Objective Microbes with high efficiency in degrading polyethylene terephthalate-adipate (PBAT) mulch film were isolated from farmland soil and studied.

Method Using PBAT as the sole carbon source on a dimethyl terephthalate (DMT) identification medium, microorganisms exhibiting high PBAT degradation ability were isolated from the soil collected at farmlands in Fujian Province that had a long history of using the film for mulching. The isolates were identified by 16sRNA gene sequencing with HPLC verified PBAT-degrading capacity. Quantified degradation of the strains was determined by the weight loss rate determination, Fourier transform infrared (FTIR) spectroscopy, water contact angle (WCA) determination, and scanning electron microscopy (SEM).

Result Nine PBAT-degrading strains of microbes belonging to 9 different genera and species were isolated. Among them, Variovorax guangxiensis MX4-3 delivered the highest film degradation rate of 7.63%±0.23% after 30d of culture at 28°C in a R2A medium. In addition, the SEM images showed significant gullies and folds on the film surface, the WCA measurement indicated a significant hydrophobicity reduction of the film, and the absorption peak of the characteristic PBAT functional groups on the FTIR spectrum was lowered reflecting a disrupted molecular structure of the film.

Conclusion Nine strains of microbes capable of degrading PBAT film were isolated. V. guangxiensis MX4-3 displayed the greatest degradation ability and was considered for further study to mine the responsible genes and field experimentation to develop a bioagent that would benefit environmental conservation.