Leveraging pH profiles to direct enzyme production (cellulase, xylanase, polygalacturonase, pectinase, α-galactosidase, and invertase) by Aspergillus foetidus

Aspergillus foetidus was found to have different optimal pH conditions for producing different carbohydrases including cellulase, xylanase, pectinase, α-galactosidase, polygalacturonase, and invertase. Designs to trigger these conditions sequentially using controlled pH gradients were evaluated for directing the culture through multiple production stages optimal for different enzymes. For production of enzyme mixtures with particularly high pectinase and α-galactosidase activities, for more effective hydrolysis of the complex carbohydrate in soybean meal, the best method tested was a pH gradient started at pH 7.0, decreased to pH 6.0 over 72 h, held constant for 24 h, and then decreased to pH 5 over 24 h.