricultural by-products for α-amylase production. Two divergent rice-milled by-products (de-oiled rice bran and rice husk) were investigated to ascertain the best economical medium for α-amylase production. The study deals with production, partial purification and kinetics analysis of α-amylase from rice milled by-products by two bacteria (Staphylococcus aureus MTCC 3160 and Bacillus subtilis MB6). Out of all combinations, the best production (161.45 ± 2.60 U/mL) was obtained in DORB_S. aureus. The Km and Vmax values of DORB_S. aureus were 1.468 mg/mL and 34.722 mg/mL/min respectively. The study provides a roadmap for significant consumption of agricultural by-products. The study highly recommends researchers to explore some more agricultural residues as an eco-friendly and inexpensive medium to synthesize various bio-products under green technology.