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Zeng B, Fu Y, Ye J, Yang P, Cui S, Qiu W, Li Y, Wu T, Zhang H, Wang Y, Du G, Liu S. Ancestral sequence reconstruction of the prokaryotic three-domain laccases for efficiently degrading polyethylene. JOURNAL OF HAZARDOUS MATERIALS 2024; 476:135012. [PMID: 38944993 DOI: 10.1016/j.jhazmat.2024.135012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 06/08/2024] [Accepted: 06/22/2024] [Indexed: 07/02/2024]
Abstract
Biodegradation of polyethylene (PE) plastics is environmentally friendly. To obtain the laccases that can efficiently degrade PE plastics, we generated 9 ancestral laccases from 23 bacterial three-domain laccases through ancestral sequence reconstruction. The optimal temperatures of the ancestral laccases were between 60 °C-80 °C, while their optimal pHs were at 3.0 or 4.0. Without substrate pretreatment and mediator addition, all the ancestral laccases can degrade low-density polyethylene (LDPE) films at pH 7.0 and 60 °C. Among them, Anc52, which shared low sequence identity (18 %-41.7 %) with the reported PE-degrading laccases, was the most effective for LDPE degradation. After the catalytic reactions at 90 °C for 14 h, Anc52 (0.2 mg/mL) induced clear wrinkles and deep pits on the PE film surface detected by scanning electron microscope, and its carbonyl and hydroxyl indices reached 2.08 and 2.42, respectively. Then, we identified the residues 203 and 288 critical for PE degradation through site-directed mutation on Anc52. Moreover, Anc52 be activated by heat treatment (60 °C and 90 °C) at pH 7.0, which gave it a high catalytic efficiency (kcat/Km= 191.73 mM-1·s-1) and thermal stability (half-life at 70 °C = 13.70 h). The ancestral laccases obtained here could be good candidates for PE biodegradation.
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Affiliation(s)
- Bo Zeng
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Yishan Fu
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jiacai Ye
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Penghui Yang
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Shixiu Cui
- JiaXing Institute of Future Food, Jiaxing, Zhejiang 314000, China
| | - Wenxuan Qiu
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Yangyang Li
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Taoxu Wu
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Haiyun Zhang
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Yachan Wang
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Guocheng Du
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China.
| | - Song Liu
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China.
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Jendrossek D. Polyethylene and Related Hydrocarbon Polymers ("Plastics") Are not Biodegradable. N Biotechnol 2024:S1871-6784(24)00537-5. [PMID: 39182829 DOI: 10.1016/j.nbt.2024.08.503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 08/14/2024] [Accepted: 08/19/2024] [Indexed: 08/27/2024]
Abstract
Research on the biodegradation of polyethylene (PE), polystyrene (PS) and related polymers has become popular and the number of publications on this topic is rapidly increasing. However, there is no convincing evidence that the frequently claimed biodegradability of these so-called "plastics" really exists. Rather, a diffuse definition of the term "biodegradability" has led to the publication of reports showing either marginal weight losses of hydrocarbon polymers by the action of isolated bacterial strains or mechanical disintegration and polymer surface modification in case of hydrocarbon polymer-consuming insect larvae. Most of the data can be alternatively explained by the utilization of polymer impurities/additives, by the utilization of low molecular weight oligomers, and/or by physical fragmentation and subsequent loss of small fragments. Evidence for a (partial) biotic and/or abiotic oxidation of the amorphous polymer fraction and of surface-exposed hydrocarbon side chains is not sufficient to claim that PE is biodegradable. To the best of my knowledge, no report has been so far published in which substantial biodegradation and mineralization of PE or related (long chain length) hydrocarbon polymers to carbon dioxide has been convincingly demonstrated by the determination of the fate of carbon atoms in isotope-labeled polymers. It is disappointing that publications with a critical view on biodegradation of hydrocarbon polymers are not cited in most of these reports. The possibility should be considered that the rapidly expanding research field of hydrocarbon polymer biodegradation is chasing rainbows.
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Lee YM, Choi KM, Mun SH, Yoo JW, Jung JH. Gut microbiota composition of the isopod Ligia in South Korea exposed to expanded polystyrene pollution. PLoS One 2024; 19:e0308246. [PMID: 39110709 PMCID: PMC11305568 DOI: 10.1371/journal.pone.0308246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Accepted: 07/20/2024] [Indexed: 08/10/2024] Open
Abstract
Plastics pose a considerable challenge to aquatic ecosystems because of their increasing global usage and non-biodegradable properties. Coastal plastic debris can persist in ecosystems; however, its effects on resident organisms remain unclear. A metagenomic analysis of the isopoda Ligia, collected from clean (Nae-do, ND) and plastic-contaminated sites (Maemul-do, MD) in South Korea, was conducted to clarify the effects of microplastic contamination on the gut microbiota. Ligia gut microbiota's total operational taxonomic units were higher in ND than in MD. Alpha diversity did not differ significantly between the two Ligia gut microbial communities collected from ND and MD, although richness (Observed species) was lower in MD than in ND. Proteobacteria (67.47%, ND; 57.30%, MD) and Bacteroidetes (13.63%, ND; 20.76%, MD) were the most abundant phyla found at both sites. Significant different genera in Ligia from EPS-polluted sites were observed. Functional gene analysis revealed that 19 plastic degradation-related genes, including those encoding hydrogenase, esterase, and carboxylesterase, were present in the gut microbes of Ligia from MD, indicating the potential role of the Ligia gut microbiota in plastic degradation. This study provides the first comparative field evidence of the gut microbiota dynamics of plastic detritus consumers in marine ecosystems.
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Affiliation(s)
- Young-Mi Lee
- Department of Biotechnology, College of Convergence Engineering, Sangmyung University, Seoul, Republic of Korea
| | - Kwang-Min Choi
- Risk Assessment Research Center, Korea Institute of Ocean Science and Technology, Geoje, Republic of Korea
| | - Seong Hee Mun
- Risk Assessment Research Center, Korea Institute of Ocean Science and Technology, Geoje, Republic of Korea
| | - Je-Won Yoo
- Department of Biotechnology, College of Convergence Engineering, Sangmyung University, Seoul, Republic of Korea
| | - Jee-Hyun Jung
- Risk Assessment Research Center, Korea Institute of Ocean Science and Technology, Geoje, Republic of Korea
- Department of Marine Environmental Science, Korea University of Science and Technology, Daejeon, Republic of Korea
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Han H, Song P, Jiang Y, Fan J, Khan A, Liu P, Mašek O, Li X. Biochar immobilized hydrolase degrades PET microplastics and alleviates the disturbance of soil microbial function via modulating nitrogen and phosphorus cycles. JOURNAL OF HAZARDOUS MATERIALS 2024; 474:134838. [PMID: 38850944 DOI: 10.1016/j.jhazmat.2024.134838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 05/07/2024] [Accepted: 06/04/2024] [Indexed: 06/10/2024]
Abstract
Microplastics (MPs) pose an emerging threat to soil ecological function, yet effective solutions remain limited. This study introduces a novel approach using magnetic biochar immobilized PET hydrolase (MB-LCC-FDS) to degrade soil polyethylene terephthalate microplastics (PET-MPs). MB-LCC-FDS exhibited a 1.68-fold increase in relative activity in aquatic solutions and maintained 58.5 % residual activity after five consecutive cycles. Soil microcosm experiment amended with MB-LCC-FDS observed a 29.6 % weight loss of PET-MPs, converting PET into mono(2-hydroxyethyl) terephthalate (MHET). The generated MHET can subsequently be metabolized by soil microbiota to release terephthalic acid. The introduction of MB-LCC-FDS shifted the functional composition of soil microbiota, increasing the relative abundances of Microbacteriaceae and Skermanella while reducing Arthobacter and Vicinamibacteraceae. Metagenomic analysis revealed that MB-LCC-FDS enhanced nitrogen fixation, P-uptake and transport, and organic-P mineralization in PET-MPs contaminated soil, while weakening the denitrification and nitrification. Structural equation model indicated that changes in soil total carbon and Simpson index, induced by MB-LCC-FDS, were the driving factors for soil carbon and nitrogen transformation. Overall, this study highlights the synergistic role of magnetic biochar-immobilized PET hydrolase and soil microbiota in degrading soil PET-MPs, and enhances our understanding of the microbiome and functional gene responses to PET-MPs and MB-LCC-FDS in soil systems.
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Affiliation(s)
- Huawen Han
- Centre for Grassland Microbiome, State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu Province 730000, China
| | - Peizhi Song
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China; State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yuchao Jiang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China
| | - Jingwen Fan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China
| | - Aman Khan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China; College of Life Science, Northeast Forestry University, Harbin 150040, China
| | - Pu Liu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China
| | - Ondřej Mašek
- UK Biochar Research Centre, School of GeoSciences, University of Edinburgh, Crew Building, King's Buildings, Edinburgh EH9 3FF, United Kingdom.
| | - Xiangkai Li
- Centre for Grassland Microbiome, State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu Province 730000, China; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China.
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M SF, Narayanan R. Enterobacter cloacae-mediated polymer biodegradation: in-silico analysis predicts broad spectrum degradation potential by Alkane monooxygenase. Biodegradation 2024:10.1007/s10532-024-10091-4. [PMID: 39001975 DOI: 10.1007/s10532-024-10091-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 07/03/2024] [Indexed: 07/15/2024]
Abstract
Plastic pollution poses a significant environmental challenge. In this study, the strain Enterobacter cloacae O5-E, a bacterium displaying polyethylene-degrading capabilities was isolated. Over a span of 30 days, analytical techniques including x-ray diffractometry, scanning electron microscopy, optical profilometry, hardness testing and mass spectrometric analysis were employed to examine alterations in the polymer. Results revealed an 11.48% reduction in crystallinity, a 50% decrease in hardness, and a substantial 25-fold increase in surface roughness resulting from the pits and cracks introduced in the polymer by the isolate. Additionally, the presence of degradational by-products revealed via gas chromatography ascertains the steady progression of degradation. Further, recognizing the pivotal role of alkane monooxygenase in plastic degradation, the study expanded to detect this enzyme in the isolate molecularly. Molecular docking studies were conducted to assess the enzyme's affinity with various polymers, demonstrating notable binding capability with most polymers, especially with polyurethane (- 5.47 kcal/mol). These findings highlight the biodegradation potential of Enterobacter cloacae O5-E and the crucial involvement of alkane monooxygenase in the initial steps of the degradation process, offering a promising avenue to address the global plastic pollution crisis.
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Affiliation(s)
- Shafana Farveen M
- Department of Genetic Engineering, School of Bioengineering and Faculty of Engineering and Technology, College of Engineering & Technology (CET), SRM Institute of Science and Technology, Kattankulathur, Kanchipuram, Chennai, Tamil Nadu, 603203, India
| | - Rajnish Narayanan
- Department of Genetic Engineering, School of Bioengineering and Faculty of Engineering and Technology, College of Engineering & Technology (CET), SRM Institute of Science and Technology, Kattankulathur, Kanchipuram, Chennai, Tamil Nadu, 603203, India.
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6
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Dar MA, Xie R, Zabed HM, Pawar KD, Dhole NP, Sun J. Current paradigms and future challenges in harnessing gut bacterial symbionts of insects for biodegradation of plastic wastes. INSECT SCIENCE 2024. [PMID: 38990171 DOI: 10.1111/1744-7917.13417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/30/2024] [Accepted: 05/22/2024] [Indexed: 07/12/2024]
Abstract
The ubiquitous incorporation of plastics into daily life, coupled with inefficient recycling practices, has resulted in the accumulation of millions of metric tons of plastic waste, that poses a serious threat to the Earth's sustainability. Plastic pollution, a global problem, disrupts the ecological balance and endangers various life forms. Efforts to combat plastic pollution are underway, with a promising avenue being biological degradation facilitated by certain insects and their symbiotic gut microorganisms, particularly bacteria. This review consolidates existing knowledge on plastic degradation by insects and their influence on gut microbiota. Additionally, it delves into the potential mechanisms employed by insects in symbiosis with gut bacteria, exploring the bioconversion of waste plastics into value-added biodegradable polymers through mineralization. These insights hold significant promise for the bio-upcycling of plastic waste, opening new horizons for future biomanufacturing of high-value chemicals from plastic-derived compounds. Finally, we weigh the pros and cons of future research endeavors related to the bioprospection of plastic-degrading bacteria from underexplored insect species. We also underscore the importance of bioengineering depolymerases with novel characteristics, aiming for their application in the remediation and valorization of waste plastics.
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Affiliation(s)
- Mudasir A Dar
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
- Department of Zoology, Savitribai Phule Pune University, Ganeshkhind, Pune, Maharashtra, India
| | - Rongrong Xie
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
| | - Hossain M Zabed
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Kiran D Pawar
- School of Nanoscience and Biotechnology, Shivaji University, Vidyanagar, Kolhapur, Maharashtra, India
| | - Neeraja P Dhole
- Department of Zoology, Savitribai Phule Pune University, Ganeshkhind, Pune, Maharashtra, India
| | - Jianzhong Sun
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
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7
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Satta A, Ghiotto G, Santinello D, Giangeri G, Bergantino E, Modesti M, Raga R, Treu L, Campanaro S, Zampieri G. Synergistic functional activity of a landfill microbial consortium in a microplastic-enriched environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 947:174696. [PMID: 38997032 DOI: 10.1016/j.scitotenv.2024.174696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 07/05/2024] [Accepted: 07/09/2024] [Indexed: 07/14/2024]
Abstract
Plastic pollution of the soil is a global issue of increasing concern, with far-reaching impact on the environment and human health. To fully understand the medium- and long-term impact of plastic dispersal in the environment, it is necessary to define its interaction with the residing microbial communities and the biochemical routes of its degradation and metabolization. However, despite recent attention on this problem, research has largely focussed on microbial functional potential, failing to clearly identify collective adaptation strategies of these communities. Our study combines genome-centric metagenomics and metatranscriptomics to characterise soil microbial communities adapting to high polyethylene and polyethylene terephthalate concentration. The microbiota were sampled from a landfill subject to decades-old plastic contamination and enriched through prolonged cultivation using these microplastics as the only carbon source. This approach aimed to select the microorganisms that best adapt to these specific substrates. As a result, we obtained simplified communities where multiple plastic metabolization pathways are widespread across abundant and rare microbial taxa. Major differences were found in terms of expression, which on average was higher in planktonic microbes than those firmly adhered to plastic, indicating complementary metabolic roles in potential microplastic assimilation. Moreover, metatranscriptomic patterns indicate a high transcriptional level of numerous genes in emerging taxa characterised by a marked accumulation of genomic variants, supporting the hypothesis that plastic metabolization requires an extensive rewiring in energy metabolism and thus provides a strong selective pressure. Altogether, our results provide an improved characterisation of the impact of microplastics derived from common plastics types on terrestrial microbial communities and suggest biotic responses investing contaminated sites as well as potential biotechnological targets for cooperative plastic upcycling.
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Affiliation(s)
- Alessandro Satta
- Department of Biology, University of Padua, via U. Bassi 58/b, 35131 Padova, Italy
| | - Gabriele Ghiotto
- Department of Biology, University of Padua, via U. Bassi 58/b, 35131 Padova, Italy
| | - Davide Santinello
- Department of Biology, University of Padua, via U. Bassi 58/b, 35131 Padova, Italy
| | - Ginevra Giangeri
- Department of Biology, University of Padua, via U. Bassi 58/b, 35131 Padova, Italy; Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, 227, 220, 2800 Kgs. Lyngby, Denmark
| | | | - Michele Modesti
- Department of Industrial Engineering, University of Padua, Via Gradenigo, 6/a, 35131 Padova, Italy
| | - Roberto Raga
- Department of Civil, Environmental and Architectural Engineering, University of Padua, via Marzolo 9, 35131 Padova, Italy
| | - Laura Treu
- Department of Biology, University of Padua, via U. Bassi 58/b, 35131 Padova, Italy.
| | - Stefano Campanaro
- Department of Biology, University of Padua, via U. Bassi 58/b, 35131 Padova, Italy
| | - Guido Zampieri
- Department of Biology, University of Padua, via U. Bassi 58/b, 35131 Padova, Italy
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8
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Rong Z, Xu XW, Wu YH. Biodegradation of low-density polyethylene film by two bacteria isolated from plastic debris in coastal beach. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 278:116445. [PMID: 38733804 DOI: 10.1016/j.ecoenv.2024.116445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 02/27/2024] [Accepted: 05/05/2024] [Indexed: 05/13/2024]
Abstract
Low-density polyethylene (LDPE) conduces massive environmental accumulation due to its high production and recalcitrance to environment. In this study, We successfully enriched and isolated two strains, Nitratireductor sp. Z-1 and Gordonia sp. Z-2, from coastal plastic debris capable of degrading LDPE film. After a 30-day incubation at 30 ℃, strains Z-1 and Z-2 decreased the weight of branched-LDPE (BLDPE) film by 2.59 % and 10.27 % respectively. Furthermore, high temperature gel permeation chromatography (HT-GPC) analysis revealed molecular weight reductions of 7.69 % (Z-1) and 23.22 % (Z-2) in the BLDPE film. Scanning electron microscope (SEM) image showed the presence of microbial colonization and perforations on the film's surface. Fourier transform infrared spectroscopy (FTIR) analysis indicated novel functional groups, such as carbonyl and carbon-carbon double bonds in LDPE films. During LDPE degradation, both strains produced extracellular reactive oxygen species (ROS). GC-MS analysis revealed the degradation products included short-chain alkanes, alkanols, fatty acids, and esters. Genomic analysis identified numerous extracellular enzymes potentially involved in LDPE chain scission. A model was proposed suggesting a coordinated role between ROS and extracellular enzymes in the biodegradation of LDPE. This indicates strains Z-1 and Z-2 can degrade LDPE, providing a basis for deeper exploration of biodegradation mechanisms.
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Affiliation(s)
- Zhen Rong
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, PR China; School of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Xue-Wei Xu
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, PR China; School of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Yue-Hong Wu
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, PR China; School of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, PR China.
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9
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Chen Y, Niu L, Li Y, Wang Y, Shen J, Zhang W, Wang L. Distribution characteristics and microbial synergistic degradation potential of polyethylene and polypropylene in freshwater estuarine sediments. JOURNAL OF HAZARDOUS MATERIALS 2024; 471:134328. [PMID: 38643575 DOI: 10.1016/j.jhazmat.2024.134328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/10/2024] [Accepted: 04/15/2024] [Indexed: 04/23/2024]
Abstract
The microbial degradation of polyethylene (PE) and polypropylene (PP) resins in rivers and lakes has emerged as a crucial issue in the management of microplastics. This study revealed that as the flow rate decreased longitudinally, ammonia nitrogen (NH4+-N), heavy fraction of organic carbon (HFOC), and small-size microplastics (< 1 mm) gradually accumulated in the deep and downstream estuarine sediments. Based on their surface morphology and carbonyl index, these sediments were identified as the potential hot zone for PE/PP degradation. Within the identified hot zone, concentrations of PE/PP-degrading genes, enzymes, and bacteria were significantly elevated compared to other zones, exhibiting strong intercorrelations. Analysis of niche differences revealed that the accumulation of NH4+-N and HFOC in the hot zone facilitated the synergistic coexistence of key bacteria responsible for PE/PP degradation within biofilms. The findings of this study offer a novel insight and comprehensive understanding of the distribution characteristics and synergistic degradation potential of PE/PP in natural freshwater environments.
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Affiliation(s)
- Yamei Chen
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China
| | - Lihua Niu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Yi Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Yingjie Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China
| | - Jiayan Shen
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China
| | - Wenlong Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China
| | - Linqiong Wang
- College of Oceanography, Hohai University, Nanjing 210098, PR China
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10
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Li Y, Xu G, Yu Y. Freeze-thaw aged polyethylene and polypropylene microplastics alter enzyme activity and microbial community composition in soil. JOURNAL OF HAZARDOUS MATERIALS 2024; 470:134249. [PMID: 38603909 DOI: 10.1016/j.jhazmat.2024.134249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/26/2024] [Accepted: 04/08/2024] [Indexed: 04/13/2024]
Abstract
In cold regions, microplastics (MPs) in the soil undergo freeze-thaw (FT) aging process. Little is known about how FT aged MPs influence soil physico-chemical properties and microbial communities. Here, two environmentally relevant concentrations (50 and 500 mg/kg) of 50 and 500 µm polyethylene (PE) and polypropylene (PP) MPs treated soils were subjected to 45-day FT cycles (FTCs). Results showed that MPs experienced surface morphology, hydrophobicity and crystallinity alterations after FTCs. After 45-day FTCs, the soil urease (SUE) activity in control (MPs-free group that underwent FTCs) was 33.49 U/g. SUE activity in 50 µm PE group was reduced by 19.66 %, while increased by 21.16 % and 37.73 % in 500 µm PE and PP groups compared to control. The highest Shannon index was found in 50 µm PP-MPs group at 50 mg/kg, 2.26 % higher than control (7.09). Compared to control (average weighted degree=8.024), all aged MPs increased the complexity of network (0.19-1.43 %). Bacterial biomarkers of aged PP-MPs were associated with pollutant degradation. Aged PP-MPs affected genetic information, cellular processes, and disrupted the biosynthesis of metabolites. This study provides new insights into the potential hazards of MPs after FTCs on soil ecosystem in cold regions.
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Affiliation(s)
- Yanjun Li
- Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guanghui Xu
- Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
| | - Yong Yu
- Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
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Du T, Qian L, Shao S, Xing T, Li T, Wu L. Comparison of sulfide-induced transformation of biodegradable and conventional microplastics: Mechanism and environmental fate. WATER RESEARCH 2024; 253:121295. [PMID: 38354663 DOI: 10.1016/j.watres.2024.121295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/31/2024] [Accepted: 02/08/2024] [Indexed: 02/16/2024]
Abstract
Biodegradable plastics have been massively produced and used as potential substitutes for conventional plastics, resulting in their inevitable entry into the environment and generation of biodegradable microplastics (MPs). The sulfidation transformation of MPs is an important process for their transformation in anoxic environments (e.g., sediments, anaerobic activated sludges) that can alter their environmental effects and risks. However, how sulfides induce the transformation of biodegradable MPs and whether they are similar to conventional MPs remains unknown. In the present study, we compared the transformation and mechanism of conventional polyethylene (PE) MPs and biodegradable poly(butylene adipate-co-terephthalate) (PBAT) MPs during sulfidation. The results demonstrated that sulfidation resulted in oxidation of PE MPs, whereas PBAT MPs underwent reduction and had higher physical damage, as evidenced by fragmentation, chain scission and organic compound release. Besides, reactive oxygen species and sulfide species played important roles in the sulfidation of PE and PBAT MPs, respectively. The presence of ester groups in PBAT MPs led to their hydrolysis, causing chain scission and further reduction. Furthermore, sulfidation caused a higher degree of adsorption and toxicity alterations in PBAT MPs than in PE MPs. This work uncovers critical abiotic transformation behaviors of biodegradable microplastics and highlights the necessity of considering microplastic structural features to accurately predict microplastic occurrence.
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Affiliation(s)
- Tingting Du
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
| | - Liwen Qian
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Song Shao
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Tianran Xing
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Tong Li
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
| | - Lijun Wu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
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