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

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.

Key words:polylactic acid;screening;biodegradation;Bacillussp.JA-4;weight loss