Enhancing production of alkaline polygalacturonate lyase from Bacillus subtilis by fed-batch fermentation

Alkaline polygalacturonate lyase (PGL, EC 4.2.2.2) is an enzyme used in many industries. We developed a fed-batch fermentation process that combines the enzymatic pretreatment of the carbon source with controlling the pH of the fermentative broth to enhance the PGL production from Bacillus subtilis 7-3-3 to decrease the production cost. Maintaining the fermentation broth at pH 6.5 prior to feeding with ammonia and at pH 6.0 after feeding significantly improved PGL activity (743.5 U mL-1) compared with the control (202.5 U mL-1). The average PGL productivity reached 19.6 U mL-1 h-1 after 38 h of fermentation. The crude PGL was suitable for environmentally friendly ramie enzymatic degumming.