Enhanced production of poly(vinyl alcohol)-degrading enzymes by mixed microbial culture using 1,4-butanediol and designed fermentation strategies

Nowadays, poly(vinyl alcohol) (PVA) has caused serious pollution in the natural environment. To eliminate PVA pollution, PVA-degrading enzymes (PVADE) were studied. Previously our group has detected PVADE in a mixed microbial culture. In this study, it was found that 1,4-butanediol could enhance PVADE production. High PVADE activity (3.43 U ml−1), which was 4.6 folds of the control (0.75 U ml−1), was achieved with 1,4-butanediol as carbon source. Concomitantly, the average PVA-degrading rate improved 2.0 folds compared to the control. Specifically, diauxic growth coupled with increased PVA-degrading rate was observed. Based on this phenomenon, two-stage fermentation by adding another carbon source at a proper time was designed. By applying this strategy, high PVADE productivity (60.8 U l−1 h−1) was achieved. Further, the two-stage fermentation was extended to three-stage fermentation by adding PVA to improve PVADE production. The PVADE activity per unit biomass (YPVADE/x) was significantly enhanced over two-stage fermentation and the maximum increment was 418 U g−1.