A yak gut probiotic Lactobacillus paracasei T1-9 displays superior degradation of poly(butylene adipate-co-terephthalate) bioplastic

Poly(butylene adipate-co-terephthalate) (PBAT) has gained significant attention for its exceptional processing properties and biodegradability. However, PBAT displays low biodegradability in natural environment. Many studies found degradable microorganisms in wastewater sludge, soil, compost, etc., but most are harmful to humans. This work aimed to explore the potential degradation of PBAT by probiotics. We screened 47 kinds of safety microbes for PBAT degradation, five probiotics showed positive degradation effects on PBAT. Among these, Lactobacillus paracasei T1–9 exhibited superior ability to degrade PBAT, achieving the highest percentage of weight loss at 1.77 ± 0.08 %, along with highly efficient growth in liquid culture. The biodegradability of PBAT was evaluated by using a multifaceted approach encompassing techniques including SEM, FTIR, XPS, and LC-MS. To improve the degradation efficiency, various factors (pH, the addition of gelatin and carbon source) were investigated. The additional gelatin improved the degradation of PBAT at a 3.43 ± 0.1 % weight loss. As the carbon source in medium, 1, 4-butanediol contributed the highest biodegradation effect compared to the other two monomers of PBAT. Interestingly, the supernatants of T1–9 incubated with PBAT displayed the highest lipase activity with 3.99 ± 0.03 U/mL. In conclusion, the probiotic T1–9 processed excellent capabilities in degrading PBAT, with the primary enzyme hypothesized to belong to the lipase group.