Bioaugmentation with a defined bacterial consortium: A key to degrade high molecular weight polylactic acid during traditional composting

Avnish Nitin Mistry; Boonlue Kachenchart; Onruthai Pinyakong; Wanchai Assavalapsakul; Somrudee Meprasert Jitpraphai; Anongnat Somwangthanaroj; Ekawan Luepromchai

doi:10.1016/j.biortech.2022.128237

Bioaugmentation with a defined bacterial consortium: A key to degrade high molecular weight polylactic acid during traditional composting

Bioresour Technol. 2023 Jan:367:128237. doi: 10.1016/j.biortech.2022.128237. Epub 2022 Nov 1.

Authors

Avnish Nitin Mistry¹, Boonlue Kachenchart², Onruthai Pinyakong³, Wanchai Assavalapsakul⁴, Somrudee Meprasert Jitpraphai⁵, Anongnat Somwangthanaroj⁶, Ekawan Luepromchai⁷

Affiliations

¹ International Program in Hazardous Substance and Environmental Management (IP-HSM), Graduate School, Chulalongkorn University, Bangkok, Thailand; Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Bangkok, Thailand.
² Faculty of Environment and Resource Studies, Mahidol University, Nakhon Pathom, Thailand.
³ Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Bangkok, Thailand; Center of Excellence in Microbial Technology for Marine Pollution Treatment (MiTMaPT), Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
⁴ Center of Excellence in Microbial Technology for Marine Pollution Treatment (MiTMaPT), Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
⁵ Center of Excellence in Microbial Technology for Marine Pollution Treatment (MiTMaPT), Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand; Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
⁶ Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand.
⁷ Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Bangkok, Thailand; Center of Excellence in Microbial Technology for Marine Pollution Treatment (MiTMaPT), Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand. Electronic address: ekawan.l@chula.ac.th.

PMID: 36332866
DOI: 10.1016/j.biortech.2022.128237

Abstract

Polylactic acid (PLA) is commercialized as a compostable bio-thermoplastic. PLA degrades under industrial composting conditions where elevated temperatures are maintained for a long timeframe. However, these conditions cannot be achieved in a non-industrial compost pile. Therefore, this study aims to degrade high molecular weight PLA films by adding a PLA-degrading bacterial consortium (EAc) comprised of Nocardioides zeae EA12, Stenotrophomonas pavanii EA33, Gordonia desulfuricans EA63, and Chitinophaga jiangningensis EA02 during traditional composting. With EAc-bioaugmentation, PLA films (5-30% w/w) had complete disintegration (35 d), 77-82% molecular weight reduction (16 d), and higher CO₂ liberation and mineralization than non-bioaugmented composting. Bacterial community analyses showed that EAc-bioaugmentation increased the relative abundance of Schlegelella, a known polymer degrader, and interacted positively with beneficial indigenous microbes like Bacillus, Schlegelella and Thermopolyspora. The bioaugmentation also decreased compost phytotoxicity. Hence, consortium EAc shows potential in PLA-waste treatment applications, such as backyard and small-scale composting.

Keywords: Bacterial community; Bacterial interaction; Bio-thermoplastic; Biodegradation; Respirometer.

MeSH terms

Bacteria / metabolism
Biodegradation, Environmental
Composting*
Molecular Weight
Polyesters / metabolism
Soil

Substances

poly(lactide)
Polyesters
Soil