Development of biodegradation process for Poly(DL lactic acid) degradation by crude enzyme produced by Actinomadura keratinilytica strain T16 1
Abstract Background Plastic waste is a serious problem because it is difficult to degrade, thereby leading to global environment problems. Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester derived from renewable resources, and it can be degraded by various enzymes produced by microorganisms. This study focused on the scale up and evaluated the bioprocess of PLA degradation by a crude microbial enzyme produced by Actinomadura keratinilytica strain T16 1 in a 5 L stirred tank bioreactor. Results PLA degradation after 72 h in a 5 L bioreactor by using the enzyme of the strain T16 1 under controlled pH conditions resulted in lactic acid titers (mg/L) of 16,651 mg/L and a conversion efficiency of 89% at a controlled pH of 8.0. However, the PLA degradation process inadvertently produced lactic acid as a potential inhibitor, as shown in our experiments at various concentrations of lactic acid. Therefore, the dialysis method was performed to reduce the concentration of lactic acid. The experiment with a dialysis bag achieved PLA degradation by weight loss of 99.93% whereas the one without dialysis achieved a degradation of less than approximately 14.75% Therefore, the dialysis method was applied to degrade a commercial PLA material (tray) with a conversion efficiency of 32% which was 6 fold more than that without dialysis. Conclusions This is the first report demonstrating the scale up of PLA degradation in a 5 L bioreactor and evaluating a potential method for enhancing PLA degradation efficiency. How to cite: Panyachanakul T, Sorachart B, Lumyong S, et al. Development of biodegradation process for Poly(DL lactic acid) degradation by crude enzyme produced by Actinomadura keratinilytica strain T16 1. Electron J Biotechnol 2019;40. https:/doi.org/10.1016/j.ejbt.2019.04.005
Electronic Journal of Biotechnology