Methanogenic biodegradation of thermoplastic poly(vinyl alcohol) films produced by two manufacturing processes in enrichment cultures

Thermoplastic polyvinyl alcohol (TPVA) is a biodegradable polymeric plastic and is a promising alternative to traditional non-biodegradable plastics in a range of applications. However, the knowledge of anaerobic TPVA biodegradation is still limited. In this study, we evaluated the anaerobic biodegradation of two types of TPVA films manufactured using extrusion film casting and biaxial orientation methods. The results indicated that TPVA films prepared by extrusion casting were more rapidly degraded under anaerobic conditions, especially in cultures enriched from landfills than oil production water. 16S rRNA sequencing and functional prediction were performed by software PICRUSt. The results showed that members in Synergistales and Bacillales were likely responsible for secreting extracellular enzymes to depolymerize TPVA during the initial stage of the degradation process. Moreover, methanogens, such as Methanothermobacter, Methanoculleus, and Methanosarcina utilized the H2, CO2, and acetate produced from bacterial partners when degrading TPVA to generate methane. This work provides a comparative analysis and a basis for the process of anaerobic biodegradability of TPVA produced by different manufacturing processes. It is of significant importance for the future promotion of TPVA applications and the mitigation of environmental pollution.