Characteristics of Tepidimicrobium xylanilyticum as a lactate-utilising bacterium in polylactic acid decomposition during thermophilic anaerobic digestion
2020
Tseng, Hou-Chia | Fujimoto, Naoshi | Ohnishi, Akihiro
Global production of polylactic acid (PLA) is projected to increase to approximately 0.33 million tons by 2024. Therefore, better understanding of the biological mechanism of PLA decomposition is essential for waste management. This study aimed to evaluate the effect of lactate accumulation on PLA depolymerisation and identify the lactate-utilising bacteria (LUB) during thermophilic anaerobic digestion (TAD). Evaluation of PLA decomposability and characterisation of the isolate cultivated from PLA-treated TAD were conducted using batch testing. In high lactate concentrations, 34%–44% reduction of physicochemical PLA depolymerisation was observed, suggesting that LUB were important lactate scavengers for rapid PLA depolymerisation process. The isolate EN5CB1 was identified as Tepidimicrobium xylanilyticum; however, several of its characteristics differed from that of the PML14ᵀ. Strain EN5CB1 demonstrated high lactate consumption and H₂, CO₂, and acetate productivity. These findings provide new insights into the role of T. xylanilyticum in PLA treatment through TAD.
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