Simplified enzyme activity-based screening of microorganisms from Korean fermented foods for food-waste decomposition

Several options are available to encourage the degradation of food waste, but microbial approaches have attracted attention due to their efficiency and sustainability. Among various microorganisms, Bacillus species are notable for their ability to degrade starch, protein, and cellulose, making them ideal candidates for food-waste management. While methods of isolating and measuring the activity of individual Bacillus enzymes are well established, few attempts have been made to evaluate enzyme activity directly in Bacillus cultures without purification. In this study, we screened various methods of measuring enzyme activity and developed a simplified approach using agar plate assays and direct measurement of reaction products in liquid cultures without purification. Bacillus strains were isolated from traditional Korean fermented foods and their ability to degrade food waste was evaluated. Among 56 isolates, six superior strains were identified and combined to form a composite culture. This composite exhibited significantly higher enzymatic activity and food-waste degradation efficiency compared with commercial microbial preparations, achieving superior volume-reduction rates under industrial conditions. This study highlights the feasibility of measuring enzymatic activity directly in microbial cultures and identifies a promising composite culture for sustainable food-waste management. Our findings demonstrate the feasibility of using simplified enzyme assays for microbial screening and food-waste degradation applications.