Biodegradation Of Plastic Wastes Research Articles

Current paradigms and future challenges in harnessing gut bacterial symbionts of insects for biodegradation of plastic wastes.

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.

Biodegradation of Plastic Wastes in Soil: A Review on Testing and Evaluation Procedures

The recalcitrant behaviour of plastic creates an acute pollution on soil and aquatic biota. The plastic polymer synthesised from petroleum takes several hundred years to degrade. During excavation activities on the lands within or at the outskirts of urban limits, single use plastic wrappers and bags that were buried long ago, can be found in large quantities. Researchers have already identified the potentiality of microorganisms to biodegrade the plastic polymers. These microorganisms utilise plastic as a sole source of carbon and mineralise them into carbon dioxide under optimum environmental conditions. This paper provides a brief review on the biodegradation studies carried out by various researchers, spectra of microorganisms identified with the potential to degrade various polymeric substances, methods of testing and evaluations in order to quantify the effectiveness of degradation, their shortfalls and risks involved in implementing bioremediation technique in the field. A review on other related aspects that are deemed to be relevant to this topic are also discussed.

Biodegradation of Plastic Wastes in Soil: A Review on Testing and Evaluation Procedures

The recalcitrant behaviour of plastic creates an acute pollution on soil and aquatic biota. The plastic polymer synthesised from petroleum takes several hundred years to degrade. During excavation activities on the lands within or at the outskirts of urban limits, single use plastic wrappers and bags that were buried long ago, can be found in large quantities. Researchers have already identified the potentiality of microorganisms to biodegrade the plastic polymers. These microorganisms utilise plastic as a sole source of carbon and mineralise them into carbon dioxide under optimum environmental conditions. This paper provides a brief review on the biodegradation studies carried out by various researchers, spectra of microorganisms identified with the potential to degrade various polymeric substances, methods of testing and evaluations in order to quantify the effectiveness of degradation, their shortfalls and risks involved in implementing bioremediation technique in the field. A review on other related aspects that are deemed to be relevant to this topic are also discussed.

Inclusion of Pseudomonas fluorescens into soil-like fraction from municipal solid waste management park to enhance plastic biodegradation.

Single-use facial masks which are predominantly made out of polypropylene is being used and littered in large quantities during post COVID-19 situation. Extensive researches on bioremediation of plastic pollution on soil led to the identification of numerous plastic degrading microorganisms. These organisms assimilate plastic polymers as their carbon source for synthesizing energy. Pseudomonas fluorescens (PF) is one among such microorganism which is being identified to biodegrade plastic polymers in controlled environment. The natural biodegradation of facial mask in soil-like fraction collected from municipal waste management site, bioaugmentation of the degradation process with Pseudomonas fluorescens, biostimulation of the soil with carbonless nutritional supplements and combined bioaugmentation with biostimulation process were studied in the present work. The study has been conducted both in controlled and in natural condition for a period of 12months. The efficiency of the degradation was verified through FTIR analyses using carbonyl index, bond energy change, Loss in ignition (LOI) measurement along with CHNS analyses of residual substances. The analysis of results reported that carbonyl index (in terms of transmittance) was reduced to 46% of the control batch through the inclusion of PF in natural condition. The bioaugmented batch maintained in natural condition showed 33% reduction of LOI with respect to the control batch. The unburnt carbon content of the residual matter obtained from the furnace were analysed using CHNS analyser and indicated the lowest carbon content in the same bioaugmented batch. In this study, an attempt is made to verify the feasibility of enhancing biodegradation of single-use facial mask by bioaugmentation of soil-like fraction available in solid waste management park with Pseudomonas fluorescens under natural condition. CHNS and FTIR analysis assures the biodegradation of plastic waste in the soil-like fraction using Pseudomonas fluorescens under both controlled and natural environmental condition.

Advancements in the Bio-degradation of Plastic Waste into Value-added Chemicals: A Recent Perspective

Advancements in the Bio-degradation of Plastic Waste into Value-added Chemicals: A Recent Perspective

Biodegradation of low-density polyethylene by novel halophilic bacteria from mangrove ecosystem

Low-density polyethylene (LDPE) is identified as the primary constituent (approximately 18.9%) in plastic waste pollution. Crystalline structure, high molecular weight, and hydrophobic nature make LDPE recalcitrant to degradation. In the current study, the biodegradation of LDPE was studied by using three novel Malaysian mangrove bacterial isolates Brevundimonas naejangsanensis (strain MGS1), Arthrobacter crystallopoietes (strain SW4), and Arthrobacter pokkalii (strain PD2). Biodegradation of UV-treated LDPE was determined by the gradual increase in microbial count and production of laccase and lipase enzymes over a period of thirty days. All the isolates reduced the weight of the residual polymer and modified the chemical structure of LDPE by forming carbonyl and hydroxyl groups as a result of oxidation reactions by enzymes. Strain MGS1 reduced the maximum weight by 4.64 ± 0.5% and produced maximum laccase (2.19 ± 0.15 U/mL) and lipase enzyme (1.35 ± 0.05 U/mL). Field emission scanning electron microscopy (FESEM) showed visual images of bacterial colonization, and surface erosion (cracks/holes) on the LDPE surface. The production of enzymes reduced the hydrophobicity of the LDPE as evidenced by the biofilm formation, addition of new functional groups, surface erosion, and weight loss. The study is significant in addressing the biodegradation of plastic waste in Malaysia by exploring the mangrove microbiome.

Biodegradation of low-density polyethylene plastic waste by a constructed tri-culture yeast consortium from wood-feeding termite: Degradation mechanism and pathway

Polyethylene (PE) is one of the most common synthetic polymers, and PE waste pollution has been an environmental and health concern for decades. Biodegradation is the most eco-friendly and effective approach for plastic waste management. Recently, an emphasis has been placed on novel symbiotic yeasts isolated from termite guts as promising microbiomes for multiple biotechnological applications. This study might be the first to explore the potential of a constructed tri-culture yeast consortium, designated as DYC, isolated from termites for the degradation of low-density polyethylene (LDPE). The yeast consortium DYC stands for the molecularly identified species Sterigmatomyces halophilus, Meyerozyma guilliermondii, and Meyerozyma caribbica. The LDPE-DYC consortium showed a high growth rate on UV-sterilized LDPE as a sole carbon source, resulting in a reduction in tensile strength (TS) of 63.4% and a net LDPE mass reduction of 33.2% compared to the individual yeasts. All yeasts, individually and in consortium, showed a high production rate for LDPE-degrading enzymes. The hypothetical LDPE biodegradation pathway that was proposed revealed the formation of several metabolites, including alkanes, aldehydes, ethanol, and fatty acids. This study emphasizes a novel concept for using LDPE-degrading yeasts from wood-feeding termites for plastic waste biodegradation.

Potential of biological agents (Pseudomonas sp.) in plastic waste biodegradation process

<em>Pseudomonas sp.</em> can degrade plastics because it has an inducible operon system that produces certain enzymes (esterase, serine, hydrolase, and lipase) in the process of carbon source metabolism. The purpose of this study was to determine the potential of <em>Pseudomonas sp.</em> as a plastic biodegradation agent. This research method is a systematic literature review which is carried out by collecting, understanding, analyzing and concluding as many as 30 national and international journal articles published from 2008 to 2022 from several search engines such as Google Scholar, Ncbi, Sinta, and Plos one with the keywords degrading microorganisms plastic. The steps of this research were made samples to be used, tested samples with bacterial isolation, filtered the bacteria, bacterial bacteria and biodegradation within a specified time period by looking at the % loss of plastic before treatment. The results of the literature review analysis showed that <em>Pseudomonas sp.</em> able to degrade plastic around 2-19% by utilizing plastic as a carbon source which will convert addition and condensation polymers into simple molecules such as monomers, dimers and oligomers during the inventory period within 1-3 months. Thus, the microorganisms in the form of <em>Pseudomonas sp.</em> can decompose plastic waste naturally and faster than other methods and does not cause adverse effects.

Analysis of byproducts formed during biodegradation of plastic wastes by bacteria

Analysis of byproducts formed during biodegradation of plastic wastes by bacteria

Biodegradability of polyethylene mulch film by Bacillus paramycoides

Discarded polyethylene (PE) mulch film has led to persistent agricultural pollution. Biodegradation of plastic waste is considered as a promising solution that can potentially overcome environmental and economic problems. In this study, a novel bacterium (Bacillus paramycoides) was isolated from a waste mulch recycling plant and showed an extraordinary ability to customize polyethylene film. It was observed by scanning electron microscopy that a large number of pits and wrinkle cracks existed on the polyethylene, indicating that the strain used PE film as the sole carbon source. Meanwhile, the loss of weight of the film was tested continuously, and approximately 12% of the initial weight of the film was found to be lost within 45 days after coincubation with TW-2. The surface hydrophobicity of the polyethylene film decreased while the surface tension increased from 9.755 to 31.013. Fourier transform infrared (FTIR) analysis indicated that absorption peaks near 1740 cm−1 and 2760 cm−1 were attributed to the stretching vibrations of aldehyde and carboxyl groups, respectively, suggesting that hydrophilic groups were produced. This was also confirmed by XPS spectroscopy analysis. X-ray diffraction (XRD) analysis also showed that the relative crystallinity decreased from 33% to 11.51%. In addition, GPC analysis showed that the molecular weight decreased, while the proportion of low molecular weight fragments increased. These results strongly indicated that the PE film was able to be degraded to some extent by the strain. Finally, a new biodegradable mechanism for polyethylene was proposed.

A new continuous assay for quantitative assessment of enzymatic degradation of poly(ethylene terephthalate) (PET)

Enzymatic degradation of poly(ethylene terephthalate) (PET) has emerged as a promising route for ecofriendly biodegradation of plastic waste. Several discontinuous activity assays have been developed for assessing PET hydrolyzing enzymes, usually involving manual sampling at different time points during the course of the enzymatic reaction. In this work, we present a novel, compartmentalized UV absorbance assay for continuous detection of soluble hydrolysis products released during enzymatic degradation of PET. The methodology is based on removal of the walls separating two diagonally adjacent wells in UV-transparent microplates, to ensure passage of soluble enzymatic hydrolysis products between the two adjacent wells: One well holds an insoluble PET disk of defined dimensions and the other is used for continuous reading of the enzymatic product formation (at 240 nm). The assay was validated by quantifying the rate of mixing of the soluble PET degradation product BHET (bis(2-hydroxyethyl) terephthalate) between the two adjacent wells. The assay validation also involved a simple adjustment for water evaporation during prolonged assays. With this new assay, we determined the kinetic parameters for two PET hydrolases, DuraPETase and LCCICCG, and verified the underlying assumption of steady-state reaction rates. This new continuous assay enables fast exploration and robust kinetic characterization of PET degrading enzymes.

A Bibliometric Analysis of Research Trends in Biodegradation of Plastics.

The rapid growth in the production and application of plastic globally has resulted in plastic pollution with a negative impact on the environment, especially the marine ecosystem. One main disadvantage in the majority of polymers is disposal after a useful life span. Non-degradable polymers create severe difficulty in plastic waste management that might end up in landfills or wash into the ocean. The biodegradation of plastic waste is one solution to this critical problem of pollution. Hence, there is a need to consider the advancement of research in this subject area, in pursuit of a way out of plastic pollution. Thus, this study was designed to map the biodegradation of plastic-related research from 2000 to 2021. Statistical information on the topic was recovered from the Web of Science Core Collection and analysed using the bibliometrix package in RStudio statistical software, while data visualisation was conducted via VOSviewer. Our evaluation indicated that the amount of research on the biodegradation of plastic increased over the last decade, and the annual growth rate of publication trends was 11.84%. The study revealed that 1131 authors wrote the 290 analysed documents, with a collaboration index of 4.04. Cooper DG (n = 11) was the most relevant author, McGill University (n = 21) was the most active university, and the Journal of Polymers and the Environment (n = 19) the leading journal. The outcome of this study can guide prospective research and offer vital information for improving the management of plastic waste.

A Renew Microbial Degradation and Valorisation of Plastic Wastes Management in the Environment

Abstract: A developing accumulation of plastic wastes has turn out to be a severe environmental and social issue. It’s far urgent to expand innovative processes for the disposal of plastic wastes. In recent years, reports on biodegradation of synthetic plastics by using microorganisms or enzymes have sprung up, and those offer a opportunity to broaden biological treatment generation for plastic wastes. on this assessment, we've comprehensively summarized the microorganisms and enzymes which are able to degrade an expansion of normally used artificial plastics, which includes polyethylene (PE), polystyrene (PS), polypropylene (PP), polyvinyl chloride (%), polyurethane (PUR), and polyethylene terephthalate (pet). further, we have highlighted the microbial metabolic pathways for plastic depolymerization merchandise and the modern-day attempts in the direction of usage of such products as feedstock’s for microbial manufacturing of chemical substances with excessive fee. Taken together, these findings will contribute to building a theory of bio-up biking plastic wastes through connecting the biodegradation of plastic wastes to the biosynthesis of treasured chemical compounds in microorganisms. Closure, but not least, we've discussed the demanding situations in the direction of microbial degradation and valorization of plastic wastes. Plastics are found everywhere in the area and grow into a hot topic in educational circles. Big studies have focused on analytical techniques, source, abundance, transport, fate, degradation of plastics inside the environment and threats to herbal surroundings, wildlife or even human fitness. However, characteristics of plastic pollution, which might be important to recognize this rising problem, continue to be unknown to this point. Here, this paper opinion the essential characteristics of plastic pollutants within the environment to beautify present knowledge of this problem. Those traits, inclusive of diversity, persistence, global problems, mixed pollution and threats to organisms and human fitness, are severely summarized in this work. In addition, “plastic cycle” inside the environment, particularly, aquatic, atmospheric, and terrestrial device is also mentioned in this assessment. Sooner or later, we highlight current demanding situations of plastic pollution posed to the public and also suggest the studies developments in destiny paintings.

Polystyrene shaping effect on the enriched bacterial community from the plastic-eating Alphitobius diaperinus (Insecta: Coleoptera)

Plastic pollution has become a serious issue of global concern, and biodegradation of plastic wastes is representing one attractive environment-friendly alternative to traditional disposal paths. It is known that insects are involved in the plastic polymer degradation process, with reported evidence of tenebrionid beetle larvae capable to degrade polystyrene (PS), one of the most used plastics worldwide. Recently, a ribosomal RNA based survey on the insect gut microbiota of the lesser mealworm Alphitobius diaperinus has revealed differentially abundant microbial taxa between PS-fed larvae and control group. Following these findings, an enrichment bacterial culture was set up in liquid carbon-free basal medium with PS film as sole carbon source using PS-fed larvae of A. diaperinus as inoculum. After two-months the culture was analysed both by molecular and culture-based methods. Isolated bacteria which had become prevalent under the selective enrichment conditions resulted ascribable to three taxonomic groups: Klebsiella, Pseudomonas, and Stenothrophomonas. The predominance of these groups in PS-fed larvae was confirmed by using bacterial 16S rRNA gene amplicon sequencing, and it was consistent with the results of previous reports. Isolated bacteria were able to attach to PS surfaces and SEM observations showed the presence of thin fibrillar structures connecting the bacterial cells to the abiotic surface.

Isolation and Characterization of Polyvinyl Chloride (PVC) Degrading Bacteria from Polluted Sites of Gwalior City, M.P., India

Plastic is harmful to nature and this issue could be solved by its degradation. Biodegradation of plastic waste utilizing bacterial strain is an eco-friendly approach. In this study, top bacterial strains that degrade the polymeric ingredient of the polymer polyvinyl chloride (PVC) were isolated and identified using a development culture procedure. For this investigation, soil from various contaminated areas was collected, which had abundant plastic waste. The biodegradation of polyvinylchloride films was studied using a liquid culture approach for six months. A couple of bacterial organism packs were then limited to emulsifying the commonly used PVC polymer in agar media. The PVC strain showed particular degradation and was chosen for further testing because the species Bacillus and Micrococcus were considered more credible. Bacillus and Micrococcus species have both proven the biodegradability of PVC based on the mean weight decrease, which was 0.873 for Bacillus species and 0.916 for Micrococcus species after a period of around six months. The FTIR study confirmed the breaking down by demonstrating the proximity of porosity and sensitivity of bacteria-infested polythene surfaces. Bacillus has a higher degradation potential than Micrococcus in our research.

Membrane composition and successful bioaugmentation. Studies of the interactions of model thylakoid and plasma cyanobacterial and bacterial membranes with fungal membrane-lytic enzyme Lecitase ultra

Cyanobacterial/bacterial consortia are frequently inoculated to soils to increase the soil fertility and to accelerate the biodegradation of organic pollutants. Moreover, such consortia can also be successfully applied in landfills especially for the biodegradation of plastic wastes. However, the bioaugmentation techniques turn out frequently inefficient due to the competition of the indigenous microorganisms attacking directly these inoculated or secreting to their surroundings cell wall and membrane-lytic enzymes. It can be hypothesized that the resistance of the microbial membrane to the enzymatic degradation is correlated with its lipid composition. To verify this hypothesis glycolipid and phospholipid Langmuir monolayers were applied as models of thylakoid and plasma cyanobacterial and bacterial membranes. Hybrid fungal enzyme Lecitase ultra joining the activity of lipase and phospholipase A1 was applied as the model of fungal membrane-lytic enzyme. It turned out that anionic thylakoid lipids sulfoquinovosyldiacylglycerol and phosphatidylglycerols were the main targets of Lecitase ultra in the model multicomponent thylakoid membranes. The resistance of the model plasma bacterial membranes to enzymatic degradation depended significantly to their composition. The resistance increased generally when the unsaturated lipids were exchanged to their saturated counterparts. However, most resistant turned out the membranes composed of unsaturated phosphatidylamine and saturated anionic phospholipids.

Plastic Waste Biodegradation by Local Bacterial Isolates in Ramadi City

The current study aims to study biodegradation for plastic waste as one of the ways of treatment of plastic pollution by using isolated bacterial isolates from plastic waste collection and landfill areas in the city of Ramadi and surrounding areas during different periods. Diagnosis of bacterial isolates was performed based on phenotypic and physiological tests as well as testing on the VITEK 2 system, isolates were selected that go back to the type Pseudomonas sp. and Streptomyces sp. Bacterial isolates have been studied for its ability to breakdown plastic waste used in the manufacturing of drinking bottles and shopping bags by collecting samples of plastic waste and assured they are washed and sterilized perfectly. Another experiment was conducted through a second decomposition (A carbon deficient) medium as well as the second decomposition medium contains some chemicals that are thought to help accelerate the process of decomposition. Results showed that the highest polyethylene breakdown occurred due to isolate P1 (Pseudomonas fluorescens) by the degradation rate 8.83% on the first decomposition medium and 30.5% on the second decomposition medium, while the degradation rate to isolated P4 (Streptomyces) was 4.83% on the first medium and 19% on the second medium. The genetic study results showed existence of the enzyme PETase gene on Pseudomonas fluorescens chromosome in an expected size 119bp and it was absent on plasmid.

Emerging Roles of PETase and MHETase in the Biodegradation of Plastic Wastes.

Polyethylene terephthalate (PET) is extensively used in plastic products, and its accumulation in the environment has become a global concern. Being a non-degradable pollutant, a tremendous quantity of PET-bearing plastic materials have already accumulated in the environment, posing severe challenges towards the existence of various endangered species and consequently threatening the ecosystem and biodiversity. While conventional recycling and remediation methodologies so far have been ineffective in formulating a "green" degradation protocol, the bioremediation strategies-though nascent-are exhibiting greater promises towards achieving the target. Very recently, a novel bacterial strain called Ideonella sakaiensis 201-F6 has been discovered that produces a couple of unique enzymes, polyethylene terephthalate hydrolase and mono(2-hydroxyethyl) terephthalic acid hydrolase, enabling the bacteria to utilize PET as their sole carbon source. With a detailed understanding of the protein structure of these enzymes, possibilities for their optimization as PET degrading agents have started to emerge. In both proteins, several amino acids have been identified that are not only instrumental for catalysis but also provide avenues for the applications of genetic engineering strategies to improve the catalytic efficiencies of the enzymes. In this review, we focused on such unique structural features of these two enzymes and discussed their potential as molecular tools that can essentially become instrumental towards the development of sustainable bioremediation strategies. Degradation PET by wild type and genetically engineered PETase and MHETase. Effect of the MHETase-PETase chimeric protein and PETase expressed on the surface of yeast cells on PET degradation is also shown.

Landfill microbiome harbour plastic degrading genes: A metagenomic study of solid waste dumping site of Gujarat, India.

Globally, environmental pollution by plastic waste has become a severe ecological and social problem worldwide. The present study aimed to analyse the bacterial community structure and functional potential of the landfill site using high throughput shotgun metagenomic approach to understand plastic degrading capabilities present in the municipal solid waste (MSW) dumping site. In this study, soil, leachate and compost samples were collected from various locations (height and depth) of the Pirana landfill site in Ahmedabad city Gujarat, India. In total 30 phyla, 58 class, 125 order, 278 families, 793 genera, and 2468 species were predicted. The most dominant phyla detected were Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria in the soil and compost samples. Whereas, in leachate samples, the predominant phyla belonged to Firmicutes (54.24%) followed by Actinobacteria (43.67%) and Proteobacteria (1.02%). The functional profiling revealed the presence of enzymatic groups and pathways involved in biodegradation of xenobiotics. The results also demonstrated the presence of potential genes that is associated with the biodegradation of different types of plastics such as polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS). Present study extablishes the relationship between microbial community structure and rich sources of gene pool, which are actively involved in biodegradation of plastic waste in landfill sites.

Greater Biofilm Formation and Increased Biodegradation of Polyethylene Film by a Microbial Consortium of Arthrobacter sp. and Streptomyces sp.

The widespread use of polyethylene (PE) mulch films has led to a significant accumulation of plastic waste in agricultural soils. The biodegradation of plastic waste by microorganisms promises to provide a cost-effective and environmentally-friendly alternative for mitigating soil plastic pollution. A large number of microorganisms capable of degrading PE have been reported, but degradation may be further enhanced by the cooperative activity of multiple microbial species. Here, two novel strains of Arthrobacter sp. and Streptomyces sp. were isolated from agricultural soils and shown to grow with PE film as a sole carbon source. Arthrobacter sp. mainly grew in the suspension phase of the culture, and Streptomyces sp. formed substantial biofilms on the surface of the PE film, indicating that these strains were of different metabolic types and occupied different microenvironments with contrasting nutritional access. Individual strains were able to degrade the PE film to some extent in a 90-day inoculation experiment, as indicated by decreased hydrophobicity, increased carbonyl index and CO2 evolution, and the formation of biofilms on the film surface. However, a consortium of both strains had a much greater effect on these degradation properties. Together, these results provide new insights into the mechanisms of PE biodegradation by a microbial consortium composed of different types of microbes with possible metabolic complementarities.