Valorization of Agro-Industrial Waste for Pectinase Production by Bacillus subtilis SK16: A Step Toward Circular Bioeconomy

Pectinase is an industrially important enzyme with wide-ranging applications in the food, textile, and biofuel industries. However, commercial production remains cost-intensive due to the use of high-purity substrates. In this study, a cost-effective and sustainable bioprocess was developed to enhance pectinase production using agro-industrial pectin-rich waste materials, in alignment with the United Nations Sustainable Development Goals 2030. Bacillus subtilis SK16 was identified as a potent pectinase producer with notable polygalacturonase activity. Additionally, B. subtilis SK16 demonstrated the ability to produce multiple industrially important extracellular enzymes, including amylase, xylanase, protease, cellulase, and lipase. In this study, pectinase produced by agro-industrial pectin-rich waste as a substrate. Among them orange peel (397 U/ml), wheat bran (330.97 U/ml), and apple peel (207.9 U/ml) were evaluated as individual substrates for enzyme production. To further enhance enzyme yield, a combinational substrate approach was applied. By adjusting the proportions of these waste components, the study aimed to determine the most effective combination for maximizing pectinase yield. A maximum pectinase activity of 615.90 U/ml was achieved with a substrate combination of 0.5% orange peel and 1.5% wheat bran, reflecting a 55% enhancement compared to the highest yield obtained from individual substrates. This study underscores the potential of utilizing agro-industrial wastes as sustainable substrates for enzyme production, promoting efficient solid waste bioconversion while offering an eco-friendly and economically viable solution for environmental waste reduction. The findings contribute to waste valorization, circular bioeconomy, and reduced reliance on synthetic media, thereby supporting environmental sustainability and industrial scalability.