Biodegradation of petroleum based and bio-based plastics: approaches to increase the rate of biodegradation

From plankton to fish: The multifaceted threat of microplastics in freshwater environments

The detrimental impact of emerging pollutants, specifically microplastics (MPs), on the ecological environment are receiving increasing attention. Freshwater ecosystems serve as both repositories for terrestrial microplastic (MP) sources and conduits for their subsequent entry into marine environments. Consequently, it is imperative to rigorously investigate the toxicological effects of MPs on freshwater ecosystems. This article provides a comprehensive analysis of the ecological toxicity effects of MP pollution, both in isolation and in combination with other pollutants, on freshwater aquatic organisms, including plankton, benthic organisms, and fish. The review elucidates potential mechanisms underlying these effects, which encompass oxidative stress, metabolic disorders, immune and inflammatory responses, dysbiosis of the gut microbiota, DNA damage, and cell apoptosis. This paper advocates for the integrated application of multi-omics technologies to investigate the molecular mechanisms underlying the toxicity of MPs to freshwater aquatic organisms from interdisciplinary and multifaceted perspectives. Additionally, it emphasizes the importance of enhancing research on the compounded pollution effects arising from various pollution modes, particularly in conjunction with other pollutants. This study aims to establish a foundation for assessing the ecological risks posed by MPs in freshwater ecosystem and offers valuable insights for the protection of aquatic biodiversity and ecosystem stability.

Intense and vibrant color construction and functionalization for protein macromolecule/polyamide two-component fabric by sustainable microbial nano prodigiosins based on adjustable pigment allocation

Silk/polyamide fabric inherits the advantages of natural and synthetic fibers, making them remarkable in textile and garment field. However, the use of synthetic chemicals for color construction and functionalization of silk/polyamide fabrics is problematic because of their non-renewable resources and harmful effects on the environment. Furthermore, achieving even color construction of silk and polyamide fibers in one bath is challenging due to their significant differences in chemical structure and surface properties. In this study, an environmentally friendly approach for color construction and functionalization of silk/polyamide fabric with microbial nano prodigiosins based on adjustable pigment allocation in one bath was proposed. Through investigating the mechanism of how the dye bath pH value influences the uptake amounts of pigments by two types of fibers, an almost equal proportion of pigment onto both fibers realized. In conclusion, the two-component fabric displayed the most vibrant and saturated color, excellent dyeing permeability, good UV protection and antibacterial performance. Moreover, the dyed fabric maintained smooth surface, high breaking strength and soil degradation ability. This study explored a potential way for the color construction and multi-functionalization of silk/polyamide fabrics to meet the growing demand for sustainable and value-added textiles.

Environmental efficacy of polyethylene microplastics: Enhancing the solidification of CuO nanoparticles and reducing the physiological toxicity to peanuts

Microplastics and metal-based nanoparticles (NPs) are environmental pollutants that have attracted significant attention. However, there have been relatively few studies on the combined pollution of these substances in the soil-plant system. To investigate the environmental impact and interaction mechanisms of these two pollutants, a pot experiment was conducted to examine the effects of soil exposure on peanut growth. The experiment results revealed that polyethylene (PE) had a minimal effect on peanut growth, while CuO NPs significantly inhibited peanut growth. Peanut biomass decreased by over 50 % in all Cu treatments. The presence of PE significantly impacted the dissolution and absorption of CuO NPs. When 0.5 % PE was present, the dissolution and transformation of CuO NPs were limited, resulting in a total Cu concentration of 458 mg/kg. Conversely, when 5 % PE was present, the dissolution and transformation of CuO NPs were promoted, leading to a DTPA-Cu concentration of 141 mg/kg, the highest level observed. The distribution of trace elements in peanut stems also responded to the differences in Cu concentration. Both pollutants significantly disrupted soil bacteria, with CuO NPs having a more pronounced effect than PE. Throughout the entire growth cycle of peanuts, no chemical adsorption occurred between PE and CuO NPs, and CuO NPs had no significant impact on the aging rate of PE. In summary, this study provides insights into the environmental impact and transport mechanisms of composite pollution involving microplastics and metal-based nanoparticles in the soil-peanut system.

Biodegradation: the best solution to the world problem of discarded polymers

The widespread use of polymers has made our lives increasingly convenient by offering a more convenient and dependable material. However, the challenge of efficiently decomposing these materials has resulted in a surge of polymer waste, posing environment and health risk. Currently, landfill and incineration treatment approaches have notable shortcomings, prompting a shift towards more eco-friendly and sustainable biodegradation approaches. Biodegradation primarily relies on microorganisms, with research focusing on both solitary bacterial strain and multi-strain communities for polymer biodegradation. Furthermore, directed evolution and rational design of enzyme have significantly contributed to the polymer biodegradation process. However, previous reviews often undervaluing the role of multi-strain communities. In this review, we assess the current state of these three significant fields of research, provide practical solutions to issues with polymer biodegradation, and outline potential future directions for the subject. Ultimately, biodegradation, whether facilitated by single bacteria, multi-strain communities, or engineered enzymes, now represents the most effective method for managing waste polymers.

Effects of salinity on naphthalene adsorption and toxicity of polyethylene microparticles on Artemia salina

Plastic pollution in aquatic ecosystems is increasing and plastic particles may adsorb and transport a diverse array of contaminants, thereby increasing their bioavailability to biota. This investigation aimed to evaluate the effects of varying polyethylene microplastics (PE MPs) and naphthalene (NAPH) concentrations on the survival and feeding rates of the model organism, Artemia salina, as well as NAPH adsorption to microplastics at different salinity levels (17, 75, 35.5 and 52.75 g L-1) under selected climate change scenarios. Survival (48 h) and feeding rates (6 h) of A. salina were also monitored, revealing that the presence of higher PE and NAPH concentrations lead to decreased survival rates while also increasing the number and size of microplastic particles in the saline solutions. Higher PE concentrations negatively affected A. salina feeding rates and NAPH concentrations were positively correlated with particle number and size, as well as with NAPH and PE adsorption rates in solution. Our findings demonstrate that the co-occurrence of microplastics and NAPH in aquatic environments can result in detrimental zooplankton survival and feeding rate effects. Furthermore, this interaction may contribute to the accumulation of these contaminants in the environment, highlighting the need to simultaneously monitor and mitigate the presence of microplastics and organic pollutants, like NAPH, in aquatic environments.

Bottlenecks in biobased approaches to plastic degradation

Plastic waste is an environmental challenge, but also presents a biotechnological opportunity as a unique carbon substrate. With modern biotechnological tools, it is possible to enable both recycling and upcycling. To realize a plastics bioeconomy, significant intrinsic barriers must be overcome using a combination of enzyme, strain, and process engineering. This article highlights advances, challenges, and opportunities for a variety of common plastics.

Exploring the hidden environmental pollution of microplastics derived from bioplastics: A review

Bioplastics might be an ecofriendly alternative to traditional plastics. However, recent studies have emphasized that even bioplastics can end up becoming micro- and nano-plastics due to their degradation under ambient environmental conditions. Hence, there is an urgent need to assess the hidden environmental pollution caused by bioplastics. However, little is known about the evolutionary trends of bibliographic data, degradation pathways, formation, and toxicity of micro- and nano-scaled bioplastics originating from biodegradable polymers such as polylactic acid, polyhydroxyalkanoates, and starch-based plastics. Therefore, the prime objective of the current review was to investigate evolutionary trends and the latest advancements in the field of micro-bioplastic pollution. Additionally, it aims to confront the limitations of existing research on microplastic pollution derived from the degradation of bioplastic wastes, and to understand what is needed in future research. The literature survey revealed that research focusing on micro- and nano-bioplastics has begun since 2012. This review identifies novel insights into microbioplastics formation through diverse degradation pathways, including photo-oxidation, ozone-induced degradation, mechanochemical degradation, biodegradation, thermal, and catalytic degradation. Critical research gaps are identified, including defining optimal environmental conditions for complete degradation of diverse bioplastics, exploring micro- and nano-bioplastics formation in natural environments, investigating the global occurrence and distribution of these particles in diverse ecosystems, assessing toxic substances released during bioplastics degradation, and bridging the disparity between laboratory studies and real-world applications. By identifying new trends and knowledge gaps, this study lays the groundwork for future investigations and sustainable solutions in the realm of sustainable management of bioplastic wastes.

Simulation Study of Polyethylene Terephthalate Hydrolase Adsorption on Self-Assembled Monolayers

Polyethylene terephthalate (PET) hydrolase, discovered in Ideonella sakaiensis (IsPETase), is a promising agent for the biodegradation of PET under mild reaction conditions, yet the thermal stability is poor. The efficient immobilization and orientation of IsPETase on different solid substrates are essential for its application. In this work, the combined parallel tempering Monte Carlo simulation with the all-atom molecular dynamics simulation approach was adopted to reveal the adsorption mechanism, orientation, and conformational changes of IsPETase adsorbed on charged self-assembled monolayers (SAMs), including COOH-SAM and NH2-SAM with different surface charge densities (SCDs). The results show that the protein adsorption orientation was determined not only by attraction interactions but also by repulsion interactions. IsPETase is adsorbed on the COOH-SAM surface with an "end-on" orientation, which favors the exposure of the catalyzed triplet to the solution. In addition, the entrance to the catalytic active center is larger on the COOH-SAM surface with a low SCD. This work reveals the controlled orientation and conformational information on IsPETase on charged surfaces at the atomistic level. This study would certainly promote our understanding of the mechanism of IsPETase adsorption and provide theoretical support for the design of substrates for IsPETase immobilization.

Berry wax improves the physico-mechanical, thermal, water barrier properties and biodegradable potential of chitosan food packaging film

Chitosan (CT) is extensively applied in developing food packaging films due to its non-toxic, biodegradable, and good film-forming properties. But CT-based single polymer film has issues with poor physico-mechanical, thermal, and light barrier properties. Therefore, this study aimed to incorporate natural berry wax (BYW) at various concentrations (5 %, 10 %, 15 %, 20 %, and 25 %, wt%) into CT to improve the quality characteristics of CT film. The microstructure of the film matrix was effectively proven to be compatible with BYW through the utilization of SEM, XRD, and FTIR spectroscopy. The results demonstrated that the quality parameters of CT/BYW composite film were significantly affected by the increasing concentration of BYW. The integration of BYW with a concentration of 5 % to 20 % to CT substantially improved the film characteristics by reducing moisture content, swelling power, solubility, and water vapor permeability, increasing the film's opacity, thermal stability, and tensile strength as well as enhancing the biodegradable potential. Furthermore, CT/BYW films showed higher thermal stability and UV and visible light resistance compared to pure CT film. Taken together, the CT film with 20 % berry wax showed the best film characteristics and biodegradable potential, which could be promising for enhancing the shelf-life of various food products.

Additive manufacturing of sustainable biomaterials for biomedical applications

Biopolymers are promising environmentally benign materials applicable in multifarious applications. They are especially favorable in implantable biomedical devices thanks to their excellent unique properties, including bioactivity, renewability, bioresorbability, biocompatibility, biodegradability and hydrophilicity. Additive manufacturing (AM) is a flexible and intricate manufacturing technology, which is widely used to fabricate biopolymer-based customized products and structures for advanced healthcare systems. Three-dimensional (3D) printing of these sustainable materials is applied in functional clinical settings including wound dressing, drug delivery systems, medical implants and tissue engineering. The present review highlights recent advancements in different types of biopolymers, such as proteins and polysaccharides, which are employed to develop different biomedical products by using extrusion, vat polymerization, laser and inkjet 3D printing techniques in addition to normal bioprinting and four-dimensional (4D) bioprinting techniques. This review also incorporates the influence of nanoparticles on the biological and mechanical performances of 3D-printed tissue scaffolds. This work also addresses current challenges as well as future developments of environmentally friendly polymeric materials manufactured through the AM techniques. Ideally, there is a need for more focused research on the adequate blending of these biodegradable biopolymers for achieving useful results in targeted biomedical areas. We envision that biopolymer-based 3D-printed composites have the potential to revolutionize the biomedical sector in the near future.

Study on the biodegradation of polybutylene adipate-co-terephthalate/starch film containing deep eutectic solvent

Poly (butylene adipate-co-terephthalate) (PBAT) has attracted much attention as a biodegradable polymer, but its biodegradation speed is slow. Starch was blended with PBAT to develop daily packing film with high biodegradation speed, and deep eutectic solvent (DES) composed of choline chloride (CHCl)/glycerol (Gly) (molar ratio of 1:2) was used as a novel plasticizer. The hydrophilic starch is in favor of the breeding of microorganisms, at the same time DES can provide energy for the breeding. The degradation was traced in a simulated composting test using kitchen waste. After the PBAT/starch-DES film was buried in a mixture of food residue for 90 D, the relative weight molecular weight (M_w) of the PBAT decreased by about 50%. Furthermore, with the help of DES, the compatibility between PBAT and starch was improved, the PBAT/starch-DES film became more transparent than the PBAT and PBAT/starch film, and its tensile strength reached 7.9 MPa with an elongation at break of 335.6%. This work provided a simple and efficient solution to obtain rapidly degradable films.

Microbial degradation of low-density polyethylene by Neopestalotiopsis phangngaensis

Low-density polyethylene (LDPE) has been commercially used and accumulated as plastic solid waste. LDPE has also been found to be a non-degradable waste for decades and found as a pollution source in the environment. In this study, 65 fungi were screened for their biodegradation of LDPE. The fungi Neopestalotiopsis phangngaensis, Alternaria burnsii, Alternaria pseudoeichhorniae, and Arthrinium sacchari showed significant potential in LDPE biodegradation. These fungi were individually cultured with an LDPE sheet as a carbon source for 90 days. A maximum weight loss of the LDPE sheet was detected by the fungus N. phangngaensis (54.34%). This fungus also revealed the highest reduction rate of tensile strength of the LDPE sheet (0.33 MPa). The morphological surface of LDPE culturing with N. phangngaensis was crack, pit, and rough analyzed by scanning electron microscopy. The biodegradation of the LDPE sheet by N. phangngaensis was also confirmed by the Sturm test and analysis of enzymatic activities. The Sturm test showed the highest decomposition of the LDPE sheet by N. phangngaensis into CO₂ with 2.14 g/L after incubation. Enzymatic activities of laccase, manganese peroxidase, and lignin peroxidase enzymes were found by N. phangngaensis during the LDPE degradation. The volatile organic compounds in culture supernatant of N. phangngaensis were also investigated. The major compounds were 3Z-diethyl acetal hexenal, 2E,4E-decadienol, and 2Z-diethyl acetal hexenal. This study reveals the utilization of the fungus N. phangngaensis as the carbon source at a considerable biodegradation rate without any prior treatment. Therefore, the fungus N. phangngaensis may be applied as an alternative degrader for LDPE degradation in the environment.

The Use of Mycelial Fungi to Test the Fungal Resistance of Polymeric Materials

There are two main themes in the research on the biodegradation of industrial materials by mycelial fungi. The challenge of reducing environmental pollution necessitates the creation of biodegradable polymers that allow microorganisms, including mycelial fungi, to degrade them to low-molecule soluble substances. Additionally, to minimize the biodegradation of industrial materials while they are operating in the environment, there is a need to produce fungi-resistant polymer compositions. The fungal resistance of industrial materials and products can be assessed using a specific set of mycelial fungi cultures. Test cultures selected for this purpose are supported in the All-Russian Collection of Microorganisms (VKM). This review addresses the principle of culture selection to assess the fungal resistance of industrial materials and evaluates the results of the tests using these cultures.

Leads and hurdles to sustainable microbial bioplastic production

Indiscriminate usage, disposal and recalcitrance of petroleum-based plastics have led to its accumulation leaving a negative impact on the environment. Bioplastics, particularly microbial bioplastics serve as an ecologically sustainable solution to nullify the negative impacts of plastics. Microbial production of biopolymers like Polyhydroxyalkanoates, Polyhydroxybutyrates and Polylactic acid using renewable feedstocks as well as industrial wastes have gained momentum in the recent years. The current study outlays types of bioplastics, their microbial sources and applications in various fields. Scientific evidence on bioplastics has suggested a unique range of applications such as industrial, agricultural and medical applications. Though diverse microorganisms such as Alcaligenes latus, Burkholderia sacchari, Micrococcus species, Lactobacillus pentosus, Bacillus sp., Pseudomonas sp., Klebsiella sp., Rhizobium sp., Enterobacter sp., Escherichia sp., Azototobacter sp., Protomonas sp., Cupriavidus sp., Halomonas sp., Saccharomyces sp., Kluyveromyces sp., and Ralstonia sp. are known to produce bioplastics, the industrial production of bioplastics is still challenging. Thus this paper also provides deep insights on the advancements made to maximise production of bioplastics using different approaches such as metabolic engineering, rDNA technologies and multitude of cultivation strategies. Finally, the constraints to microbial bioplastic production and the future directions of research are briefed. Hence the present review emphasizes on the importance of using bioplastics as a sustainable alternative to petroleum based plastic products to diminish environmental pollution.

Research and Application of Polypropylene Carbonate Composite Materials: A Review

The greenhouse effect and plastic pollution caused by the accumulation of plastics have led to a global concern for environmental protection, as well as the development and application of biodegradable materials. Polypropylene carbonate (PPC) is a biodegradable polymer with the function of "carbon sequestration", which has the potential to mitigate the greenhouse effect and the plastic crisis. It has the advantages of good ductility, oxygen barrier and biocompatibility. However, the mechanical and thermal properties of PPC are poor, especially the low thermal degradation temperature, which limits its industrial use. In order to overcome this problem, PPC can be modified using environmentally friendly materials, which can also reduce the cost of PPC-based products to a certain extent and enhance their competitiveness in terms of improving their mechanical and thermal properties. In this paper, we present different perspectives on the synthesis, properties, degradation, modification and post-modification applications of PPC. The modification part mainly introduces the influence of inorganic materials, natural polymer materials and degradable polymers on the performance of PPC. It is hoped that this work will serve as a reference for the early promotion of PPC.