Discovery of plastic-degrading microbial strains isolated from the alpine and Arctic terrestrial plastisphere

Abstract

Increasing plastic production and the release of some plastic in to the environment highlight the need for circular plastic economy. Microorganisms have a great potential to enable a more sustainable plastic economy by biodegradation and enzymatic recycling of polymers. Temperature is a crucial parameter affecting biodegradation rates, but so far microbial plastic degradation has mostly been studied at temperatures above 20°C. Here, we isolated 34 cold-adapted microbial strains from the plastisphere using plastics buried in alpine and Arctic soils during laboratory incubations as well as plastics collected directly from Arctic terrestrial environments. We tested their ability to degrade, at 15°C, conventional polyethylene (PE) and the biodegradable plastics polyester-polyurethane (PUR; Impranil®); ecovio® and BI-OPL, two commercial plastic films made of polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA); pure PBAT; and pure PLA. Agar clearing tests indicated that 19 strains had the ability to degrade the dispersed PUR. Weight-loss analysis showed degradation of the polyester plastic films ecovio® and BI-OPL by 12 and 5 strains, respectively, whereas no strain was able to break down PE. NMR analysis revealed significant mass reduction of the PBAT and PLA components in the biodegradable plastic films by 8 and 7 strains, respectively. Co-hydrolysis experiments with a polymer-embedded fluorogenic probe revealed the potential of many strains to depolymerize PBAT. Neodevriesia and Lachnellula strains were able to degrade all the tested biodegradable plastic materials, making these strains especially promising for future applications. Further, the composition of the culturing medium strongly affected the microbial plastic degradation, with different strains having different optimal conditions. In our study we discovered many novel microbial taxa with the ability to break down biodegradable plastic films, dispersed PUR, and PBAT, providing a strong foundation to underline the role of biodegradable polymers in a circular plastic economy.

Proteomic examination of polyester‐polyurethane degradation by Streptomyces sp. PU10: Diverting polyurethane intermediates to secondary metabolite production

“…Nevertheless, based on the phenotypic screening results, they proved to be interesting candidates for PU degradation. Streptomyces strains have been previously reported to degrade Impranil in plate assays (Rüthi et al., 2023 ), but no in‐depth study on Streptomyces PU degradation was performed. Recent studies have reported fungal strains capable of reaching high levels of the same Impranil degradation, such as Embarria clematidis that could degrade 88.8% of 1% (v/v) Impranil after 2 weeks of incubation (Khruengsai et al., 2022 ) while Cladosporium strains could degrade 80% and 94.4% in 3 days (Liu, Ahmad, et al., 2023 ; Zhang et al., 2022 ).…”

Novel functional insights into the microbiome inhabiting marine plastic debris: critical considerations to counteract the challenges of thin biofilms using multi-omics and comparative metaproteomics

“…In doing so, we have identified several areas where the use of this approach in the future could advance marine plastisphere research: Firstly, in the assessment of temperature and sunlight (in addition to other environmental factors) as key factors regulating protein expression and community metabolism to define the trophic status of the plastisphere as a feature of location. Although still an emerging research topic, this appears to play a pivotal role in the presence of hydrocarbonoclastic lineages [ 20 , 85 , 86 ], driving the potential for biodegradation within the plastisphere, with the success of bioremediation potentially improved through increased focus on cold-adapted metabolisms [ 54 , 87 ]. Secondly, by improving the overall functional representation of the marine plastisphere, the sensitivity of techniques such as comparative metaproteomics can be continually improved through the development of specific databases which capture the diversity of peptide and protein sequences truly present in this environment [ 66 ].…”

A comparative approach to confirm antibiotic-resistant microbes in the cryosphere

“…Ice and snow samples were processed the same way, except for an initial melting step at 4°C before plating. R2A agar was chosen due to the suitability of cryospheric organisms to grow best on oligotrophic media ( Rüthi et al, 2023 ). Morphological different colonies from all samples were described, transferred into 7 mL of lysogeny broth (LB-media) with a sterile loop, and incubated for 7 days at the respective temperature.…”