Low-density Polyethylene Degradation Research Articles

Bacterial Degradation of Low-Density Polyethylene Preferentially Targets the Amorphous Regions of the Polymer.

Low-density polyethylene (LDPE) is among the most abundant synthetic plastics in the world, contributing significantly to the plastic waste accumulation problem. A variety of microorganisms, such as Cupriavidus necator H16, Pseudomonas putida LS46, and Pseudomonas chlororaphis PA2361, can form biofilms on the surface of LDPE polymers and cause damage to the exterior structure. However, the damage is not extensive and complete degradation has not been achieved. The changes in polymer structure were analyzed using Time-domain Nuclear Magnetic Resonance (TD-NMR), High-Temperature Size-Exclusion Chromatography (HT-SEC), Differential Scanning Calorimetry (DSC), and Gas Chromatography with a Flame Ionization Detector (GC-FID). Limited degradation of the LDPE powder was seen in the first 30 days of incubation with the bacteria. Degradation can be seen in the LDPE weight loss percentage, LDPE degradation products in the supernatant, and the decrease in the percentage of amorphous regions (from >47% to 40%). The changes in weight-average molar mass (Mw), number-average molar mass (Mn), and the dispersity ratio (Đ) indicate that the low-molar mass fractions of the LDPE were preferentially degraded. The results here confirmed that LDPE degradation is heavily dependent on the presence of amorphous content and that only the amorphous content was degraded via bacterial enzymatic action.

Biodegradation of low-density polyethylene by mixed fungi composed of Alternaria sp. and Trametes sp. isolated from landfill sites

With the development of industry and modern manufacturing, nondegradable low-density polyethylene (LDPE) has been widely used, posing a rising environmental hazard to natural ecosystems and public health. In this study, we isolated a series of LDPE-degrading fungi from landfill sites and carried out LDPE degradation experiments by combining highly efficient degrading fungi in pairs. The results showed that the mixed microorganisms composed of Alternaria sp. CPEF-1 and Trametes sp. PE2F-4 (H-3 group) had a greater degradation effect on heat-treated LDPE (T-LDPE). After 30 days of inoculation with combination strain H-3, the weight loss rate of the T-LDPE film was approximately 154% higher than that of the untreated LDPE (U-LDPE) film, and the weight loss rate reached 0.66 ± 0.06%. Environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR) were used to further investigate the biodegradation impacts of T-LDPE, including the changes on the surface and depolymerization of the LDPE films during the fungal degradation process. Our findings revealed that the combined fungal treatment is more effective at degrading T-LDPE than the single strain treatment, and it is expected that properly altering the composition of the microbial community can help lessen the detrimental impact of plastics on the environment.

Efficiency of Microorganisms and Effectiveness of Biodegradation Techniques on LDPE Plastics: A Systematic Review

Introduction The aim of the research was to demonstrate the efficiency of microorganisms and the effectiveness of biodegradation techniques on Low-density polyethylene (LDPE) plastics. The research question was: What is the efficiency of LDPE-degrading microorganisms and the effectiveness of biodegradation techniques? Methods The systematic review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Articles were obtained from Scopus, Web of Science (WOS), Embase, and Google Scholar. The DeCS/Mesh search terms were: Low-density polyethylene, efficiency, biodegradation, microbial consortia, fungi, bacteria. Inclusion criteria were: scientific articles that included bacteria, fungi, and microbial consortia reported as LDPE degraders that report the percentage of weight loss; articles published from January 2010 to October 2022, and publications in Spanish and English with open access. Exclusion criteria were: studies that do not report gravimetry, the biodegradation time of LDPE, and the genus or species of the polyethylene-degrading microorganism. Results Out of 483 studies found, 50 were included in this Systematic Review (SR). The most frequent study techniques were scanning electron microscopy (SEM), gravimetry, and fourier transform infrared spectroscopy (FTIR), and in the case of microorganisms, the most studied belonged to the genus Pseudomonas, Bacillus, and Aspergillus. Regarding the isolation place, the most frequent mentioned in the reviewed articles were landfill soil and sanitary landfill soil. The efficiency of LDPE-degrading microorganisms was higher in bacteria such as Enterobacter spp., Pantoea spp., Pseudomonas spp., Escherichia coli, and Bacillus spp., which obtained a range of DE of 9.00-70.00%, 24.00-64%, 1.15 – 61.00%, 45.00%, and 1.5-40% with DT of 4-150, 120, 4-150, 30, and 30-120 days, respectively; in the case of fungi, the main microorganisms are Neopestalotiopsis phangngaensis, Colletotrichum fructicola, and Thyrostroma jaczewskii with efficiencies of 54.34, 48.78, and 46.34%, in 90 days, respectively; and the most efficient microbial consortia were from Enterobacter spp. and Pantoea sp. with 38.00 – 81.00%, in 120 days; and, Pseudomonas protegens, Stenotrophomonas sp., B. vallismortis and Paenibacillus sp. with 55. 00 – 75.00% in 120 days. Conclusions The most efficient microorganisms in LDPE degradation are Enterobacter spp., Pantoea spp., Pseudomonas spp., Escherichia coli, and Bacillus spp.; in fungi Neopestalotiopsis phangngaensis, Colletotrichum fructicola, and Thyrostroma jaczewskii; and in microbial consortia, those formed by Enterobacter spp. and Pantoea sp., and that of P. protegens, Stenotrophomonas sp., B. vallismortis and Paenibacillus sp.; and the most effective techniques used in LDPE biodegradation are SEM, gravimetry, and FTIR.

Enhanced degradation of phototreated recycled and unused low-density polyethylene films by Pleurotus ostreatus.

Polyethylene, one of the most used petroleum-derived polymers, causes serious environmental pollution. The ability of Pleurotus ostreatus to degrade UV-treated and untreated recycled and unused (new) low-density polyethylene (LDPE) films was studied. We determined the fungal biomass production, enzyme production, and enzyme yield. Changes in the chemical structure and surface morphology of the LDPE after fungal growth were analyzed using FTIR spectroscopy and SEM. Functional group indices and contact angles were also evaluated. In general, the highest Lac (6013 U/L), LiP (2432 U/L), MnP (995 U/L) and UP (6671 U/L) activities were observed in irradiated recycled LDPE (IrRPE). The contact angle of all samples was negatively correlated with fermentation time; the smaller the contact angle, the longer the fermentation time, indicating effective biodegradation. The IrRPE samples exhibited the smallest contact angle (49°) at 4 weeks, and the samples were fragmented (into two pieces) at 5 weeks. This fungus could degrade unused (new) LDPE significantly within 6 weeks. The biodegradation of LDPE proceeded faster in recycled than in unused samples, which can be enhanced by exposing LDPE to UV radiation. Enzymatic production during fungal growth suggest that LDPE degradation is initiated by laccase (Lac) followed by lignin peroxidase (LiP), whereas manganese peroxidase (MnP) and unspecific peroxygenase (UP) are involved in the final degradation process. This is the first experimental study on the fungal growth and its main enzymes involved in LDPE biodegradation. This fungus has great promise as a safe, efficient, and environmentally friendly organism capable of degrading LDPE.

Catalytic pyrolysis of plastic waste using activated carbon from cotton waste

This study introduces a novel approach to plastic waste management and energy recovery by synthesizing highly porous activated carbon from an often-overlooked resource, waste cotton fabric (WCF), using H3PO4 as an activating agent. The synthesized waste cotton fabric activated carbon samples (WCF-AC) were utilized as a solid acid catalyst in the catalytic pyrolysis of low-density polyethylene (LDPE), with the aim of converting LDPE into fuel-range hydrocarbons. This research highlights the potential of bio-based waste materials in the synthesis of eco-friendly and cost-effective catalysts for feedstock recycling. The impact of the H3PO4 impregnation ratio and the carbonization/activation temperature on the physicochemical properties of the resulting WCF-AC samples was investigated, providing valuable insights into the optimization of activated carbon production. The catalytic activity of the synthesized WCF-AC samples was evaluated, demonstrating a reduction of 12°C in the LDPE degradation temperature. Furthermore, this work revealed a substantial increase in the formation of carbocyclic compounds, with light aromatics such as benzene, toluene, and xylene constituting up to 43 % of the pyrolysis output. In certain instances, a decrease in heavier hydrocarbons beyond C11 was observed, indicating the selective yield of specific range hydrocarbons. This study underscores the potential of bio-based acid catalysts, such as the synthesized activated carbon presented here, in plastic recycling. The approach adopted in this research aligns with the principles of the circular economy, promoting resource efficiency and sustainability.

Thermoluminescence and ATR-FTIR study of UVC-irradiated low-density polyethylene (LDPE) food packaging

This research aims to study the effects of ultraviolet C (UVC) radiation on low-density polyethylene (LDPE) food packaging. Main objectives include evaluating LDPE degradation and detecting UVC radiation using thermoluminescent dosimeters (TLDs) placed under LDPE samples. Results confirm accurate UVC detection after one hour of exposure, providing a useful tool for optimize food treatment procedures.ATR-FTIR spectroscopy analysis revealed subtle alterations (<8 % transmittance relative) in UVC-irradiated LDPE samples, including possible CH breakage (2910 and 2848 cm−1) and potential CC bond vibrations (1470 cm−1), among others. However, observed variations may stem from LDPE properties rather than entirely from UVC radiation. A comparative study of UVC-induced thermoluminescence (TL) emissions provided insights into various TLDs materials. TL kinetic analysis, using computerised glow curve deconvolution (CGCD) method, unveiled trap charge activation due to UVC exposure, including partial ionization, bleaching effect and photo-transfer (PTTL) processes. LDPE samples amplified UVC-TL responses, revealing intensity differences between the TLDs attributed to the PTTL process, accentuated by the lack of an annealing treatment. Additionally, chemical composition of the TL detectors such as, type, concentration, number, oxidation states and ionic radii of their dopants may influence UVC-TL response. Consequently, TL intensity ratios follow as: GR-200 (LiF: Mg, Cu, P) > TLD-100 (LiF: Ti, Mg) > TLD-400 (CaF2: Mn) > TLD-200 (CaF2: Dy). Thus, GR-200 detects ionizing radiation but cannot distinguish between ionizing and non-ionizing UVC radiation, while TLD-100 has limited effectiveness as a UVC radiation detector. In contrast, TLD-400 is suitable for detecting UVC radiation and TLD-200 emerges as the most favorable UVC detector, showing consistent response levels and minimal PTTL effect placed under the LDPE samples without the need of a thermal annealing treatment that makes the TLD-200 to be reusable in a low-cost measurement protocol.

Advances in plastic mycoremediation: Focus on the isoenzymes of the lignin degradation complex

This study investigates P. ostreatus and A. bisporus biodegradation capacity of low density polyethylene (LDPE) oxidised to simulate environmental weathering. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to analyse the degradation of LDPE treated with fungal cultures. Molecular implications of LDPE degradation by P. ostreatus and A. bisporus were evaluated by Reverse transcription followed by quantitative PCR (qRT-PCR) of lac, mnp and lip genes expression. After 90 days of incubation, FT-IR analysis showed, for both fungal treatments, an increasing in the intensity of peaks related to the asymmetric C-C-O stretching (1160 to 1000 cm−1) and the -OH stretching (3700 to 3200 cm−1) due to the formation of alcohols and carboxylic acid, indicating depolymerisation of LDPE. This was confirmed by the SEM analysis, where a widespread alteration of the surface morphology was observed for treated LDPE fragments. Results revealed that the exposure of P. ostreatus to oxidised LDPE treatment led to a significant increase in the expression of the lac6, lac7, lac9, lac10 and mnp2 genes, while A. bisporus showed an over-expression in lac2 and lac12 genes. The obtained results offer new perspectives for a biotechnological use of P. ostreatus and A. bisporus for plastic bioremediation.

Efficiency of Microorganisms and Effectiveness of Biodegradation Techniques on LDPE Plastics: A Systematic Review.

The aim of the research was to demonstrate the efficiency of microorganisms and the effectiveness of biodegradation techniques on Low-density polyethylene (LDPE) plastics. The research question was: What is the efficiency of LDPE-degrading microorganisms and the effectiveness of biodegradation techniques? The systematic review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Articles were obtained from Scopus, Web of Science (WOS), Embase, and Google Scholar. The DeCS/Mesh search terms were: Low-density polyethylene, efficiency, biodegradation, microbial consortia, fungi, bacteria. Inclusion criteria were: scientific articles that included bacteria, fungi, and microbial consortia reported as LDPE degraders that report the percentage of weight loss; articles published from January 2010 to October 2022, and publications in Spanish and English with open access. Exclusion criteria were: studies that do not report gravimetry, the biodegradation time of LDPE, and the genus or species of the polyethylene-degrading microorganism. Out of 483 studies found, 50 were included in this Systematic Review (SR). The most frequent study techniques were scanning electron microscopy (SEM), gravimetry, and fourier transform infrared spectroscopy (FTIR), and in the case of microorganisms, the most studied belonged to the genus Pseudomonas, Bacillus, and Aspergillus. Regarding the isolation place, the most frequent mentioned in the reviewed articles were landfill soil and sanitary landfill soil. The efficiency of LDPE-degrading microorganisms was higher in bacteria such as Enterobacter spp., Pantoea spp., Pseudomonas spp., Escherichia coli, and Bacillus spp., which obtained a range of DE of 9.00-70.00%, 24.00-64%, 1.15 - 61.00%, 45.00%, and 1.5-40% with DT of 4-150, 120, 4-150, 30, and 30-120 days, respectively; in the case of fungi, the main microorganisms are Neopestalotiopsis phangngaensis, Colletotrichum fructicola, and Thyrostroma jaczewskii with efficiencies of 54.34, 48.78, and 46.34%, in 90 days, respectively; and the most efficient microbial consortia were from Enterobacter spp. and Pantoea sp. with 38.00 - 81.00%, in 120 days; and, Pseudomonas protegens, Stenotrophomonas sp., B. vallismortis and Paenibacillus sp. with 55. 00 - 75.00% in 120 days. The most efficient microorganisms in LDPE degradation are Enterobacter spp., Pantoea spp., Pseudomonas spp., Escherichia coli, and Bacillus spp.; in fungi Neopestalotiopsis phangngaensis, Colletotrichum fructicola, and Thyrostroma jaczewskii; and in microbial consortia, those formed by Enterobacter spp. and Pantoea sp., and that of P. protegens, Stenotrophomonas sp., B. vallismortis and Paenibacillus sp.; and the most effective techniques used in LDPE biodegradation are SEM, gravimetry, and FTIR.

Screening of Different Fungi Strains Gongronella sp. WICC F60 and Cordyceps sp. WICC F61 for Degradation of Low-Density Polyethylene

Over the past decade, polyethylene (PE) products have become increasingly important in several industries. Their biggest concerns are plastic material degradation resistance and environmental longevity. Therefore, this study aims to find fungi that are capable of degrading low-density polyethylene (LDPE) efficiently. This study uses Gongronella sp. WICC F60, and Cordyceps sp., WICC F61. The fungi were grown on potato dextrose agar for 30 days. Following that, fungal colonies were placed in potato dextrose broth for incubation. The LDPE sample was then cultured with the fungal strain in a minimum salt medium with a 10% inoculum. After 30 days of biodegradation testing, the analysis was done. These studies measured LDPE sample weight loss, pH, and fungal biomass. It was observed that the LDPE sample weight loss increased with time until the end of inclubation. Gongronella sp. WICC F60 and Cordyceps sp. WICC F61 were able to degrade LDPE plastic. Both fungi show an increase in LDPE weight loss. However, Cordyceps sp. WICC F61 shows more efficiency in LDPE degradation compared to Gongronella sp. WICC F60. The LDPE weight loss using Gongronella sp. WICC F60 was 1.07%, which is lower than Gongronella sp. WICC F60's LDPE weight reduction of 5.56%.

Biodegradation of low-density polyethylene by the bacterial strains isolated from the dumping site community

Low-density polyethylene (LDPE) is the predominant single-use plastic and rarely decomposes after disposal. The primary objective of this study was to identify potential bacteria capable of degrading LDPE plastic and investigating the biochemical pathways of this process. Bacteria were isolated from soil samples collected from a local garbage dumping site in Thailand and tested on their capability to degrade LDPE plastic. Two of the bacteria isolated from the dumping site, Bacillus sp. AS3 and Sphingobacterium sp. AS8, demonstrated 3.06% and 2.01% (w/w) LDPE plastic weight loss over four weeks, respectively. Analysis by FTIR showed that both bacterial strains degraded the LDPE in the region of 3200–3400 cm−1, which represents the OH group in a commercial LDPE polymer. Bacillus sp. AS3 caused the formation of a new range in the carbonyl group (C=O stretch) and the alcohol, carboxylic acid, esters, and ethers group (–C–O stretch). GC–MS analysis revealed various depolymerized compounds, such as alkane, alcohol, and carboxylic compounds, during LDPE degradation by Bacillus sp. AS3. Bacillus sp. AS3 illustrated esterase activity as 0.608 ± 0.004 U/mL after incubation. The proposed schematic of the LDPE biodegrading pathway by Bacillus sp. AS3 relies on the identification of depolymerized molecules as evidence. This suggests that Bacillus sp. AS3 possesses extracellular enzymes that break down LDPE into smaller molecules through depolymerization. Moreover, the surface of LDPE degraded by Bacillus sp. AS3 and Spingobacterium sp. AS8 was marked by cavities and a rough texture when observed under SEM analysis. This study provides microbial applications to reduce plastic pollution by utilising microorganisms to assimilate plastic waste as a carbon source.

Biodegradation of low-density polyethylene film by two bacteria isolated from plastic debris in coastal beach

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.

Transformation of Single‐Use Plastics into Lighter Hydrocarbons via an Economical Coal Fly Ash based Zeolite Catalyst

AbstractA mixture of zeolite X and A, derived from coal fly ash (CFA), was protonated and utilized as an acid catalyst to decompose single‐use plastics (SUP) waste into lighter hydrocarbons. Low‐density polyethylene (LDPE) was selected as the source of SUP, and this study aimed to investigate the catalytic effects of the protonated CFA‐derived zeolite (H‐XA) as an economical option on the LDPE pyrolysis temperature and output. CFA converted into H‐XA through the conventional alkali fusion, followed by sonication and simplified hydrothermal and protonation processes. The impact of the alkali agent ratio on the resulting product was investigated, and outcomes were evaluated. The product with optimum properties was then selected for investigation in the LDPE pyrolysis studies. Finally, the results were compared with commercial Protonated Zeolite Socony Mobil‐5 (H‐ZSM5) and thermal decomposition without catalysts. Regarding LDPE degradation temperature, H‐XA could lower that by 97 °C compared to thermal degradation, which was almost the same as commercial H‐ZSM5 with 110 °C. The pyrograms obtained through the Pyrolysis‐gas chromatography‐mass spectrometry (Py‐GCMS) analysis indicated the elimination of heavier hydrocarbons in the presence of H‐XA and the product spectra laid in the range of C3 to C9, which was entirely different from the LDPE with hydrocarbons of varying lengths. Moreover, kinetic studies on the LDPE decomposition reactions in this work have revealed that LDPE conversion occurs at a lower activation energy level in the presence of H‐XA, which is comparable to the energy level observed when H‐ZSM5 is used as the catalyst. The synthesis of H‐XA with desirable catalytic activity, such as the ability to lower the LDPE degradation temperature and make lighter hydrocarbons as the pyrolysis output, suggests the great potential of the CFA‐based acid catalyst for use in SUP recycling. This represent a game of waste versus waste within the framework of the circular economy, where the environment is the ultimate winner.

Exploring genetic landscape of low-density polyethylene degradation for sustainable troubleshooting of plastic pollution at landfills

Plastic pollution increases globally due to the high volume of its production and inadequate mismanagement, leading to dumps in landfills affecting terrestrial and aquatic ecosystems. Landfills, as sink for plastics, leach various toxic chemicals and microplastics into the environment. We scrutinized the genetic expression for low-density polyethylene (LDPE) degradation via microorganisms to investigate cell viability and metabolic activities for biodegradation and genetic profiling. Samples were collected from the Pirana waste landfill at Ahmedabad, Gujarat, which is one of the largest and oldest municipal solid waste (MSW) dump sites in Asia. Results analyzed that isolated bacterial culture PN(A)1 (Bacillus cereus) is metabolically active on LDPE as carbon source during starvation conditions when incubated for up to 60 days, which was confirmed via 2,3,5-triphenyl-tetrazolium chloride (TTC) reduction test, reported cell viability and LDPE degradation. Abrasions, surface erosions, and cavity formations were analyzed via scanning electron microscopy (SEM), whereas the breakdown of high molecular polymers converted to low molecules, i.e., depolymerization, was also observed via Fourier-transform infrared (FTIR) spectroscopy over 90 days, along with changes in functional groups of carboxylic acids and aldehyde as well as the formation of polysulfide, aliphatic compounds, aromatic ethers, alcohols, and ether linkages. Further, transcriptomic analysis was performed via DESeq2 analysis to understand key gene expression patterns and pathways involved in LDPE degradation. During the initial phase of LDPE degradation, genes related to biological processes, like membrane transportation, ABC transporters, carbon and lipid metabolism, fatty acid degradation/oxidation, and TCA cycle, are likely to indicate pathways for stress response and molecular functions, like oxidoreductase, catalytic, lyase, transferase, and hydrolase activities were expressed. Interlinking between metabolic pathways indicates biodegradation process that mineralizes LDPE during subsequent incubation days. These pathways can be targeted for increasing the efficiency of LDPE degradation using microbes in future studies. Thus, considering microbial-mediated biodegradation as practical, eco-friendly, and low-cost alternatives, healthy biomes can degrade polymers in natural environments explored by understanding the genetic and enzymatic expression, connecting their role in the process to the likely metabolic pathways involved, thereby increasing the rate of their biodegradation.

Degradation of low-density polyethylene by the bacterium Rhodococcus sp. C-2 isolated from seawater

Low-density polyethylene (LDPE), which accounts for 20% of the global plastic production, is discharged in great quantities into the ocean, threatening marine life and ecosystems. Marine microorganisms have previously been reported to degrade LDPE plastics; however, the exploration of strains and enzymes that degrade LDPE is still limited. Here, an LDPE-degrading bacterium was isolated from seawater of the Changjiang Estuary, China and identified as Rhodococcus sp. C-2, the relative abundance of which was dramatically enhanced during PE-degrading microbial enrichment. The strain C-2 exhibited the degradation of LDPE films, leading to their morphological deterioration, reduced hydrophobicity and tensile strength, weight loss, as well as the formation of oxygen-containing functional groups in short-chain products. Sixteen bacterial enzymes potentially involved in LDPE degradation were screened using genomic, transcriptomic, and degradation product analyses. Thereinto, the glutathione peroxidase GPx with exposed active sites catalyzed the LDPE depolymerization with the cooperation of its dissociated superoxide anion radicals. Furthermore, an LDPE degradation model involving multiple enzymes was proposed. The present study identifies a novel PE-degrading enzyme (PEase) for polyethylene bioremediation and promotes the understanding of LDPE degradation.

Biodegradation of LDPE (low density polyethylene) using bacterial strain

The applications of polyethylene are enormous and they are popular because of their relatively low cost, lack of difficulty in manufacture, adaptability and durability. In the past decade, the increase in the utilization of plastics and the accumulation of polyethylene in the environment all around the globe has drawn the attention of environmentalists and scientists. The plastic materials are commonly derived from petrochemicals extracted from coal and natural gas. They are produced in a wide range in synthetic, semi synthetic organic polymers. The degradation of LDPE film was determined by residual dry weight loss of the LDPE films. The potent strain showed 42.5% degradation ability in 90 d. Degradation of LDPE results in the breakdown of the polymer backbone chain producing CO2 which was checked by gravimetric analysis. Enzyme kinetic studies showed the production of three ligninolytic extracellular enzymes- lignin, laccase and manganese peroxidase by bacterial strain AJ01 in LDPE degradation. Degradation of LDPE strips followed first order kinetics model with a rate constant (R2) of 0.9783 d-1. Estimation of protein from post treated LDPE using bacterial isolate showed a total concentration of 0.440mg/0.1mL and 0.703mg/0.2mL. LDPE degradation was confirmed by using analytical techniques such as SEM which showed changes in the surface topology of LDPE strips and FTIR analysis showed changes in complex chemical structure of LDPE post 90 d of degradation using microorganisms thereby reducing carbonyl index (CI) value.

Wood decay fungi show enhanced biodeterioration of low-density polyethylene in the absence of wood in culture media.

The involvement of microorganisms in low-density polyethylene (LDPE) degradation is widely studied across the globe. Even though soil, landfills, and garbage dumps are reported to be promising niches for such organisms, recently the involvement of wood decay fungi in polyethylene degradation is highlighted. In light of this, 50 fungal samples isolated from decaying hardwoods were assessed for their wood degradation ability and for their depolymerization enzymatic activities. For the LDPE deterioration assay, 22 fungal isolates having wood decay ability and de-polymerization enzymatic activities were selected. Fungal cultures with LDPE sheets (2 cm x 10 cm x 37.5 μm) were incubated in the presence and in the absence of wood as the carbon source (C) for 45 days. Degradation was measured by weight loss, changes in tensile properties, reduction in contact angle, changes of functional groups in Fourier-transform infrared spectroscopy, Scanning electron microscopic imaging, and CO2 evolution by strum test. Among the isolates incubated in the absence of wood, Phlebiopsis flavidoalba out-performed the other fungal species showing the highest percentage of weight reduction (23.68 ± 0.34%), and the lowest contact angle (64.28° ± 5.01). Biodegradation of LDPE by P. flavidoalba was further supported by 46.79 ± 0.67% of the mass loss, and 3.07 ± 0.13% of CO2 emission (mg/L) in the strum test. The most striking feature of the experiment was that all the isolates showed elevated degradation of LDPE in the absence of wood than that in the presence of wood. It is clear that in the absence of a preferred C source, wood decay fungi thrive to utilize any available C source (LDPE in this case) showing the metabolic adaptability of fungi to survive under stressful conditions. A potential mechanism for LDPE degradation is also proposed.

Degradation of LDPE Using the Winogradsky Column Containing Otteri Dumpsite Soil: Prediction of Mechanism and Metabolites Determination

Background of the Research: Plastic pollution has taken over the world. Toxicity of the plastics and other pollutants is enhanced due to the formation of microplastics and nano-plastics that attract Persistent Organic Pollutants (POPs). The need for the treatment of plastic waste in the current scenario led to the rise of various treatment processes. Biodegradation, an eco-friendly approach to eliminate plastics urged to discover plastic-utilizing bacteria and plastic-eating worms. Bacterial degradation of plastics has been extensively studied utilizing the entire microbial community. Hence, the current research focuses on the biodegradation of Low-Density polyethylene (LDPE) using Winogradsky Column constructed using dump yard soil. LDPE degradation was determined using FTIR and GC-MS analysis, which is used to analyze the degradation mechanism of LDPE. Methods: Sample Collection and Column Construction: The soil samples collected from the Chennai dump yard were used to construct Winogradsky columns. The column with LDPE and enrichment sources is used to study LDPE degradation. Analysis of LDPE Degradation: The LDPE sheet after incubation was washed with surfactant and ethanol. The dried sheet was analyzed for weight loss and the metabolites were identified using GC-MS analysis. The GC-MS chromatogram was used to determine the pattern of degradation by the microbial community in the dump yard soil. Results: The mass spectral analysis of GC peaks has been carried out using the electron ionization method, and ions were detected using positive ions scanning mode. The GC peaks appeared at 22.532 and 23.117 min in the control LDPE sheet, which was found to be nonadecane and octacosane, whereas, in the treated LDPE sheet, the GC peaks appeared at 22.467 and 23.062 min. The fragmentation pattern indicates the loss of m/z 14, which confirms the loss of methylene (-CH2-) fragments in alkyl chains. The difference in retention time could be correlated with the increase of CH2 in the alkyl chain length and molecular weight. Higher molecular weight alkanes, such as C16, C18, and C20 above appeared at higher retention times. The presence of longer alkyl chains indicates the LDPE polymer chains. The treated LDPE sample has been analyzed, and the fragmentation pattern indicates the presence of aliphatic chains of C16 or C18. Conclusion: The current study provides an efficient method to utilize the microbial community as a whole to degrade LDPE. The degradation mechanism of LDPE was determined using GC-MS analysis. The high molecular weight polymeric chain was degraded to small chains, and the formation of alcohol indicates the occurrence of terminal oxidation. Hence, this confirms the degradation of LDPE by the microbiome present in the dump yard soil.

Cladosporium cladosporioides (strain Clc/1): a candidate for low-density polyethylene degradation

BackgroundPlastic is one of the most widely used materials worldwide in various fields, including packaging and agriculture. Its large quantities require proper disposal and for this reason more and more attention is paid to the issue of degrading plastic. Thanks to the production of non-specific enzymes, fungi are able to attack complex and recalcitrant xenobiotics such as plastics. In recent years, several spectroscopic methods were used to study the plastic degradation ability of different fungal species. Among these, Fourier transform infrared (FT-IR) and FT-Raman spectroscopy techniques are the most used. Surface-enhanced Raman scattering (SERS) spectroscopy is a powerful technique which uses metal nanoparticles (NPs) to enhance the Raman signal of molecules adsorbed on the NPs surface. In this work, the isolation of different fungi from field-collected plastic debris and the ability of these isolates to growth and colonizing the low-density polyethylene (LDPE) were explored by using scanning electron microscope (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and SERS spectroscopies.ResultsForty-seven fungal isolates belonging to 10 genera were obtained; among them only 11 were able to grow and colonize the LDPE film. However, after 90 days trial, only one isolate of Cladosporium cladosporioides (Clc/1) was able to carry out the initial degradation of the LDPE film. In particular, based on SEM observations, small cavities and depressed areas of circular shape were visible in the treated samples. Additionally, ATR-FTIR, normal Raman and SERS analyses supported the structural changes observed via SEM. Notably, ATR-FTIR and normal Raman spectra showed a significant decrease in the relative intensity of the methylene group bands. Similarly, the SERS spectra of LDPE after the fungal attack, confirmed the decrease of methylene groups bands and the appearance of other bands referring to LDPE polyphenolic admixtures.ConclusionsThese results suggest that Cladosporium cladosporioides Clc/1 is able to carry out an initial degradation of LDPE. Moreover, combining ATR-FTIR, Raman and SERS spectroscopies with SEM observations, the early stages of LDPE degradation can be explored without any sample pretreatment.Graphical

Multivariate analysis of enriched landfill soil consortia provide insight on the community structural perturbation and functioning during low-density polyethylene degradation

Plastic-enriched sites like landfills have immense potential for discovery of microbial consortia that can efficiently degrade plastics. In this study, we used a combination of culture enrichment, high-throughput PacBio sequencing of 16 S rRNA and the ITS gene, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) to examine the compositional and diversity perturbations of bacterial and fungal consortia from landfill soils and their impact on low-density polyethylene (LDPE) film biodegradation over a 90-day period. Results showed that enrichment cultures effectively utilized LDPE as a carbon source for cellular growth, resulting in significant weight reduction (22.4% and 55.6%) in the films. SEM analysis revealed marked changes in the micrometric surface characteristics (cracks, fissures, and erosion) and biofilm formation in LDPE films. FTIR analyses suggested structural and functional group modification related to C-H (2831–2943 cm⁻¹), and CH₂ (1400 cm⁻¹) stretching, CO and CC (680–950 cm⁻¹) scission, and CO incorporation (3320–3500 cm⁻¹) into the carbon backbone, indicative of LDPE polymer biodegradation. Enrichment cultures had lower diversity and richness of microbial taxa compared to soil samples, with LDPE as a carbon source having a direct influence on the structure and functioning of the microbial consortia. A total of 26 bacterial and 12 fungal OTU exhibiting high relative abundance and significant associations (IndVal > 0.7, q < 0.05) were identified in the enrichment culture. Bacterial taxa such as unclassified Parvibaculum FJ375498, Achromobacter xylosoxidans, unclassified Chitinophagaceae PAC002331, unclassified Paludisphaera and unclassified Comamonas JX898122, and six fungal species (Galactomyces candidus, Trichosporon chiropterorum, Aspergillus fumigatus, Penicillium chalabudae, Talaromyces thailandensis, and Penicillium citreosulfuratum) were identified as the putative LDPE degraders in the enrichment microbial consortium cultures. PICRUSt2 metagenomic functional profiling of taxonomic bacterial taxa abundances in both landfill soil and enrichment microbial consortia also revealed differential enrichment of energy production, stress tolerance, surface attachment and motility pathways, and xenobiotic degrading enzymes important for biofilm formation and hydrolytic/oxidative LDPE biodegradation. The findings shed light on the composition and structural changes in landfill soil microbial consortia during enrichment with LDPE as a carbon source and suggest novel LDPE-degrading bacterial and fungal taxa that could be explored for management of polyethylene pollution.

Biodegradation of Low Density Polyethylene by the Fungus Cladosporium sp. Recovered from a Landfill Site.

Low density polyethylene (LDPE) has been widely used commercially for decades; however, as a non-degradable material, its continuous accumulation has contributed to serious environmental issues. A fungal strain, Cladosporium sp. CPEF-6 exhibiting a significant growth advantage on MSM-LDPE (minimal salt medium), was isolated and selected for biodegradation analysis. LDPE biodegradation was analyzed by weight loss percent, change in pH during fungal growth, environmental scanning electron microscopy (ESEM), and Fourier transformed infrared spectroscopy (FTIR). Inoculation with the strain Cladosporium sp. CPEF-6 resulted in a 0.30 ± 0.06% decrease in the weight of untreated LDPE (U-LDPE). After heat treatment (T-LDPE), the weight loss of LDPE increased significantly and reached 0.43 ± 0.01% after 30 days of culture. The pH of the medium was measured during LDPE degradation to assess the environmental changes caused by enzymes and organic acids secreted by the fungus. The fungal degradation of LDPE sheets was characterized by ESEM analysis of topographical alterations, such as cracks, pits, voids, and roughness. FTIR analysis of U-LDPE and T-LDPE revealed the appearance of novel functional groups associated with hydrocarbon biodegradation as well as changes in the polymer carbon chain, confirming the depolymerization of LDPE. This is the first report demonstrating the capacity of Cladosporium sp. to degrade LDPE, with the expectation that this finding can be used to ameliorate the negative impact of plastics on the environment.