Isolation, identification of poly lactic acid degrading microorganisms and optimization of the degradation process

Abstract:

[Objective] The study aims to screen microorganisms capable of degrading poly lactic acid (PLA), improve the degradation rate and identify degrading enzymes. [Methods] Gelatin was used as sole carbon source to screen PLA degrading microorganisms. To increase the PLA degradation rate, concentration of gelatin, weight of PLA added and metal ions were optimized. By investigating and comparing metabolites and enzyme involved, we determined the category of PLA degradation enzymes. [Results] A PLA degrading strain was screened and identified as Lentzea waywayandensis. After optimization, 84.8% loss of PLA was achieved (25 d). Lactic acid as metabolite was detected during cultivation. Moreover, only obvious protease activity was observed in vitro experiments. [Conclusion] Gelatin was applicable for screening PLA degrading microorganisms. Besides acting as carbon source, gelatin could also be used as an inducer to strengthen L. waywayandensis to degrade PLA. Furthermore, the results obtained herein suggested that protease played an important role on PLA degradation.

Key words:Poly lactic acid, Lentzea waywayandensis, gelatin, optimization, protease