Surface adhesion and multienzyme pathways drive low-density polyethylene microplastic biodegradation by soil bacteria

Microplastics represent an emerging threat to aquatic environments and organisms, as they infiltrate water systems, are ingested by marine species, and cause physical harm, endocrine disruption, and bioaccumulation up the food chain, potentially impacting biodiversity and human health. Aquatic ecosystems face considerable harm from microplastic pollution because fish in the early developmental stages, including embryos, larvae, and juveniles, are more susceptible due to their immature physiological and detoxification systems. This review aims to comprehensively explore the impacts of microplastics on the early life stages of fish. Aquatic environments receive primary and secondary MPs from urban runoff and industrial waste, together with degraded plastics, which affect fish embryos and larvae via direct ingestion, surface adhesion, and trophic transmission pathways. The physical impact of MPs causes digestive tract blockages that reduce hatching success and create developmental problems in fish organs, but chemical toxicity develops from plasticizers, heavy metal leaching, and pollutant adsorption, which causes oxidative stress, endocrine disruption, and metabolic dysfunction. Survival rates decrease because exposure causes fish to perform poorly during swimming activities and make limited efforts to avoid predators. The small dimensions and high chemical reactivity of MPs increase their bioavailability, which promotes tissue penetration and leads to accumulation at different levels of the food chain. This comprehensive review emphasizes that we need to establish uniform detection protocols, long-term exposure research, and effective strategies to control MP pollution. The resolution of these difficulties remains essential for protecting fish populations, as well as for protecting biodiversity and minimizing seafood contamination risks to human health.

Periodontitis, a leading cause of adult tooth loss and linked to various systemic diseases, is promoted by subgingival plaque biofilms, with Streptococci as early colonizers responsible for surface adhesion. Current studies of Streptococci adhesion have focused on bacteria surface adhesins with acquired protein membranes on the tooth surface, yet no critical proteins with implications for the overall early adhesion of subgingival plaque have been reported. Here, we identified that the “Barrel-like adhesion domain” of streptococcal EF-Tu facilitates cell-surface attachment, promotes biofilm formation, and contributes to the development of periodontitis. In the adherent state, EF-Tu is transported from the cytoplasm to the cell surface through membrane vesicles. Furthermore, we first found that simeprevir, an FDA-approved drug, binds to the “Barrel-like adhesion domain” of EF-Tu and effectively inhibits the protein’s surface adhesion and secretory pathways. Simeprevir showed the ability to inhibit dental plaque formation and provided prevention and treatments for periodontitis.

Once dispersed in water, plastic materials become promptly colonized by biofilm-forming microorganisms, commonly known as plastisphere. By combining DNA sequencing and Confocal Laser Scanning Microscopy (CLSM), we investigated the plastisphere colonization patterns following exposure to natural lake waters (up to 77 days) of either petrochemical or biodegradable plastic materials (low density polyethylene - LDPE, polyethylene terephthalate - PET, polylactic acid - PLA, and the starch-based MaterBi® - Mb) in comparison to planktonic community composition. Chemical composition, water wettability, and morphology of plastic surfaces were evaluated, through Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), and static contact angle analysis, to assess the possible effects of microbial colonization and biodegradation activity. The phylogenetic composition of plastisphere and planktonic communities was notably different. Pioneering microbial colonisers, likely selected from lake waters, were found associated with all plastic materials, along with a core of more than 30 abundant bacterial families associated with all polymers. The different plastic materials, either derived from petrochemical hydrocarbons (i.e., LDPE and PET) or biodegradable (PLA and Mb), were used by opportunistic aquatic microorganisms as adhesion surfaces rather than carbon sources. The Mb-associated microorganisms (i.e. mostly members of the family Burkholderiaceae) were likely able to degrade the starch residues on the polymer surfaces, although the Mb matrix maintained its original chemical structure and morphology. Overall, our findings provide insights into the complex interactions between aquatic microorganisms and plastic materials found in lake waters, highlighting the importance of understanding the plastisphere dynamics to better manage the fate of plastic debris in the environment.

Plastic has high potency to become material that much threats human living in this earth, because made from chemical which cannot degraded by microbes in environment. The successful production and marketing of biodegradable plastics will help alleviate the problem of environmental pollution. One of biodegradable plastic that used in our live is polyethylene. This research reveals that local microbes capable to degrading of polyethylene. Biodegradation test was carried out by using bacteria in soil which was obtained from Gunung Tugel disposal center, Banyumas regency. Kind of polyethylene is LDPE (Low Density Polyethylene) which was obtained from Setiakawan Plastic Factory, Kalibogor, Purwokerto formed to thin film. Characterization of the polyethylene used weight loss percentage method, melting point determination and FTIR. Soil bacteria isolated from Gunung Tugel disposal center, Banyumas regency, obtained 5 single colonies, which coded GT. Bacteria isolate which have highest activity in degrading polyethylene was GT 3, with increasing the time of incubation. Weight loss percentage up to 2.33% in 1 month. Melting point of polyethylene after biodegradation was decreased that initially 210-220 °C into 210-213 °C. FTIR spectrophotometer result of polyethylene after biodegradation showed intensity for methylene and methyl cluster was decreased.

The online version contains supplementary material available at 10.1007/s13205-020-02592-9.

Surface adhesion between ceramic injection molding feedstocks and processing tools

Duty cycle dependent chemical structure and wettability of RF pulsed plasma copolymers of acrylic acid and octafluorocyclobutane

Soil bacterial community and metabolism showed a more sensitive response to PBAT biodegradable mulch residues than that of LDPE mulch residues

Polyethylene's extreme non-biodegradability has made it a major environmental contaminant, and numerous researchers are working to find a means to break it down. Here, we've attempted to use soil bacteria that were isolated from plastic disposal sites to break down plastic in this research. Polystyrene (PS), Polyethylene terephthalate (PET), High-density polyethylene (HDPE), and Low-density polyethylene (LDPE) are common plastic polymers that provide serious environmental problems because they don't break down naturally. Soil samples from plastic disposal sites in Mohali, Chandigarh, and Hoshiarpur were examined in this study to look for microbes that could break down the plastics. Bacteria were isolated after a series of transfers using carbon-free basal media (CFBM) enhanced with plastic pieces. Through morphological and biochemical characterization, three strains of Gram-positive bacteria were identified: Propionibacterium acnes, Staphylococcus sp., and Paenibacillus sp. By measuring weight loss over a five-month period, biodegradation experiments revealed that P. acnes showed no degradation, Staphylococcus sp. achieved 24% degradation (from 50 mg to 42 mg), and Paenibacillus sp. destroyed LDPE by 16%. These results support earlier research showing that Paenibacillus and Staphylococcus have the ability to degrade plastic, and they demonstrate that P. acnes does not degrade polymers despite its ability to build biofilms. The outcomes validate the possible use of these bacterial isolates in plastic waste management based on biodegradation.

The use of polymers in all aspects of daily life is increasing considerably, so there is high demand for polymers with specific properties. Polymers with antibacterial properties are highly needed in the food and medical industries. Low-density polyethylene (LDPE) is widely used in various industries, especially in food packaging, because it has suitable mechanical and safety properties. Nevertheless, the hydrophobicity of its surface makes it vulnerable to microbial attack and culturing. To enhance antimicrobial activity, a progressive surface modification of LDPE using the antimicrobial agent grafting process was applied. LDPE was first exposed to nonthermal radio-frequency (RF) plasma treatment to activate its surface. This led to the creation of reactive species on the LDPE surface, resulting in the ability to graft antibacterial agents, such as ascorbic acid (ASA), commonly known as vitamin C. ASA is a well-known antioxidant that is used as a food preservative, is essential to biological systems, and is found to be reactive against a number of microorganisms and bacteria. The antimicrobial effect of grafted LDPE with ASA was tested against two strong kinds of bacteria, namely, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), with positive results. Surface analyses were performed thoroughly using contact angle measurements and peel tests to measure the wettability or surface free energy and adhesion properties after each modification step. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the surface morphology or topography changes of LDPE caused by plasma treatment and ASA grafting. Surface chemistry was studied by measuring the functional groups and elements introduced to the surface after plasma treatment and ASA grafting, using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). These results showed wettability, adhesion, and roughness changes in the LDPE surface after plasma treatment, as well as after ASA grafting. This is a positive indicator of the ability of ASA to be grafted onto polymeric materials using plasma pretreatment, resulting in enhanced antibacterial activity.

Low‐density polyethylene (LDPE) modified by atmospheric dielectric surface barrier discharge plasma in oxygen was investigated to improve surface properties and adhesion of LDPE to more polar polymers. The process of plasma modification was investigated using several methods—surface energy measurements, Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR‐ATR), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The surface energy of LDPE increased significantly after activation by oxygen barrier plasma even at very short time of modification. The FTIR‐ATR spectra manifested the presence of carbonyl functional groups on the surface of polymer pre‐treated by oxygen barrier plasma. It was shown by SEM, and AFM, that the topography of modified LDPE was significantly changed and the surface of modified polymer exhibited higher roughness in comparison with unmodified polymer. The surface energy of treated LDPE diminished in the course of ageing especially during the first 10 days after modification by barrier plasma. Hydrophilicity of the modified LDPE surface was stabilized by photochemical post‐functionalization with 2,2,6,6‐tetramethylpiperidin‐4‐yl‐diazoacetate. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Recent advances in polymer surface science have been largely due to the well-recognized need to control the surface properties of polymer materials and the development of sophisticated surface-specific characterization techniques. While the majority of the research and development efforts have been mostly focused on bulk properties, demands for low surface energy polymers exhibiting low adhesion (friction) and good biocompatibility have generated significant interest on physical and chemical properties of polymer surfaces. For instance, ultra-high molecular weight polyethylene (UHMWPE) and low-density polyethylene (LDPE) are the principal materials used to replace damaged cartilage in total joint arthroplasty and to fabricate catheters for balloon angioplasty, respectively. Therefore, surface treatments to improve adhesion and biocompatibility of these polymer surfaces are of paramount importance in the medical field. Radio frequency (rf) plasma-enhanced surface modification (PESM) provides an effective means for altering the biochemical properties of polymer surfaces without affecting the bulk behavior. The main process steps of PESM are discussed here and its effectiveness is demonstrated by representative friction coefficient, contact angle, and biocompatibility results for LDPE and UHMWPE surfaces treated with various plasma chemistries.

The Am1010 cell line was previously established from a metastatic deposit in an arm muscle from a patient with lung adenocarcinoma who had undergone four cycles of chemotherapy with cisplatin and taxol. Am1010 cells were labeled with red fluorescent protein or green fluorescent protein. A total of eight sublines were isolated following in vitro exposure to cisplatin or taxol. The sublines differed with regard to their adhesion and proliferation properties, with certain sublines exhibiting an increased proliferation rate and/or decreased surface adhesion. Gene expression assays demonstrated that tenascin C; cyclin D1; collagen, type 1, α2; integrin α1; related RAS viral (r-ras) oncogene homolog 2; platelet-derived growth factor C; and Src homolog 2 domain containing in the focal adhesion pathway, and intercellular adhesion molecule 1, F11 receptor, claudin 7 and cadherin 1 in the cell adhesion pathway, varied in expression among the sublines. The results of the present study suggested that drug exposure may alter the aggressiveness and metastatic potential of cancer cells, which has important implications for cancer chemotherapy.

IFN-alpha influences the recirculation and growth of normal and malignant B lymphocytes, although the mechanisms involved are not currently known. Lymphocyte recirculation is fundamentally dependent on cell-to-cell interactions that are mediated by cell surface adhesion molecules. In this report, we examined the relationship between the effect of IFN-alpha on cell-to-cell adhesion processes and induction of the Leu-13 cell surface protein in established human Daudi B lymphoid cell lines that are either sensitive or resistant to the antiproliferative activity of IFN-alpha. IFN-alpha directly triggered homotypic adhesion of IFN-sensitive Daudi B cells in a time- and dose-dependent manner. In contrast, IFN-alpha had no effect on the cell-to-cell adhesion of IFN-resistant Daudi B cells. The capacity of IFN-alpha to trigger homotypic aggregation correlated directly with the level of induction of the cell surface protein Leu-13 and could be potentiated by anti-Leu-13 mAb. Other cytokines also known to influence the proliferation, differentiation, or recirculation of B lymphocytes such as IFN-gamma, IL-2, IL-4, IL-6, TNF-alpha, and low molecular weight B cell growth factor did not induce either Leu-13 expression or homotypic aggregation of Daudi B cells. The adhesion pathway triggered by the IFN-inducible protein Leu-13 required metabolic energy and an intact cytoskeleton but was not dependent on: 1) new protein synthesis; 2) protein kinase C, protein kinase A, or tyrosine kinase activities; or 3) the function of known adhesion molecules including LFA-1, ICAM-1, CD44, or VLA-4. Taken together, these studies demonstrate a fundamental role for IFN-alpha and the IFN-inducible protein Leu-13 in regulating a novel homotypic adhesion pathway in B lymphocytes, and provide insight into the possible mechanisms by which IFN-alpha regulates biologic processes including recirculation.

Atmospheric plasma torch treatment of polyethylene/boron composites: Effect on thermal stability