Biodegradation Of Low Density Polyethylene Research Articles

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 Low Density Polyethylene (LDPE) using marine bacteria isolated from tropical beaches of megacity Mumbai

Biodegradation of Low Density Polyethylene (LDPE) using marine bacteria isolated from tropical beaches of megacity Mumbai

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.

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.

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.

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

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.

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.

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 (LDPE) by Paenibacillus Sp. and Serratia Sp. isolated from marine soil sample

Low Density Polyethylene (LDPE) is recalcitrant and poses serious threats to our environment. The present study explored the LDPE biodegradation potential of aerobic bacteria enriched from offshore of RK beach Visakhapatnam. These isolates were specifically enriched in MSAM medium which contains LDPE as the source of carbon and energy for the growth. Six strains were isolated; among these S-6 & S-2 are the most potent strains which were attributed to the degrading ability. The phenotypic fingerprint such as Gen III biolog was used to identify the LDPE degrading S-6 as Paenibacillus sp. and S-2 as Serratia sp. respectively. Gen III Microlog, a phenotypic microarray; have been used for analysis of relative capabilities for substrate utilization of S-6 and S- 2 strains. The contact time of 72 h, temperature of 37 °C, pH of 7.1, inoculum volume 4% v/v, and weight of LDPE films 0.030 g were found to be optimal conditions for biodegradation of LDPE. Efficiency of these microbes (Paenibacillus sp. and Serratia sp) in degradation of LDPE was studied by percent weight reduction during a time period of 35 days. The Paenibacillus sps. proved to be most efficient with a weight loss of 22.46% compared to Serratia sps. with a weight loss of 9.5%. These bacterial species are capable of utilising LDPE as the sole carbon and energy source.

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.

Biodegradation of low-density polyethylene (LDPE) through application of indigenous strain Alcaligenes faecalis ISJ128.

The resiliency of plastic products against microbial degradation in natural environment often creates devastating changes for humans, plants, and animals on the earth's surface. Biodegradation of plastics using indigenous bacteria may serve as a critical approach to overcome this resulting environmental stress. In the present work, a polyethylene degrading bacterium Alcaligenes faecalis strain ISJ128 (Accession No. MK968769) was isolated from partially degraded polyethylene film buried in the soil at plastic waste disposal site. The biodegradation studies were conducted by employing various methods such as hydrophobicity assessment of the strain ISJ128, measurement of viability and total protein content of bacterial biofilm attached to the polyethylene surface. The proliferation of bacterial cells on polyethylene film, as indicated by high growth response in terms of protein content (85.50µgmL-1) and viability (1010CFUmL-1), proposed reasonable suitability of our strain A. faecalis ISJ128 toward polyethylene degradation. The results of biodegradation assay revealed significant degradation (10.40%) of polyethylene film within a short period of time (i.e., 60days), whereas no signs of degradation were seen in control PE film. A. faecalis strain ISJ128 also demonstrated a removal rate of 0.0018day-1 along with half-life of 462days. The scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy studies not only displayed changes on polyethylene surface but also altered level of intensity of functional groups and an increase in the carbonyl indexes justifying the degradation of polyethylene film due to bacterial activity. In addition, the secondary structure prediction (M fold software) of 16SrDNA proved the stable nature of the bacterial strain, thereby reflecting the profound scope of A. faecalis strain ISJ128 as a potential degrader for the eco-friendly disposal of polyethylene waste. Schematic representation of methodology.

Influence of ultraviolet and chemical treatment on the biodegradation of low-density polyethylene and high-density polyethylene by Cephalosporium strain.

In the present work, the potential of Cephalosporium strain in degrading the pre-treated (ultraviolet irradiation followed by nitric acid treatment) low-density polyethylene and high-density polyethylene films was investigated. Our observations revealed a significant weight reduction of 24.53 ± 0.73% and 18.22 ± 0.31% in pre-treated low-density polyethylene and high-density polyethylene films respectively, after 56days of incubation with the Cephalosporium strain. Changes in the physicochemical properties of the mineral salt medium (MSM) were studied to assess the extent of biodegradation. The pH of the MSM decreased gradually during the incubation period, whereas its total dissolved solids and conductivity values increased steadily. Fourier transform infrared spectroscopy (FTIR) indicated the formation of hydroxyl and C = C groups in biodegraded low-density polyethylene films, while in the case of biodegraded high-density polyethylene films it indicated the [Formula: see text]CH2 stretching. Furthermore, the thermogravimetric analysis (TGA) revealed an enhancement in the thermal stabilities of both the LDPE and HDPE films post the biodegradation. Modifications in the polymer surface morphologies after UV irradiation, chemical treatment, and biodegradation steps were visualized via scanning electron microscopy (SEM) analysis. All our observations confirm the ability of the Cephalosporium strain in biodegrading the pre-treated LDPE and HDPE films.

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.

Biodegradation of low-density polyethylene film/plasticized cassava starch blends with central composite design for optimal environmental pollution control

The present study investigated the optimization of biodegradation parameters of low-density polyethylene (LDPE) film/plasticized cassava starch (PCS) blends for optimal environmental pollution control. Six sample blends, 0–50 wt.% of PCS were produced at the ratios of (0:100, 1:9, 1:4, 1:2.3, 1:1.5 & 1:1) by varying composition of LDPE film and PCS through solvent casting method. Central Composite Design (CCD) of Response surface methodology (RSM) was utilized to optimize the process parameters of concentration and time that resulted in percentage weight loss, elongation at break, tensile and tear strengths (response). Analysis of variance (ANOVA) revealed that the equation obtained for biodegradation is quadratic and hence significant for the process. Addition of 50 wt.% of PCS to the blend reduced the tensile strength from 15.08 – 5.25 MPa, tear strengths from 164.13 – 82.67 N/mm and elongation at break from 18.93 – 9.32 mm, while water absorption was typical of Fickian behavior. Optimal biodegradation of 12.59% at parametric conditions of 43 wt.% PCS and 66 days via RSM was achieved which conforms with a minimum requirement of 12% degradation at 2 months soil burial by NF U52–001 standard. The produced films were characterized by Furrier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analysis. From the statistical analysis, the optimum biodegradation (12.59%) was achieved at 43 wt.% PCS concentration. As a result, the optimized conditions obtained from this study propose that a 43 wt.% optimal concentration of bio-filler is required for excellent mechanical properties with improved biodegradation for sustainable environmental pollution control.

Exploitation of bacterial strains for microplastics (LDPE) biodegradation

Plastic waste (microplastics) is one of the primary sources of environmental pollutants, serving as a reservoir for them. In this study, previously isolated and screened polymer-degrading bacteria (B. subtilis V8, P. aminophilusB1 4-, P. putida C 2 5, P. aeruginosa V1, and A. calcoaceticus V4) were utilised to examine the biodegradation of LDPE (low-density polyethylene) microplastics. Response surface methodology (RSM) was used to optimize the physicochemical growth parameters (pH, temperature, and ammonium sulphate concentration). By using the polyphasic approach, including CO2 estimation, weight loss analysis, scanning electron microscopy (SEM), fourier transform infrared (FT-IR) spectroscopy, and electrical conductivities examine the plastic biodegradability. After four months, all biodegradable plastic samples were evaluated. When compared to the other tested cultures, P. aeruginosa V1 showed the most significant degradation (CO2evolution of 8.86 g.l-l and percentage weight loss of 18.21 %) with increased electrical conductivity, followed by B. subtilis V8 (CO2 evolution of 8.10 g.l-l and percentage weight loss of 16.12 %), A. calcoaceticus V4 (CO2 evolution of 7.21 g.l-l and percentage weight loss of 15.44 %), P. putida C 2-5 (CO2 evolution of 5.76 g.l-l and percentage weight loss of 13.30 %), and P. aminophilus B1 4- (CO2 evolution of 5.62 g.l-l and percentage weight loss of 11.72 %). The deteriorated materials' exterior modifications (surface alteration) were also examined using SEM analysis, and the chemical bonding alterations (bond vibration-bending) were determined using FT-IR spectroscopy.

Degradation of low density polyethylene by Bacillus species

Since its invention, polyethylene (PE) has brought many conveniences to human production and life. In recent years, however, environmental pollution and threats to human health caused by insufficient PE recycling have attracted widespread attention. Biodegradation is a potential solution for preventing PE pollution. In this study, Bacillus subtilis and Bacillus licheniformis, which are widespread in the environment, were examined for their PE degradation abilities. Biodegradation of low-density polyethylene (LDPE) was assessed by weight loss, Fourier transform infrared spectroscopy (FTIR), and high performance liquid chromatography (HPLC) analyses. Weight losses of 3.49% and 2.83% were observed for samples exposed to strains B. subtilis ATCC6051 and B. licheniformis ATCC14580 for 30 days. Optical microscopy revealed obvious structural changes, such as cracks, pits, and roughness, on the surfaces of the microorganism-exposed LDPE sheets. Oxidation of the LDPE sheet surfaces was also demonstrated by the FTIR-based observation of carbon-unsaturated, –OH, –NO, –C=C, and –C–O bonds. These results support the notion that B. subtilis ATCC6051 and B. licheniformis ATCC14580 can degrade PE and could potentially be used as PE-biodegrading microorganisms. Further research is needed to examine potential relevant degradation mechanisms, such as those involving key enzymes.

Soil as a source of polyethylene degrading microorganisms

The presence of low-density polyethylene (LDPE) degrading microorganisms was found in the soils of the Republic of Moldova. Under standard soil conditions the LDPE biodegradation was relatively slow, implying the possibility of long-term negative environmental impacts from soil pollution by LDPE. It was observed that the biodegradation rates could be substantially improved by adding glucose into the soil (0,5%). LDPE biodegradation rates depended on the soil type and on the presence or absence of increased environmental stress for the soil microbial biomass. The highest biodegradation rate was observed in the case of a virgin forest soil sampled from the Orhei region: on day 41 after adding glucose into the soil with introduced LDPE the soil microbial biomass was 6.1% higher than in the control without LDPE, while the extent of LDPE degradation reached 2.3%.