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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. [Display omitted] • This review focuses on emerging trends in micro(nano)bioplastic research. • This study found that hidden pollution from bioplastics is an emerging problem. • This work serves as a strong platform for future micro(nano)bioplastic research. • Defining factors for completed degradation of bioplastics is a key research gap. [ABSTRACT FROM AUTHOR]

Plastic pollution has become a major global concern, posing numerous challenges for the environment and wildlife. Most conventional ways of plastics degradation are inefficient and cause great damage to ecosystems. The development of biodegradable plastics offers a promising solution for waste management. These plastics are designed to break down under various conditions, opening up new possibilities to mitigate the negative impact of traditional plastics. Microbes, including bacteria and fungi, play a crucial role in the degradation of bioplastics by producing and secreting extracellular enzymes, such as cutinase, lipases, and proteases. However, these microbial enzymes are sensitive to extreme environmental conditions, such as temperature and acidity, affecting their functions and stability. To address these challenges, scientists have employed protein engineering and immobilization techniques to enhance enzyme stability and predict protein structures. Strategies such as improving enzyme and substrate interaction, increasing enzyme thermostability, reinforcing the bonding between the active site of the enzyme and substrate, and refining enzyme activity are being utilized to boost enzyme immobilization and functionality. Recently, bioengineering through gene cloning and expression in potential microorganisms, has revolutionized the biodegradation of bioplastics. This review aimed to discuss the most recent protein engineering strategies for modifying bioplastic-degrading enzymes in terms of stability and functionality, including enzyme thermostability enhancement, reinforcing the substrate binding to the enzyme active site, refining with other enzymes, and improvement of enzyme surface and substrate action. Additionally, discovered bioplastic-degrading exoenzymes by metagenomics techniques were emphasized. [Display omitted] • Conventional recycling methods could be replaced by biological ones that offer an ecosystem-friendly approach. • The aerobic and anaerobic mechanisms of microbial degradation for bioplastic have been reviewed. • The stability and activity of extracellular microbial enzymes can be influenced by environmental factors. • The preparation of bioplastic-degrading enzymes in various microorganisms using metagenomics techniques has been discussed. • Protein engineering techniques of bioplastic-degrading enzymes have been emphasized to improve biocatalytic performance. [ABSTRACT FROM AUTHOR]

Plastics have a significant role in various sectors of the global economy since they are widely utilized in agriculture, architecture, and construction, as well as health and consumer goods. They play a crucial role in several industries as they are utilized in the production of diverse things such as defense materials, sanitary wares, tiles, plastic bottles, artificial leather, and various other household goods. Plastics are utilized in the packaging of food items, medications, detergents, and cosmetics. The overconsumption of plastics presents a significant peril to both the ecosystem and human existence on Earth. The accumulation of plastics on land and in the sea has sparked interest in finding ways to breakdown these polymers. It is necessary to employ suitable biodegradable techniques to decrease the accumulation of plastics in the environment. To address the environmental issues related to plastics, it is crucial to have a comprehensive understanding of the interaction between microorganisms and polymers. A wide range of creatures, particularly microbes, have developed techniques to survive and break down plastics. This review specifically examines the categorization of plastics based on their thermal and biodegradable properties, as well as the many types of degradation and biodegradation. It also discusses the various types of degradable plastics, the characterization of biodegradation, and the factors that influence the process of biodegradation. The plastic breakdown and bioremediation capabilities of these microbes make them ideal for green chemistry applications aimed at removing hazardous polymers from the ecosystem. [Display omitted] • Recent advances in the microbial and enzymatic degradation of synthetic plastics. • Individual and combinatorial degradation of petro-plastics for low-carbon economy. • Employment of isolated and mutant enzymes to enhance the efficiency of biodegradation. • Existing approaches & assays for degradation assessment based on varying properties. • Potent hazards of fragmented plastic, micro- and nanoplastics to the living beings. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are plastic particles in a size ranging from 1 mm to 5 mm in diameter, and are formed by the breakdown of plastics from different sources. They are emerging environmental pollutants, and pose a great threat to living organisms. Improper disposal, inadequate recycling, and excessive use of plastic led to the accumulation of MP in the environment. The degradation of MP can be done either biotically or abiotically. In view of that, this article discusses the molecular mechanisms that involve bacteria, fungi, and enzymes to degrade the MP polymers as the primary objective. As per as abiotic degradation is concerned, two different modes of MP degradation were discussed in order to justify the effectiveness of biotic degradation. Finally, this review is concluded with the challenges and future perspectives of MP biodegradation based on the existing research gaps. The main objective of this article is to provide the readers with clear insight, and ideas about the recent advancements in MP biodegradation. [Display omitted] • The accumulation of MPs in the environment is summarized. • The effects of MPs on marine, human health and animals are reviewed. • The mechanism and the advancements in biodegradation of microplastics are discussed. • The challenges and future perspectives of biodegradation of MPs are emphasized. [ABSTRACT FROM AUTHOR]

Superworm (larve of Zophobas atratus) could consume foams of expanded polystyrene plastics. However, there is no sufficient understanding of the impact of microplastics on superworms and the degradation pathways of polystyrene. Herein, we explored the weight and survival change of superworms while fed with polystyrene microplastics, and found that survival rate and mean weight would reduce. In terms of gut microbial community structure of surperworms, significant shifts were detected with the relative abundance of Hafnia-Obesumbacterium sp. increasing. In addition, we domesticated two microbiota from the gut of superworms, and confirmed their ability to degrade PS in vitro. The last but most important, 1291 metabolites were identified by HPLC-TOF-MS/MS, and six metabolites related to polystyrene degradation were identified through comparative metabolomic analysis. According to the content and pathways of these metabolites, three metabolic pathways of polystyrene were (a) styrene-phenylacetyl-CoA-L-2-aminoadipic acid; (b) styrene-phenylacetyl-CoA-benzaldehyde; (c) styrene-2-hydroxyacetophenone. These results would help to further screen bacteria of PS degradation and investigate PS metabolic pathways in invertebrates. [Display omitted] • PS microplastics negatively affected the survival rate of surperworms. • Two microbiotas degrading PS were selected from gut microbiome. • Three metabolic pathways of PS degradation in superworms were proposed. [ABSTRACT FROM AUTHOR]

Microparticles made from naturally occurring materials or biodegradable plastics such as poly(3-hydroxy butyrate)-co-(3-hydroxy valerate), PHBV, are being evaluated as alternatives to microplastics in personal care product applications but limited data is available on their ultimate biodegradability (mineralization) in down the drain environmental compartments. An OECD 301B Ready Biodegradation Test was used to quantify ultimate biodegradability of microparticles made of PHBV foam, jojoba wax, beeswax, rice bran wax, stearyl stearate, blueberry seeds and walnut shells. PHBV polymer was ready biodegradable reaching 65.4 ± 4.1% evolved CO 2 in 5 d and 90.5 ± 3.1% evolved CO 2 in 80 d. PHBV foam microparticles (125–500 μm) were mineralized extensively with >66% CO 2 evolution in 28 d and >82% CO 2 evolution in 80 d. PHBV foam microparticles were mineralized at a similar rate and extent as microparticles made of jojoba wax, beeswax, rice bran wax, and stearyl stearate which reached 84.8 ± 4.8, 84.9 ± 2.2, 82.7 ± 4.7, and 86.4 ± 3.2% CO 2 evolution respectively in 80 d. Blueberry seeds and walnut shells mineralized more slowly only reaching 39.3 ± 6.9 and 5.1 ± 2.8% CO 2 evolution in 80 d respectively. [ABSTRACT FROM AUTHOR]

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. aminophilus B1 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 CO 2 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 (CO 2 evolution of 8.86 g.l-l and percentage weight loss of 18.21 %) with increased electrical conductivity, followed by B. subtilis V8 (CO 2 evolution of 8.10 g.l-l and percentage weight loss of 16.12 %), A. calcoaceticus V4 (CO 2 evolution of 7.21 g.l-l and percentage weight loss of 15.44 %), P. putida C 2-5 (CO 2 evolution of 5.76 g.l-l and percentage weight loss of 13.30 %), and P. aminophilus B1 4- (CO 2 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. [Display omitted] • Biodegradation is an eco-friendly approach for microplastic waste management. • Polyphasic approach (CO 2 estimation, weight loss, SEM, fourier transform FT-IR, and electrical conductivities analysis) the reproducibility of plastic biodegradation. • Electrical conductivity has developed on degraded plastic. • Investigation helpful for developing waste management technology. [ABSTRACT FROM AUTHOR]

Discarded polyethylene (PE) mulch film has led to persistent agricultural pollution. Biodegradation of plastic waste is considered as a promising solution that can potentially overcome environmental and economic problems. In this study, a novel bacterium (Bacillus paramycoides) was isolated from a waste mulch recycling plant and showed an extraordinary ability to customize polyethylene film. It was observed by scanning electron microscopy that a large number of pits and wrinkle cracks existed on the polyethylene, indicating that the strain used PE film as the sole carbon source. Meanwhile, the loss of weight of the film was tested continuously, and approximately 12% of the initial weight of the film was found to be lost within 45 days after coincubation with TW-2. The surface hydrophobicity of the polyethylene film decreased while the surface tension increased from 9.755 to 31.013. Fourier transform infrared (FTIR) analysis indicated that absorption peaks near 1740 cm−1 and 2760 cm−1 were attributed to the stretching vibrations of aldehyde and carboxyl groups, respectively, suggesting that hydrophilic groups were produced. This was also confirmed by XPS spectroscopy analysis. X-ray diffraction (XRD) analysis also showed that the relative crystallinity decreased from 33% to 11.51%. In addition, GPC analysis showed that the molecular weight decreased, while the proportion of low molecular weight fragments increased. These results strongly indicated that the PE film was able to be degraded to some extent by the strain. Finally, a new biodegradable mechanism for polyethylene was proposed. [Display omitted] • One Bacillus paramycoides was isolated and capable of efficiently degrading PE mulch. • Biodegradation of PE mulch was confirmed by FTIR, SEM, XRD, GPC, DSC,WCA and XPS. • The degradation mechanism of biodegradable polyethylene is discussed. [ABSTRACT FROM AUTHOR]

Microbial consortia-mediated biodegradation of 1,4-dioxane (1,4-D), an emerging water contaminant, is always a superior choice over axenic cultures. Thus, better understanding of the functions of coexisting microbes and their interspecies interactions within the consortia is crucial for predicting biodegradation efficiency and designing efficient 1,4-D-degrading microbial consortia. This study evaluated how microbial community compositions and interspecies interactions govern the microbial consortia-mediated 1,4-D biodegradation by investigating the biodegradability and microbial community dynamics of both enriched (N112) and synthetic (SCDs and SCDNs) microbial consortia in the absence or presence of additional organic compound (AOC). In the absence of AOC, N112 exhibited 100% 1,4-D biodegradation efficiency at a rate of 12.5 mg/L/d, whereas the co-occurrence of AOC resulted in substrate-dependent biodegradation inhibition and thereby reduced the biodegradation efficiency and activity (2.0–10.0 mg/L/d). The coexistence and negative influence of certain low-abundant non-degraders on both 1,4-D-degraders and key non-degraders in N112 was identified as the prime cause behind such biodegradation inhibition. Comparing with N112, SCDN-1 composed of 1,4-D-degraders and key non-degraders significantly improved the 1,4-D biodegradation efficiency in the presence of AOC, confirming the absence of negative influence of low-abundant non-degraders and cooperative interactions between 1,4-D-degraders and key non-degraders in SCDN-1. On the contrary, both two-species and three-species SCDs comprised of only 1,4-D-degraders resulted in lower 1,4-D biodegradation efficiency as compared to SCDN-1 under all treatment conditions, while max. 91% 1,4-D biodegradation occurred by SCDs in the absence of AOC. These results were attributed to the negative interaction among 1,4-D-degraders and the absence of complementary roles of key non-degraders in SCDs. The findings improve our understanding of how interspecies interactions can regulate the intrinsic abilities and functions of coexisting microbes during biodegradation in complex environments and provide valuable guidelines for designing highly efficient and robust microbial consortia for practical bioremediation of 1,4-D like emerging organic contaminants. [Display omitted] • 1,4-dioxane degradation efficiency of enriched and synthetic consortia were studied. • Additional substrate-dependent biodegradation efficiency was observed. • Biodegradation efficacy was governed by interspecies interactions within consortium. • A synthetic consortium having superior biodegradation efficiency was constructed. • Not all but key non-degraders were the prime contributors for efficient biodegradation. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is one of the mass-produced recalcitrant plastics with a high environmental resistance but extremely low biodegradability. Therefore, improperly disposed PU waste adds significantly to plastic pollution, which must be addressed immediately. In recent years, there has been an increasing number of reports on plastic biodegradation in insect larvae, especially those that can feed on polyethylene and polystyrene. This study revealed that yellow mealworm (Tenebrio molitor) larvae can chew and ingest polyether-PU foams efficiently, resulting in a significant mass loss of nearly 67% after 35 days at a similar survival rate compared to when fed on bran. However, polyether-PU fragments were found in the frass of T. molitor , indicating that polyether-PU biodegradation and bioconversion in intestinal tracts were not complete. The scission of ether and urethane bonds in the polyether-PU can be evidenced by comparing polymer fragments recovered from frass with the pristine ones using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Gel permeation chromatography suggested the release of low-molecular-weight oligomers as a result of the biodegradation, which also resulted in poor thermal stability of the polyether-PU foam as determined by thermogravimetric analysis. High-throughput sequencing of the gut microbiome revealed significant changes in the microbial community populations due to the polyether-PU diet, for example, an increase in the families Enterobacteriaceae and Streptococcaceae, suggesting that these microorganisms may contribute to the polyether-PU biodegradation. [Display omitted] • Yellow mealworms can grow on a diet of polyether-PU foam alone. • FTIR, XPS, TGA revealed the cleavage of chemical bonds and the changes in thermal stability of polyether-PU foam found in feces. • GPC confirmed a decreased molecular weight of polyether-PU foam found in feces as a result of depolymerization. • The gut microbial community of yellow mealworms varied significantly in association with the polyether-PU diet. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are increasingly of interest for environmentally open applications. Therefore, completely mineralising ILs are highly desirable. We reviewed the current state of knowledge on ILs' environmental biodegradability and identified research needs. Literature data were evaluated as for applied standard methods (e.g. OECD, ISO, APHA) for biodegradation of ILs in order to get an overview on the validity of the test results received and ILs' biodegradability. 109 studies were evaluated. The ILs were categorised based on the cation's core structure. The biodegradation data was classified according to a traffic light system (red: 0–19% degradation, amber: 20–59% degradation, green: ≥ 60% degradation). Not all studies could be assessed for compliance with the test guidelines due to missing test parameters. Moreover, no study discussed all validation criteria as defined by the test guidelines. Consequently, the reliability and quality of the existing biodegradation data is restrained. With regard to the different cations classified for ≥ 60% biodegradability, phosphonium ILs are the least biodegradable, followed by imidazolium ones. The most ILs that were biodegradable are cholinium ILs. The results indicate the need for more and qualitatively better testing according to standard methods including application and reporting of all validation criteria in order to get reliable data that enables the comparison of the test data and a comprehensive understanding of ILs' biodegradability. Moreover, reliable data allows the selection of sufficiently environmentally biodegradable ILs if an introduction into the environment during use cannot be excluded. [Display omitted] • Review delivered 109 ILs biodegradation studies that applied standardised methods. • Methods were evaluated on compliance with the guidelines, validity of the data. • Biodegradation data on 716 different ILs including 29 ILs mixtures were provided. • 34 ILs classified as readily biodegradable in accordance with the guidelines. • More valid ILs biodegradation data based on standard methods needed. [ABSTRACT FROM AUTHOR]

To date, the introduction of biodegradable plastics such as PLA in anaerobic digestion systems has been limited by a very low rate of biodegradation. To overcome these limitations, pretreatment technologies can be applied. In this study, the impact of pretreatments (mechanical, thermal, thermo-acid, and thermo-alkaline) was investigated. Mechanical pretreatment of PLA improved its biodegradation rate but did not affect the ultimate methane potential (430–461 NL CH 4 kg−1 VS). In parallel, thermal and thermo-acid pretreatments exhibited a similar trend for PLA solubilization. Both of these pretreatments only achieved substantial solubilization (>60%) at higher temperatures (120 and 150 °C). At lower temperatures (70 and 90 °C), negligible solubilization (between 1 and 6%) occurred after 48 h. By contrast, coupling of thermal and alkaline pretreatment significantly increased solubilization at the lower temperatures (70 and 90 °C). In terms of biodegradation, thermo-alkaline pretreatment (with 5% w/v Ca(OH) 2) of PLA resulted in a similar methane potential (from 325 to 390 NL CH 4 kg−1 VS) for 1 h at 150 °C, 6 h at 120 °C, 24 h at 90 °C, and 48 h at 70 °C. Reduction of the Ca(OH) 2 concentration (from 5% to 0.5% w/v) highlighted that a concentration of 2.5% w/v was sufficient to achieve a substantial level of biodegradation. Pretreatment at 70 and 90 °C using 2.5% w/v Ca(OH) 2 for 48 h resulted in biodegradation yields of 73% and 68%, respectively. Finally, a good correlation (R2 = 0.90) was found between the PLA solubilization and its biodegradation. [Display omitted] • PLA has very low biodegradation rate under mesophilic anaerobic digestion. • Mechanical pretreatment only slightly improved the biodegradation kinetic of PLA. • Thermal pretreatment (120 or 150 °C) resulted in substantial improvement of biodegradation. • Addition of Ca(OH) 2 allowed to find similar biodegradation at lower temperature. • 70 °C with 2.5% w/v Ca(OH) 2 for 48 h allows 73% biodegradation of PLA in 30 days. [ABSTRACT FROM AUTHOR]

Increasing world population and industrial activities have enhanced anthropogenic pollution, plastic pollution being especially alarming. So, plastics should be recycled and/or make them biodegradable. Chemical and physical remediating methods are usually energy consuming and costly. In addition, they are not ecofriendly and usually produce toxic byproducts. Bioremediation is a proper option as it is cost-efficient and environmentally friendly. Plastic production and consumption are increasing daily, and, as a consequence, more microorganisms are exposed to these nonbiodegradable polymers. Therefore, investigating new efficient microorganisms and increasing the knowledge about their biology can pave the way for efficient and feasible plastic bioremediation processes. In this sense, omics, systems biology and bioinformatics are three important fields to analyze the biodegradation pathways in microorganisms. Based on the above-mentioned technologies, researchers can engineer microorganisms with specific desired properties to make bioremediation more efficient. [Display omitted] • Plastic pollution is one the most challenging environmental problems worldwide. • The plastic degrading ability of microorganisms is reviewed. • Recent achievements in microbial degradation of polymers are reviewed. • Omics approaches and bioinformatics are considered. [ABSTRACT FROM AUTHOR]

Developing novel renewable (and preferably biodegradable) materials has become recurrent due to the growing concerns with environmental impacts of high volumes of plastic waste produced from oil-based sources over the past decades. This study aimed at developing bioplastics from a mixture of starch and xylan in variable ratios, and the combined effect of α-cellulose and holocellulose extracted from sugarcane bagasse added to the process. The disintegration of bioplastics was evaluated in both soil and composting. The ecotoxicity analyses with Saccharomyces cerevisiae , Bacillus subtilis and seeds of Cucumis sativus were conducted after disintegration. All formulations based on 5% (w/v) of total polysaccharides were dried at 30 °C and resulted in homogeneous and non-brittle bioplastics. The composting results showed that all bioplastic formulations disintegrated in 3 days, whereas the 25/75% (xylan/starch, w/w) formulation vanished in soil within 13 days. The ecotoxicity data showed no inhibition of microbial growth after biodegradation, yielding 100% of seed germination. Despite the positive influence of the bioplastic degradation on the root and hypocotyl growth, temporary inhibition of C. sativus tissues exposed to soil washing (10 days of disintegration) was observed. The study demonstrated that xylan/starch bioplastics result in non-ecotoxic biodegradable materials. [Display omitted] • Bioplastic was developed with xylan/starch combining α-cellulose and holocellulose. • Xylan/starch-based bioplastic disintegrated in 13 days after burial in the soil. • Total time for the disintegration of bioplastic in compost was reduced in relation to burial in soil. • Seed germination was not harmed by the disintegration of the bioplastic. • Temporary phytotoxicity was detected after 10 days of disintegration. [ABSTRACT FROM AUTHOR]

Plastics use is growing due to its applications in the economy, human health and aesthetics. The major plastic particles in the form of microplastics (MPs) released into the environment are made up of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), and polyethylene terephthalate (PET). Tremendous usage and continuous accumulation of MPs in the environment pose a global threat to ecosystems and human health. The current knowledge of biotechnological, aerobic and aerobic biodegradation approaches emphasizes the microbial culture's potential towards MPs removal. This review selectively provides recent biotechnological advances such as biostimulation, bioaugmentation and enzymatic biodegradation that can be applied for MPs removal by biodegradation and bioaccumulation. This review summarizes the knowledge and the research exploration on the biodegradation of synthetic organic MPs with different biodegradability. However, further research is still needed to understand the underlying mechanism of MPs biodegradation in soil and water systems, leading to the development of an effective method for MPs removal. [Display omitted] • Identifying the type of MPs helps to find an effective biodegradation method. • Biological degradation of MPs can take place in an aerobic or anaerobic environment. • The bioremediation of MPs is at the embryonic stage and laboratory scale. • Biotechnological advances for biodegradation can solve the MPs pollution. [ABSTRACT FROM AUTHOR]