Optimization of bacterial polygalacturonase production in apple pomace hydrolysate medium

Food and agricultural industries generate large amounts of waste during handling and processing. If not managed properly, this can overwhelm landfills and result in loss of valuable bioactive materials. Thus, this study aims at valorization of apple pomace for polygalacturonase (PGase) production. Specifically, the study describes Box-Behnken optimization of pectin addition along with its concentration and addition time, and fermentation duration to improve secretion of PGase enzyme by Bacillus subtilis NRRL B-4219. The results revealed significant enhancements in PGase production with a peak enzyme activity of 12.26 U/mL when 1 g/L of pectin was fed on the second day of a three-day fermentation. The obtained PGase activity was noted as the highest among our studies so far. Thus, Bacillus subtilis NRRL B-4219 was proven to require additional pectin to induce PGase secretion when grown in apple pomace hydrolysate medium. The study also demonstrates the ability of apple pomace to serve as an economical and sustainable resource for PGase production. By utilizing the apple pomace, the food industry can contribute to both reducing waste and creating valuable products.