Biodegradation Of Polyethylene Research Articles

Effect of cold plasma pretreatment on biodegradation of high-density polyethylene (HDPE) and polystyrene (PS)

AbstractCold atmospheric plasma (CAP) pretreatment of high-density polyethylene (HDPE) and polystyrene (PS) was investigated to evaluate its effect on biodegradation. Weight and wettability measurement, surface topography, and roughness analysis were examined for physical properties evaluation. Fourier-transform infrared spectroscopy (FT-TR) analysis was conducted to understand the possible chemical transformation. Based on biofilm formation, the highest microbial colonisation was observed on the sample treated with CAP pretreatment + biotreatment, which was 0.56 and 0.19 (at OD 595 nm) for HDPE and PS, respectively. A biodeterioration effect characterised by weight loss and changes of hydrophobicity in which hydrophobicity reductions of 5.1 ± 0.64% and 12° ± 0.35° were observed with the pretreated HDPE within 50 days, respectively. No physical weight loss was detected in the PS sample, but significant surface corrosion was observed. Atomic force microscopy (AFM) also showed a higher surface degradation of 10 and 35% for CAP pretreated HDPE and PS incubated with microorganisms compared to virgin samples incubated in the same condition. Moreover, chemical transformation indicated a new peak (C–O) in CAP-pretreated PE samples before and after 50 days of biodegradation. The experiments with virgin HDPE and PS demonstrated a positive effect of the pretreatment on the biodegradation process.

Isolation and characterization of new bacterial 1 strains degrading low-density polyethylene

Plastics have become indispensable in everyday life due to their properties. For this reason, the accumulation of polymer waste in the natural environment is becoming a serious global problem. The aim of the research was to isolate microorganisms capable of biodegrading plastics. The studies focused on the biodegradation of low-density polyethylene as the most common polymer. Seven and five bacterial strains were isolated from the landfill and compost, respectively. The morphological and biochemical characteristics of the isolates were determined. These isolates were able to survive in an environment where the only carbon source was LDPE, but no increase in biomass was obtained. However, analysis of the spectra obtained by the ATR-FTIR method showed the formation of chemical changes on the polymer surface. Bacterial biofilm formation was visualized by scanning electron microscopy. The toxicity of plastic biodegradation products in a liquid environment was tested and their safety for plants was confirmed. However, these biodegradation products have acute lethal toxicity for the Daphnia magna. LDPE films were pre-treated with H 2O 2, HNO 3, or heat. The biodegradation of HNO 3-treated LDPE by isolated bacteria was the most significant. The weight loss was approximately 8%, and 6%, for landfill and compost-isolated bacterial strains, respectively.

Biodegradation of polyethylene in digestive gland homogenates of marine invertebrates.

Вiotic factors may be the driving force of plastic fragmentation along with abiotic factors. Since understanding the processes of biodegradation and biological depolymerization of plastic is important, a new methodological approach was proposed in this study to investigate the role of marine invertebrate digestive enzymes in plastic biodegradation. The aim of this study is to evaluate the possibility of enzymatic biodegradation of polyethylene fragments in the digestive gland homogenate of marine invertebrates differing in their feeding type (Strongylocentrotus nudus, Patiria pectinifera, Mizuhopecten yessoensis). Significant changes are found in the functional groups of the polymer after 3 days of incubation in the digestive gland homogenates of the studied marine invertebrates. A significant increase in the calculated CI (carbonyl index) and COI (сarbon-oxygen index) indices compared to the control sample was observed. The results suggest that digestive enzymes of studied organisms may play an important role in the biogeochemical cycling of plastic.

Biodegradation of polyethylene and polystyrene by Zophobas atratus larvae from Bangladeshi source and isolation of two plastic-degrading gut bacteria

Plastic pollution has become a major environmental concern globally, and novel and eco-friendly approaches like bioremediation are essential to mitigate the impact. Low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and expanded polystyrene (EPS) are three of the most frequently used plastic types. This study examined biodegradation of these using Zophobas atratus larvae, followed by isolation and whole genome sequencing of gut bacteria collected from larvae frass. Over 36 days, 24.04 % LDPE, 20.01 % EPS, and 15.12 % LLDPE were consumed on average by the larvae, with survival rates of 85 %, 90 %, and 87 %, respectively. Fourier transform infrared spectroscopy (FTIR) analysis of fresh plastic types, consumed plastics, and larvae frass showed proof of plastic oxidation in the gut. Frass bacteria were isolated and cultured in minimal salt media supplemented with plastics as the sole carbon source. Two isolates of bacteria were sampled from these cultures, designated PDB-1 and PDB-2. PDB-1 could survive on LDPE and LLDPE as carbon sources, whereas PDB-2 could survive on EPS. Scanning Electron Microscopy (SEM) provided proof of degradation in both cases. Both isolates were identified as strains of Pseudomonas aeruginosa, followed by sequencing, assembly, and annotation of their genomes. LDPE- and LLDPE-degrading enzymes e.g., P450 monooxygenase, alkane monooxygenase, alcohol dehydrogenase, etc. were identified in PDB-1. Similarly, phenylacetaldehyde dehydrogenase and other enzymes involved in EPS degradation were identified in PDB-2. Genes of both isolates were compared with genomes of known plastic-degrading P. aeruginosa strains. Virulence factors, antibiotic-resistance genes, and rhamnolipid biosurfactant biosynthesis genes were also identified in both isolates. This study indicated Zophobas atratus larvae as potential LDPE, LLDPE, and EPS biodegradation agent. Additionally, the isolated strains of Pseudomonas aeruginosa provide a more direct and eco-friendly solution for plastic degradation. Confirmation and modification of the plastic-degrading pathways in the bacteria may create scope for metabolic engineering in the future.

Polyethylene Biodegradation by an Artificial Bacterial Consortium: Rhodococcus as a Competitive Plastisphere Species.

Polyethylene (PE), a widely used recalcitrant synthetic polymer, is a major global pollutant. PE has very low biodegradability due to its rigid C-C backbone and high hydrophobicity. Although microorganisms have been suggested to possess PE-degrading enzymes, our understanding of the PE biodegradation process and its overall applicability is still lacking. In the present study, we used an artificial bacterial consortium for PE biodegradation to compensate for the enzyme availability and metabolic capabilities of individual bacterial strains. Consortium members were selected based on available literature and preliminary screening for PE-degrading enzymes, including laccases, lipases, esterases, and alkane hydroxylases. PE pellets were incubated with the consortium for 200 days. A next-generation sequencing ana-lysis of the consortium community of the culture broth and on the PE pellet identified Rhodococcus as the dominant bacteria. Among the Rhodococcus strains in the consortium, Rhodococcus erythropolis was predominant. Scanning electron microscopy (SEM) revealed multilayered biofilms with bacteria embedded on the PE surface. SEM micrographs of PE pellets after biofilm removal showed bacterial pitting and surface deterioration. Multicellular biofilm structures and surface biodeterioration were observed in an incubation of PE pellets with R. erythropolis alone. The present study demonstrated that PE may be biodegraded by an artificially constructed bacterial consortium, in which R. erythropolis has emerged as an important player. The results showing the robust colonization of hydrophobic PE by R. erythropolis and that it naturally possesses and extracellularly expresses several target enzymes suggest its potential as a host for further improved PE biodeterioration by genetic engineering technology using a well-studied host-vector system.

SCREENING OF LACCASE AND MANGANESE PEROXIDASE ACTIVITIES PRODUCED BY ESCHERICHIA COLI AND PENICILLIUM ITALICUM ISOLATED FROM PLASTIC WASTE SITE IN AKURE, NIGERIA

Objective: To determine the microbial growth of Echerichia coli and Penicillium Italicum on polyethylene (PE) and screen for the activities of Manganese Peroxidase (MnP) and Laccase produced by the two microbial strain (Echerichia coli and Penicillium Italicum). Methods: Polyethylene (PE) used were obtained from Elizade university dumpsite Ilara-mokin, Ondo State. The polyethylene (PE) were cut into tiny pieces, rinsed with distilled water and then used as the sole carbon source for the growth of microorganisms in an orbital shaker flask. Laccase and manganese (Mnp) peroxidase activity were assayed in Escherichia coli and Penicillium italicum spectrophometrically as they utilize polyethylene (PE) as a carbon source. Results: Escherichia coli growth was at 0.002 at 0 h, rose to the exponential phase at 96 h, and declined to the death phase at 144 h. Penicillium italicum growth was at 0.004 at 0 h, rose to the exponential phase at 72 h, and declined to the death phase at 144 h. Laccase activity was 9.2 (U/ml) in Echerichia coli and manganese peroxidase (MnP)was 5.25 (U/ml) in Echerichia coli. Manganese peroxidase (MnP) was 10.643(U/ml) in Penicillium italicum while laccase activity was 9.5(U/ml) in Penicillium italicum. Conclusion: Echerichia coli and penicillium italicum showed Manganese peroxidase and Lacasse activities as they utilized polyethylene (PE) as carbon source. Hence, they should be explored for biodegradation of polyethylene (PE).

Biodegradation of Low-Density Polyethylene (LDPE) by Aspergillus niger

The current study focused on the ability of Aspergillus niger to biodegrade low-density polyethylene, while studying some of the factors affecting the biodegradation process, including pH and temperature. Samples were collected from the soil of the waste landfill (sanitary landfill) of Dhi Qar Governorate, located 20 kilometers south of the center of the governorate, and using the dilution method. The genus Aspergillus niger had the highest appearance rate, reaching 100%, as it appeared in all samples, and the colony diameters in the solid medium were calculated. The fungus showed the ability to adapt and grow in the medium containing low-density polyethylene, with the a concentration of (0.1, 0.5, 1)%, and temperature of (15, 25, 35) ᵒC, also pH (2, 4, 6), and the addition of a carbon source of glucose, maltose and a nitrogen source (NH4Cl, NaNo3), the decomposition metabolites and the remaining concentration were identified by using Fourier – transform Infrared Spectroscopy and Gas – Mass Spectroscopy, and later a confirmatory test was conducted to determine the ability of Aspergillus niger to biodegrade low-density polyethylene in the medium of mineral salts.

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.

Application of laccase produced by marine actinomycetes in accelerating the rate of biodegradation of polyethylene

Although plastic is very useful in modern life, its widespread use could impair human sustainability. Improper plastic waste management generates greenhouse gases and harmful waste. Plastics and its associated by-products, such as microplastics, accumulate on land and in the oceans causing harm to human and ecological health. An environmentally friendly solution, such as enzymes-mediated biocatalytic depolymerization, is required for efficient management of the large amount of waste generated around the world. Actinomycetes are less explored for commercial biodegradation processes but have attracted attention since they constitute a significant proportion of the soil and aquatic flora and because of their ability to degrade complex materials. This study involves identification of laccase-producing marine actinomycetes and examining the possibility of accelerating the rate of biodegradation of polyethylene by treating with laccase enzyme. The polyethylene test material treated with laccase enzyme for 30 days shows 9.36 percent rate of biodegradation, which was six times higher than the rate of biodegradation of an untreated one. The change in the chemical structure of the polyethylene was studied using Fourier transform infrared spectroscopy. After treatment with laccase enzyme, the carbonyl index of the polyethylene test material increased to 1.25 indicating that the polymer was oxidized, and post biodegradation study showed that the carbonyl index decreased to 0.66 which confirms the concept that oxidized polymer was utilized by the microorganisms. The laccase-producing isolate A-09 showed 99 percent identity as Streptomyces rubiginosus based on molecular fingerprinting.

Investigation on the effect of several parameters involved in the biodegradation of polyethylene (PE) and low-density polyethylene (LDPE) under various seawater environments

This work investigates the biodegradation of polyethylene (PE) and low-density polyethylene (LDPE) and the leaching of their harmful additives. Micro/macro-plastics of both types were subjected to different laboratory-controlled conditions for 3 months. Gas Chromatography-Mass Spectroscopy (GC–MS) results revealed that leachate concentrations ranged from 0.40 ± 0.07 μg/L to 96.36 ± 0.11 μg/L. It was concluded that the additives' leaching process was promoted by light. However, light was not the only factor examined; microorganisms, pH, salinity, aeration/mixing and temperature influenced the biodegradation process, too. GC–MS results showed a prodigious impact on the biodegradation process when Pseudomonas aeruginosa was added to the artificial seawater compared to plastics exposed to light/air only. Scanning Electron Microscopy (SEM) micrographs demonstrated a significant alteration in the plastics' morphologies. Similarly, Fourier-Transform Infrared Spectroscopy (FTIR) spectra showed obvious changes in plastics characteristic peaks, especially microplastics. Furthermore, it was shown that PE was more susceptible to degradation/biodegradation than LDPE. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) findings showed that some toxic metals were present in water samples after experiments, with concentrations above the permissible limits. For instance, bio-augmentation/bio-stimulation experiments showed that the concentrations of Pb, Sr, and Zn were 0.59 mg/L, 70.09 mg/L, and 0.17 mg/L, respectively; values above the permissible limits. It is crucial to emphasise that plastics must be meticulously engineered to avoid environmental and human impacts, originated from their degradation by-products. Furthermore, a holistic approach engaging stakeholders, researchers, policymakers, industries and consumers, is essential to effectively tackle the global challenge of marine plastic pollution.

Biodegradation of low-density polyethylene by plasma-activated Bacillus strain

Plastic biodegradation by microorganisms is an eco-friendly and sustainable method without any ramifications. Herein, we used a cultivation method and 16S rRNA sequencing to screen bacteria that can efficiently colonize and degrade low-density polyethylene (LDPE) from various plastic wastes. We identified Bacillus safensis BS-10L through whole-genome sequencing analysis and verified its LDPE-degradation ability. However, the decomposition mechanism of the isolated bacteria was unclear and the decomposition efficiency was insufficient, so low-temperature plasma was used to increase the decomposition efficiency of the bacteria. The population and viability of bacteria treated with cold plasma increased. Plasma-activated bacteria could induce cracks, holes, and roughness on the surface of LDPE films over 90 days, and over 30 days; the LDPE film lost 13.40 ± 0.013% and 27.78 ± 0.014% of its mass by BS-10L and plasma-treated BS-10L, respectively. Fourier-transform infrared spectroscopic analysis identified new peaks of the C=O and C-O groups in the plasma-treated LDPE film, exhibiting high transmittance in the LDPE film that was inoculated with bacteria. X-ray photoelectron spectroscopic analysis showed that C-O bonds were generated by BS-10L strain, and relatively strong C=O bonds were generated in the film inoculated with plasma-treated BS-10L strain. Plasma treatment increased the colonization of the BS-10L strain and changed the chemical bonding of the LDPE film, suggesting that plasma-activated BS-10L could accelerate decomposition by oxidation by increasing the carbonyl group of the PE film. Therefore, plasma technology may be effective for enhancing the plastic-degrading ability of microorganisms.

Investigating biodegradation of polyethylene and polypropylene microplastics in Tehran DWTPs.

Microplastic (MP) pollution is a growing concern and various methods are being sought to alleviate the level of pollution worldwide. This study investigates the biodegradation capacity of MPs by indigenous microorganisms of raw water from Tehran drinking water treatment plants. By exposing polypropylene (PP) and polyethylene (PE) MPs to selected microbial colonies, structural, morphological, and chemical changes were detected by scanning electron microscope (SEM), cell weight measurement, Fourier transform infrared (FTIR), Raman spectroscopy test, and thermal gravimetric analysis (TGA). Selected bacterial strains include Pseudomonas protegens strain (A), Bacillus cereus strain (B), and Pseudomonas protegens strain (C). SEM analysis showed roughness and cracks on PP MPs exposed to strains A and C. However, PE MPs exposed to strain B faced limited degradation. In samples related to strain A, the Raman spectrum was completely changed, and a new chemical structure was created. Both TGA and FTIR analysis confirmed changes detected by Raman analysis of PP and PE MPs in chemical changes in this study. The results of cell dry weight loss for microbial strains A, B, and C were 13.5, 38.6, and 25.6%, respectively. Moreover, MPs weight loss was recorded at 32.6% for PP MPs with strain A, 13.3% for PE MPs with strain B, and 25.6% for PP MPs with strain C.

Improved biodegradability of low-density polyethylene using plasma pretreatment and plastic-degrading bacteria

Polyethylene is widely used and is a major cause of serious environmental problems because it is non-biodegradable and difficult to recycle. To overcome these environmental problems, in this study, low-density polyethylene (LDPE) was treated with low-temperature plasma at atmospheric pressure, an eco-friendly technology. After inducing oxidation on the LDPE film by plasma treatment, a method for improving the biodegradation efficiency of LDPE-degrading bacteria was identified, and the underlying mechanism was investigated. Fourier-transform infrared and X-ray photoelectron spectroscopy analyses showed that the plasma treatment resulted in the formation of new peaks corresponding to the C–O and –CC– bonds and stronger –CO– bond groups than the –C–O– bond groups, showing that the oxidation of LDPE film was strong. Additionally, the –C–H– bond ratio on LDPE surfaces inoculated with Pseudomonas putida increased by 13–25.5% compared to that on untreated controls. Pseudomonas putida reduced the thermal stability by forming a biofilm on the oxidized LDPE film during the plasma treatment. The weight of untreated LDPE film was reduced by 50%, while that of treated LDPE film was reduced by 80%, confirming more efficient degradation. Thus, LDPE decomposition efficiency can be improved using a short plasma treatment to increase the adhesion and fixation of LDPE-degrading bacteria on the surface of oxidized LDPE films. Therefore, plasma pretreatment technology could be used to reduce plastic contamination in agricultural environments.

Significance of landfill microbial communities in biodegradation of polyethylene and nylon 6,6 microplastics

Plastic pollution, particularly microplastics, poses a significant environmental challenge. This study aimed to address the urgent need for sustainable solutions to manage plastic waste. The degradation of polyethylene microplastics (PEMPs) and nylon 6,6 microplastics (NMPs) were investigated using bacterial culture isolates, isolated from a municipal landfill site and identified through 16 S rDNA as well as metagenomics techniques.The study demonstrated for the first time along with degradation mechanism. The isolates identified as Achromobacter xylosoxidans and mixed culture species in dominance of Pulmonis sp. were used to degrade PEMPs and NMPs. Achromobacter xylosoxidans reduced microplastic’s dry weight by 26.7% (PEMPs) and 21.3% (NMPs) in 40 days, while the mixed culture achieved weight reductions of 19.3% (PEMPs) and 20% (NMPs). The release of enzymes, laccase and peroxidases revealed C-C bond cleavage and reduced polymer chain length. The thermal studies (TGA and DSC) revealed changes in the thermal stability and transition characteristics of microplastics. The structural alterations on PEMPs and NMPs were recorded by FTIR analysis. Byproducts such as alkanes, esters, aromatic compounds and carboxylic acids released were identified by GC-MS. These results suggest the effectiveness of bacterial isolates in degrading PEMPs and NMPs, with potential for sustainable plastic waste management solutions.

Biofilm formation promoted biodegradation of polyethylene in Gordonia polyisoprenivorans B251 isolated from bacterial enrichment acclimated by hexadecane for two years

Polyethylene (PE) mulch films have been widely used in agriculture and led to a significant pollution in cultivated soils. It is desirable to develop the sustainable method for the degradation of PE. As an environment friendly approach, microbial or enzymatic degradation of PE could meet this demanding. Thus, more microbial strains are required for illustrating biodegrading pathway and developing efficient biological method. In this study, Gordonia polyisoprenivorans B251 capable of degrading PE was isolated from bacterial enrichment with hexadecane as a sole carbon source for two years, in which genus Gordonia had dominated. As revealed by microbial growth curve, the strain B251 had the highest growth rate than other tested strains in the mediums either with hexadecane or PE particles as sole carbon source. The formation of biofilms in both enriched culture and G. polyisoprenivorans B251 pure culture attached to PE film was observed. The capability for PE degradation of individual strain was screened by 30-day incubation with PE film and confirmed by the presence of hydroxyl, carbonyl, carbon-carbon double bond and ether groups in FT-IR analysis and cracks on the surface of PE film observed by scanning electron microscopy (SEM). Therefore, Gordonia polyisoprenivorans, reported as their degradation of environmental contaminants in previous study, were also identified in current study as a candidate for polyethylene biodegradation.

Unveiling Fragmentation of Plastic Particles during Biodegradation of Polystyrene and Polyethylene Foams in Mealworms: Highly Sensitive Detection and Digestive Modeling Prediction.

It remains unknown whether plastic-biodegrading macroinvertebrates generate microplastics (MPs) and nanoplastics (NPs) during the biodegradation of plastics. In this study, we utilized highly sensitive particle analyzers and pyrolyzer-gas chromatography mass spectrometry (Py-GCMS) to investigate the possibility of generating MPs and NPs in frass during the biodegradation of polystyrene (PS) and low-density polyethylene (LDPE) foams by mealworms (Tenebrio molitor larvae). We also developed a digestive biofragmentation model to predict and unveil the fragmentation process of ingested plastics. The mealworms removed 77.3% of ingested PS and 71.1% of ingested PE over a 6-week test period. Biodegradation of both polymers was verified by the increase in the δ13C signature of residual plastics, changes in molecular weights, and the formation of new oxidative functional groups. MPs accumulated in the frass due to biofragmentation, with residual PS and PE exhibiting the maximum percentage by number at 2.75 and 7.27 μm, respectively. Nevertheless, NPs were not detected using a laser light scattering sizer with a detection limit of 10 nm and Py-GCMS analysis. The digestive biofragmentation model predicted that the ingested PS and PE were progressively size-reduced and rapidly biodegraded, indicating the shorter half-life the smaller plastic particles have. This study allayed concerns regarding the accumulation of NPs by plastic-degrading mealworms and provided critical insights into the factors controlling MP and NP generation during macroinvertebrate-mediated plastic biodegradation.

Biodegradation of polyethylene, biodegradable-polyethylene bags and corn residues using Tenebrio molitor larvae

The degradation capacity of different types of plastic from its ingestion by mealworms (the larvae of Tenebrio molitor), as well as its survival, was studied. Bags build from plastic nominally known as low-density polyethylene (LDPE); compostableplastic, made from corn waste (CPE); and polyethylene with d2w technology (d2wPE) plastic, were used. T. molitor larvae were subjected to a 7-day starvation period and then only fed with the different types of plastics for 56 days. Two groups of samples were prepared with the different plastics. On the one hand, the plastics were exposed to a UV photodegradation pretreatment from 260 to 285 nm and then used as the only source of food for the larvae. On the other hand, the same experiment was carried out without the UV pretreatment. The objective was to compare the possible effects of UV radiation on the plastics and their subsequent degradation by the larvae. The maximum degradation rates with UV pretreatment were 98%, 77% and 4% for CPE, LDPE, and d2wPE samples, respectively. Degradation rates without pretreatment were 79%, 54%, and 3%, and were obtained in the same order. In both scenarios, larval survival was significantly affected just for the d2wPE samples, reaching an average mortality rate of 98%. For the rest of the samples, the average mortality rate was only 12%.

Comparison study on low-density polyethylene film biodegradation potential of Achoria grisella and Galleria mellonella larvae

Aim: The current research investigates biodegradation of Low-Density Polyethylene (LDPE) facilitated with and without gut microbiota in Galleria mellonella and Achoria grisella. Methodology: A batch of 50 larvae of Galleria mellonella and Achoria grisella administered with antibiotics (A group) along with larvae not fed with antibiotics (WA group) were exposed to LDPE film. After biodegradation, the weight loss of degraded LDPE film, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis, and Gas Chromatography-Mass Spectroscopy analysis were performed to confirm the plastic biodegradation potential of selected insects. Results: In a and WA groups, the post-biodegradation for a selected species of wax moth exhibited weight loss of 2.763%, 0.789%, 5.403% and 1.481%, respectively. The SEM images revealed that both A and WA groups were capable of LDPE film disintegration. The FTIR of biodegraded film confirmed the deterioration of LDPE by indicating a change in the typical peaks of C−H and H−C−H bonds that points out the biodegradation of polyethylene.Further, the thermogravimetric analysis showed a substantial mass loss in the LDPE flakes consumed by the insects, demonstrating a decline in the thermal stabilities of disintegrated polymers. GC-MS of frass validated the presence of many component groups, including alkanes, alcohols, esters, ethers and acids, which confirmed the biodegradation of LDPE. Interpretation: Wax worms possess the capacity to biodegrade LDPE, independent of gut microbiota Key words: Achoria grisella, Antibiotic, Galleria mellonella, Low-density polyethylene

Environmental Toxicity, Human Hazards and Bacterial Degradation of Polyethylene

Plastics are the most rapidly growing materials in terms of production and consumption. The durability, inertness, light weight, flexibility, and low cost are the key characteristics that make plastic suitable for application in various fields, including the construction, automotive, electronics, and packaging industries. Due to widespread usage in daily life and many industrial processes and operations, more than 300 million tons of plastic waste are produced globally annually. Indiscriminate use of plastics such as polyethylene causes environmental pollution and impacts human health due to irreversible changes in the ecological cycle. Due to its low biodegradability, polyethylene accumulation has recently emerged as a momentous environmental concern. The conventional methods, such as recycling or disposing of polyethylene, are exorbitant, and incineration results in the emission of toxic chemical compounds. Therefore, the most recent research progressively focused on the biodegradation of polyethylene with the application of bacteria as novel approaches to counteract plastic waste. This review summarizes the type of polyethylene and the environmental issues. It also briefly discussed the genes and enzymes of bacteria involved in the degradation of polyethylene. In addition, it attempts to address factors influencing degradation and techniques used for monitoring degradation.

Biodegradation of low-density polyethylene (IDPE) by bacteria isolated from dump sites in some metropolitan cities in north central Nigeria

In this study, biodegradation of Low-Density Polyethylene (LDPE) by bacteria isolated from dump sites was evaluated in a liquid Basal Salts Medium. The bacteria, including Psuedomonas aeruginosa, Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis, Enterobacter hormaechei, Klebsiella pneumonia and Proteus vulgaris were isolated from soil samples taken from municipal dump sites in some metropolitan cities in North Central Nigeria, namely, Abuja, Makurdi and Jos and screened for their ability to utilize LDPE using the clear zone method. 0.500 gram waste LPDE strips (1 cm x 5 cm) were placed into a 500 milliliter flask containing sterilized liquid medium at 30 °C and incubated in a rotary shaker for eight (8) weeks. Each bacterium was added to a separate flask. Biodegradation was measured by pH changes of the media and gravimetrically by weight loss of the waste LDPE strips two weekly during the incubation period. The results obtained showed a gradual decrease in the pH of the media originally set at 7.05 with incubation time for all isolated bacteria. Psuedomonas aeruginosa and Providencia stuarti recorded the highest weight loss of the LDPE strips after eight (8) weeks at 19.80±0.04 %, with a final pH of 3.75±0.01 and 19.20±0.42 %, and final pH 4.85±0.01 respectively followed by Bacillus megaterium at 13.40±0.10% and final pH of 3.95±0.01. Klebsiella pnuemonia and Proteus vulgaris recorded the least gravimetric weight loss at 1.40±0.02 %, with a final pH of 4.75±0.01 and 0.80±0.01 %, pH 4.85±0.01 respectively. This work reveals that bacteria play a vital role in the degradation of low-density polyethylene waste in the natural environment. This can be applied to the development of commercial bioreactors in the future for the degradation of polyethylene wastes.