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Microbiology Spectrum Aug 2023Over half of the world's plastic waste is landfilled, where it is estimated to take hundreds of years to degrade. Given the continued use and disposal of plastic...
Over half of the world's plastic waste is landfilled, where it is estimated to take hundreds of years to degrade. Given the continued use and disposal of plastic products, it is vital that we develop fast and effective ways to utilize plastic waste. Here, we explore the potential of tandem chemical and biological processing to process various plastics quickly and effectively. Four samples of compost or sediment were used to set up enrichment cultures grown on mixtures of compounds, including disodium terephthalate and terephthalic acid (monomers of polyethylene terephthalate), compounds derived from the chemical deconstruction of polycarbonate, and pyrolysis oil derived from high-density polyethylene plastics. Established enrichment communities were also grown on individual substrates to investigate the substrate preferences of different taxa. Biomass harvested from the cultures was characterized using 16S rRNA gene amplicon sequencing and shotgun metagenomic sequencing. These data reveal low-diversity microbial communities structured by differences in culture inoculum, culture substrate source plastic type, and time. Microbial populations from the classes , , , and were significantly enriched when grown on substrates derived from high-density polyethylene and polycarbonate. The metagenomic data contain abundant aromatic and aliphatic hydrocarbon degradation genes relevant to the biodegradation of deconstructed plastic substrates used here. We show that microbial populations from diverse environments are capable of growth on substrates derived from the chemical deconstruction or pyrolysis of multiple plastic types and that paired chemical and biological processing of plastics should be further developed for industrial applications to manage plastic waste. The durability and impermeable nature of plastics have made them a popular material for numerous applications, but these same qualities make plastics difficult to dispose of, resulting in massive amounts of accumulated plastic waste in landfills and the natural environment. Since plastic use and disposal are projected to increase in the future, novel methods to effectively break down and dispose of current and future plastic waste are desperately needed. We show that the products of chemical deconstruction or pyrolysis of plastic can successfully sustain the growth of low-diversity microbial communities. These communities were enriched from multiple environmental sources and are capable of degrading complex xenobiotic carbon compounds. This study demonstrates that tandem chemical and biological processing can be used to degrade multiple types of plastics over a relatively short period of time and may be a future avenue for the mitigation of rapidly accumulating plastic waste.
Topics: Plastics; Polyethylene; RNA, Ribosomal, 16S; Polyethylene Terephthalates; Bacteria
PubMed: 37260392
DOI: 10.1128/spectrum.00362-23 -
Ying Yong Sheng Tai Xue Bao = the... Nov 2023Environmental endocrine disrupting chemicals (EDCs), known as environmental hormones, are exogenous chemicals that can disrupt hormone levels and cause dysfunction of... (Review)
Review
Environmental endocrine disrupting chemicals (EDCs), known as environmental hormones, are exogenous chemicals that can disrupt hormone levels and cause dysfunction of the secretory system in humans and animals. Plasticizers, which are widely used EDCs, are commonly used to enhance the flexibility of plastic products. As plastics age and wear, however, they can leach into the environment and enter the bodies of animals through various pathways such as the digestive tract and skin. They can lead to estrogen-like effects and have substantial reproductive toxicity. Residual plasticizer concentrations in the environment are typically low. Unlike high doses that induce acute damage to the reproductive system, low doses of plasticizers do not cause macroscopic harm and thus its reproductive toxicity is often overlooked for extended periods. An increasing number of studies conducted on humans and mice in recent years have demonstrated that low doses of plasticizers can induce reproductive toxicity by interfering with maternal behavior. Prenatal exposure to plasticizers can result in abnormal postnatal maternal behavior. Female offspring also exhibit significantly low maternal care, lactation, and other behaviors in adulthood, which may persist for multiple generations, significantly disrupting the animal breeding process and impacting the health and well-being of newborn pups. The underlying mechanisms have not been systematically summarized. The risk of continuous exposure to low-dose plasticizers in humans and animals has increased due to the extensive utilization of plastic and rubber products in modern production and lifestyle patterns. It is thus crucial to conduct a systematic review on the effects of low-dose plasticizers on maternal behavior. We reviewed the research progress on the disruptive effects of plasticizers on animals' maternal behavior and concluded that these effects are primarily caused by inducing oxidative stress damage and DNA methylation reprogramming in the hypothalamic-pituitary-ovarian axis, as well as disrupting the balance of the thyroid system and causing intestinal microbial disorders. It would offer a novel perspective for future studies about the influence of plasticizers and other environmental hormones on maternal behavior in domesticated animals.
Topics: Animals; Female; Humans; Mice; Pregnancy; Hormones; Maternal Behavior; Plasticizers; Plastics; Reproduction
PubMed: 37997427
DOI: 10.13287/j.1001-9332.202311.028 -
The Science of the Total Environment Sep 2023For the past two decades, with the increase in plastic consumption came a rise in plastic waste, with the bulk of it ending up in landfills, incinerated, recycled or... (Review)
Review
For the past two decades, with the increase in plastic consumption came a rise in plastic waste, with the bulk of it ending up in landfills, incinerated, recycled or leaking into the environment, especially in aquatic ecosystems. Plastic waste poses a significant environmental threat and a wealth issue due to its non-biodegradability and recalcitrant nature. Polyethylene (PE) remains one of the major utilized polymers in different applications amid all the other types because of its low production costs, simplistic nature prone to be modified and historically predominant researched material. Since the common methods for plastic disposal are troubled by limitations, there is a growing need for more appropriate and environment friendly methods alternatives. This study highlights several ways that can be used to assist PE (bio)degradation and mitigate its waste impact. Biodegradation (microbiological activity driven) and photodegradation (radiation driven) are the most promising for PE waste control. The shape of the material (powder, film, particles, etc.), the composition of medium, additives and pH, temperature and incubation or exposure times contribute to plastic degradation efficiency. Moreover, radiation pretreatment can enhance the biodegradability of PE, providing a promising approach to fighting plastic pollution. This paper relates the most significant results regarding PE degradation studies followed by weight loss analysis, surface morphology changes, oxidation degree (for photodegradation) and mechanical properties assessment. All combined strategies are very promising to minimize the polyethylene impact. However, there is still a long way to go through. The degradation kinetics is still low for the currently available biotic or abiotic processes, and complete mineralization is thoroughly unseen.
Topics: Polyethylene; Ecosystem; Plastics; Polymers; Biodegradation, Environmental
PubMed: 37285989
DOI: 10.1016/j.scitotenv.2023.164629 -
Environmental Pollution (Barking, Essex... Sep 2023The presence of plastic in our environment is having a massive impact on today's marine biota. Whales and dolphins are becoming sentinels of litter pollution as plastic... (Review)
Review
The presence of plastic in our environment is having a massive impact on today's marine biota. Whales and dolphins are becoming sentinels of litter pollution as plastic entanglement and ingestion affect them with unknown consequences. Although information exists about this anthropogenic interaction, the compilation of this data on metastudies is difficult due to the use of varied methodologies. A combination of our own data as well as a review of historical data was used to complete an extensive study of how cetaceans are interacting with macro and micro-litter at a global level. Here, we identify the plastic uptake by two cetacean families: Ziphiidae and Delphinidae, thus allowing for a better understanding in order to offer a global overview of their current status. Additionally, analysis was run on the plastic found in the digestive contents of stranded specimens of two Cuvier's beaked whales and fourteen striped dolphins in the Alboran Sea, in the Western Mediterranean, a hotspot for marine megafauna. Out of 623 stranded cetaceans from datasets, beaked whales displayed the highest concentration of macro, meso and microplastic in the Western Pacific Ocean. Regarding striped dolphins, Eastern Spain was the location with the highest plastic ingestion. Moreover, deep divers such as beaked whales ingested more plastic than striped dolphins which could be as a consequence of their feeding behavior or habitat. Thus, this overview provides useful information concerning conservation issues on how cetacean hotspots are highly affected by marine plastic ingestion.
Topics: Animals; Whales; Plastics; Stenella; Dolphins; Eating
PubMed: 37336348
DOI: 10.1016/j.envpol.2023.121932 -
Molecules (Basel, Switzerland) Sep 2023In recent years, there has been a growing attempt to manipulate various properties of biodegradable materials to use them as alternatives to their synthetic plastic... (Review)
Review
In recent years, there has been a growing attempt to manipulate various properties of biodegradable materials to use them as alternatives to their synthetic plastic counterparts. Alginate is a polysaccharide extracted from seaweed or soil bacteria that is considered one of the most promising materials for numerous applications. However, alginate potential for various applications is relatively limited due to brittleness, poor mechanical properties, scaling-up difficulties, and high water vapor permeability (WVP). Choosing an appropriate plasticizer can alleviate the situation by providing higher flexibility, workability, processability, and in some cases, higher hydrophobicity. This review paper discusses the main results and developments regarding the effects of various plasticizers on the properties of alginate-based films during the last decades. The plasticizers used for plasticizing alginate were classified into different categories, and their behavior under different concentrations and conditions was studied. Moreover, the drawback effects of plasticizers on the mechanical properties and WVP of the films are discussed. Finally, the role of plasticizers in the improved processing of alginate and the lack of knowledge on some aspects of plasticized alginate films is clarified, and accordingly, some recommendations for more classical studies of the plasticized alginate films in the future are offered.
PubMed: 37764413
DOI: 10.3390/molecules28186637 -
Trends in Biotechnology Mar 2024The design and study of active microbial consortia able to degrade plastics represent an exciting area of research toward the development of bio-based alternatives to...
The design and study of active microbial consortia able to degrade plastics represent an exciting area of research toward the development of bio-based alternatives to efficiently transform plastic waste. This forum article discusses concepts and mechanisms to inform emerging strategies for engineering microbiomes to transform plastics under controlled settings.
Topics: Plastics; Biodegradation, Environmental; Microbiota; Microbial Consortia
PubMed: 37845169
DOI: 10.1016/j.tibtech.2023.09.011 -
Protein Engineering, Design & Selection... Jan 2024Plastic degrading enzymes have immense potential for use in industrial applications. Protein engineering efforts over the last decade have resulted in considerable... (Review)
Review
Plastic degrading enzymes have immense potential for use in industrial applications. Protein engineering efforts over the last decade have resulted in considerable enhancement of many properties of these enzymes. Directed evolution, a protein engineering approach that mimics the natural process of evolution in a laboratory, has been particularly useful in overcoming some of the challenges of structure-based protein engineering. For example, directed evolution has been used to improve the catalytic activity and thermostability of polyethylene terephthalate (PET)-degrading enzymes, although its use for the improvement of other desirable properties, such as solvent tolerance, has been less studied. In this review, we aim to identify some of the knowledge gaps and current challenges, and highlight recent studies related to the directed evolution of plastic-degrading enzymes.
Topics: Directed Molecular Evolution; Protein Engineering; Plastics; Polyethylene Terephthalates; Enzymes
PubMed: 38713696
DOI: 10.1093/protein/gzae009 -
Environmental Research Aug 2023Environment plastic litter accumulation is a significant concern, needing urgent advancements in plastic waste management. Recent investigations into plastic... (Review)
Review
Environment plastic litter accumulation is a significant concern, needing urgent advancements in plastic waste management. Recent investigations into plastic biodegradation by bacteria and their enzymes are creating exciting unique opportunities for the development of biotechnological plastic waste treatment methods. This review summarizes information on bacterial and enzymatic biodegradation of plastic in a wide range of synthetic plastics such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyurethane (PUR), polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC). Plastic biodegradation is facilitated by Acinetobacter, Bacillus, Brevibacillus, Escherichia, Pseudomonas, Micrococcus, Streptomyces, and Rhodococcus bacteria, and enzymes such as proteases, esterases, lipases, and glycosidases. Molecular and analytical procedures used to analyze biodegradation processes are outlined, as are the obstacles in verifying plastic breakdown using these methods. Taken together, the findings of this study will contribute significantly to the construction of a library of high-efficiency bacterial isolates and consortiums and their enzymes for use in plastic biosynthesis. This information is useful to researchers investigating plastic bioremediation and a supplement to the scientific and grey literature already accessible. Finally, the review focuses on expanding the understanding of bacterial capacity to break-down plastic utilizing modern biotechnological methods, bio-nanotechnological-based materials, and their future role in resolving pollution problems.
Topics: Plastics; Microplastics; Biodegradation, Environmental; Bacteria; Polyethylene
PubMed: 37172684
DOI: 10.1016/j.envres.2023.116110 -
Environmental Science and Pollution... Nov 2023In view of the growing demand for plastic products, an enormous proportion of plastic waste causing the biological issue is produced. Plants in collaboration with their...
In view of the growing demand for plastic products, an enormous proportion of plastic waste causing the biological issue is produced. Plants in collaboration with their rhizobacteria partners are also exposed to these contaminants. The study aims to determine the rhizobacterial ability to biodegrade PET plastic. We isolated the rhizobacteria capable of degrading the PET plastic in minimal salt media using it as a sole carbon source. The three rhizospheric isolates, namely Priestia aryabhattai VT 3.12 (GenBank accession No. OK135732.1), Bacillus pseudomycoides VT 3.15 (GenBank accession No. OK135733.1), and Bacillus pumilus VT 3.16 (GenBank accession No. OK1357324.1), showed the highest degradation percentage for PET sheet and powder. The biodegradation end products post 28 days for PET sheet and 18 days of PET powder were studied by Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and scanning electron microscopy (SEM). Our results showed significant biodegradation of PET plastic, and the rate of degradation could account for over 65%. The present study proves soil rhizobacteria's potential and capabilities for efficient degradation of PET plastic occurring at the waste sites. It also implies that rhizobacteria could be beneficial in the remediation of PET waste in future applications.
Topics: Polyethylene Terephthalates; Powders; Plastics; Biodegradation, Environmental; Spectroscopy, Fourier Transform Infrared; Polyethylene
PubMed: 35460002
DOI: 10.1007/s11356-022-20324-9 -
Environmental Pollution (Barking, Essex... Feb 2024The extensive utilization and inadequate handling of plastics have resulted in severe environmental ramifications. In particular, plastics composed solely of a... (Review)
Review
The extensive utilization and inadequate handling of plastics have resulted in severe environmental ramifications. In particular, plastics composed solely of a carbon-carbon (C-C) backbone exhibit limited degradation due to the absence of hydrolyzable functional groups. Plastics with enduring longevity in the natural environment are susceptible to environmental factors and their intrinsic properties, subsequently undergoing a series of aging processes that culminate in biodegradation. This article focuses on polystyrene (PS), which constitutes 20% of total plastic waste, as a case study. Initially, the application of PS in life and the impacts it poses are introduced. Following that, the key factors influencing the aging of PS are discussed, primarily encompassing its properties (e.g., surface characteristics, additives) and environmental factors (e.g., water matrices, biofilms). Lastly, an overview of microbial degradation of PS is provided, including potential microorganisms involved in PS degradation (bacteria, fungi, algae, and insects), four processes of microbial degradation (colonization, bio-fragmentation, assimilation, and mineralization), and potential mechanisms of microbial degradation. This study provides a comprehensive understanding of the multifaceted influences affecting the aging and biodegradation mechanisms of PS, thereby contributing valuable insights for the future management of plastic pollution.
Topics: Polystyrenes; Plastics; Biodegradation, Environmental; Carbon
PubMed: 38016589
DOI: 10.1016/j.envpol.2023.123034