一株聚乳酸降解菌的筛选、鉴定及其降解特性

Screening,identification,and degradation characterization of a polylactic acid-degrading bacterial strain

摘要:

【目的】分离可有效降解聚乳酸(polylactic acid,PLA)的好氧细菌，并研究其生长特性和降解特性，为环境中PLA废弃物的生物修复提供依据。【方法】通过16S rRNA基因序列分析对所筛选菌株进行分子生物学鉴定，采用扫描电镜和傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FTIR)分析降解前后PLA膜的形貌和化学结构变化。【结果】从活性污泥中筛选获得一株芽孢杆菌(Bacillus sp.) JA-4，30 d后PLA失重率可达10.6%。pH 8.0、30℃以及接种量20%的条件下，7 d后PLA的失重率可达到5.6%。明胶对PLA的生物降解具有显著促进作用，当明胶浓度为3%时，降解10 d后PLA的失重率达到23.1%，降解速率也大大提高。FTIR分析表明该菌株通过水解酯键来实现PLA的降解。【结论】本研究为PLA的生物降解提供了新的微生物资源，为环境中PLA废弃物的有效降解提供技术支持。

Abstract:

[Objective]We isolated the aerobic bacteria capable of effectively degrading polylactic acid (PLA) and characterized the bacterial growth and degradation,aiming to lay a theoretical foundation for the bioremediation of PLA contaminated environment.[Methods]The degrading bacterium was identified by 16S rRNA gene sequencing.Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were employed to analyze the morphological and chemical changes of PLA films before and after degradation.[Results]A strain of Bacillussp.JA-4 was screened from activated sludge,and it caused the PLA weight loss of 10.6% after 30 days.The weight loss of PLA reached 5.6% after incubation with the strain at an inoculation amount of 20%,pH 8.0,and 30℃ for 7 days.Gelatin significantly enhanced the biodegradation of PLA.In the presence of 3% gelatin,the weight loss of PLA reached 23.1% after 10 days of degradation,and the degradation rate was greatly increased.FTIR results indicated that Bacillussp.JA-4 degraded PLA by hydrolyzing the ester bonds.[Conclusion]This study enriched the microbial resources for the biodegradation of PLA and provided technical support for the effective degradation of PLA waste in the environment.