聚乳酸降解菌株筛选鉴定及降解过程优化

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

【目的】筛选能够降解聚乳酸的微生物,提高聚乳酸的降解速率并鉴定聚乳酸降解酶种类。【方法】以明胶为唯一碳源,筛选能够降解聚乳酸的微生物;通过优化明胶添加浓度、聚乳酸添加量以及金属离子种类提高聚乳酸的降解速率;通过分析降解过程中代谢产物和酶活力变化明确聚乳酸降解酶类别。【结果】筛选获得一株聚乳酸降解菌株,鉴定为Lentzea waywayandensis;经优化培养,聚乳酸在25 d后失重84.8%;降解过程中,检测到乳酸的产生,体外酶活实验仅检测到蛋白酶活力。【结论】明胶作为唯一碳源适用于聚乳酸降解菌株的筛选;明胶作为碳源的同时可以作为诱导剂诱导菌株L.waywayandensis降解聚乳酸;此外,研究表明蛋白酶在聚乳酸降解过程中发挥重要作用。

[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.