Degradation of polylactic acid/polybutylene adipate-co-terephthalate blend by Papiliotrema laurentii S2P4P isolated from agricultural soils

Polylactic acid/polybutylene adipate-co-terephthalate blend (PLA/PBAT) has been widely used due to their good biodegradation. Recently, the biodegradation of PLA and PBAT has received increasing attention. However, PLA/PBAT blend-degrading strains have been rarely reported in comparison to that for pure PLA and PBAT. A fungus strain, Papiliotrema laurentii S2P4P, was isolated from agricultural soils and identified. S2P4P can efficiently degrade commercial PLA/PBAT films at 30°C in mineral salt medium (MSM) and obtained about 14% of weight loss within 30 days of incubation. Additionally, rough and uneven surface of PLA/PBAT film with cracks and creases, increased hydrophilicity, changes in mechanical property, and decreased intensity of C=O and C-O bonds were observed after S2P4P treatments. The strain secreted esterase to catalyze the degradation of the ester bonds in PLA/PBAT blend, resulting in the production of degradation products such as butanediol, adipic acid, lactic acid and terephthalic acid as well as their oligomers. Furthermore, as carbon and energy sources, the degradation products could participate in the metabolism of S2P4P and then accelerate degradation of PLA/PBAT blend. The advantages of P. laurentii S2P4P in simultaneous degradation of PLA and PBAT indicated that the strain has potential value for the bioremediation of PLA/PBAT blend in the actual environment.