Active microbial communities during biodegradation of biodegradable plastics by mesophilic and thermophilic anaerobic digestion

Biodegradable plastics, if they are not properly managed at their end-of-life, can have the same hazardous environmental consequences as conventional plastics. This study investigates the treatment of the main biode-gradable plastics under mesophilic and thermophilic anaerobic digestion using biochemical methane potential test and the microorganisms involved in the process using amplicon sequencing of the 16 S rRNA. Here we showed that, only PHB and TPS undergone important and rapid biodegradation under mesophilic condition (38 degrees C). By contrast, PCL and PLA exhibited very low biodegradation rate as 500 days were required to reach the ultimate methane yield. Little or no degradation occurred for PBAT and PBS at 38 degrees C. Under thermophilic conditions (58 degrees C), TPS, PHB, and PLA reached high levels of biodegradation in a relatively short period (< 100 d). While PBS, PBAT, and PCL could not be converted into methane at 58 degrees C. PHB degraders (Enterobacter and Cupriavidus) and lactate-utilizing bacteria (Moorella and Tepidimicrobium) appeared to play an important role in the PHB and PLA degradation, respectively. This work not only provides crucial data on the anaerobic digestion of the main biodegradable plastics but also enriches the understanding of the microorganisms involved in this process, which are of great importance for future development of the treatment of biodegradable plastics in anaerobic digestion systems.