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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]

The environmental impact of biodegradable polylactic acid microplastics (PLA-MPs) has become a global concern, with documented effects on soil health, nutrient cycling, water retention, and crop growth. This study aimed to assess the repercussions of varying concentrations of PLA-MPs on rice, encompassing aspects such as growth, physiology, and biochemistry. Additionally, the investigation delved into the influence of PLA-MPs on soil bacterial composition and soil enzyme activities. The results illustrated that the highest levels of PLA-MPs (2.5%) impaired the photosynthesis activity of rice plants and hampered plant growth. Plants exposed to the highest concentration of PLA-MPs (2.5%) displayed a significant reduction of 51.3% and 47.7% in their root and shoot dry weights, as well as a reduction of 53% and 49% in chlorophyll a and b contents, respectively. The activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) in rice leaves increased by 3.1, 2.8, 3.5, and 5.2 folds, respectively, with the highest level of PLA-MPs (2.5%). Soil enzyme activities, such as CAT, urease, and dehydrogenase (DHA) increased by 19.2%, 10.4%, and 22.5%, respectively, in response to the highest level of PLA-MPs (2.5%) application. In addition, PLA-MPs (2.5%) resulted in a remarkable increase in the relative abundance of soil Proteobacteria , Nitrospirae , and Firmicutes by 60%, 31%, and 98.2%, respectively. These findings highlight the potential adverse effects of PLA-MPs on crops and soils. This study provides valuable insights into soil-rice interactions, environmental risks, and biodegradable plastic regulation, underscoring the need for further research. [Display omitted] • Polylactic acid microplastics (PLA-MPs) induced oxidative stress in rice plants. • PLA-MPs adversely affected the growth of rice plants. • Rice photosynthetic activity was reduced by PLA-MPs. • PLA-MPs increased the activities of soil enzymes. • Rice-rhizosphere bacterial communities were altered by PLA-MPs. [ABSTRACT FROM AUTHOR]

The increasing prevalence of microplastics in the environment has become a concern for various ecosystems, including wetland ecosystems. Here, we investigated the effects of three popular microplastic types: polyethylene, polylactic acid, and tire particles at 5 °C and 25 °C on the sediment microbiome and metabolome at the 3% (w/w) level. Results indicated that temperature greatly influenced catalase and neutral phosphatase activities, whereas the type of microplastic had a more significant impact on urease and dehydrogenase activities. The addition of microplastic, especially tire particles, increased microbial diversity and significantly altered the microbial community structure and metabolic profile, leading to the formation of different clusters of microbial communities depending on the temperature. Nonetheless, the effect of temperature on the metabolite composition was less significant. Functional prediction showed that the abundance of functional genes related to metabolism and biogeochemical cycling increased with increasing temperature, especially the tire particles treatment group affected the nitrogen cycling by inhibiting ureolysis and nitrogen fixation. These observations emphasize the need to consider microplastic type and ambient temperature to fully understand the ecological impact of microplastics on microbial ecosystems. [Display omitted] • Evaluated the effects of polyethylene, polylactic acid, and tire particles (microplastics - MPs) on sediment. • MPs, especially tire particles, increased microbial diversity at higher temperatures. • Temperature influenced microbial diversity dynamics and had less of an effect on metabolites. • Comparatively, tire particle treatments had unique microbial communities and different metabolites. [ABSTRACT FROM AUTHOR]

Aged microplastics are ubiquitous in the aquatic environment, which inevitably accumulate metals, and then alter their migration. Whereas, the synergistic behavior and effect of microplastics and Hg(II) were rarely reported. In this context, the adsorptive behavior of Hg(II) by pristine/aged microplastics involving polystyrene, polyethylene, polylactic acid, and tire microplastics were investigated via kinetic (pseudo-first and second-order dynamics, the internal diffusion model), Langmuir, and Freundlich isothermal models; the adsorption and desorption behavior was also explored under different conditions. Microplastics aged by ozone exhibited a rougher surface attached with abundant oxygen-containing groups to enhance hydrophilicity and negative surface charge, those promoted adsorption capacity of 4–20 times increment compared with the pristine microplastics. The process (except for aged tire microplastics) was dominated by a monolayer chemical reaction, which was significantly impacted by pH, salinity, fulvic acid, and co-existing ions. Furthermore, the adsorbed Hg(II) could be effectively eluted in 0.04% HCl, simulated gastric liquids, and seawater with a maximum desorption amount of 23.26 mg/g. An artificial neural network model was used to predict the performance of microplastics in complex media and accurately capture the main influencing factors and their contributions. This finding revealed that aged microplastics had the affinity to trap Hg(II) from freshwater, whereafter it released the Hg(II) once transported into the acidic medium, the organism's gastrointestinal system, or the estuary area. These indicated that aged microplastics could be the sink or the source of Hg(II) depending on the surrounding environment, meaning that aged microplastics could be the vital carrier to Hg(II). [Display omitted] • The MPs exhibited abundant multipoles and active groups after ozone aging. • The adsorption and desorption mechanisms of Hg(II) were elaborated in depth. • BP-ANN model was adopted to predict the adsorptive properties of MPs. • The aged MPs played a vital carrier role in the transportation of Hg(II). [ABSTRACT FROM AUTHOR]

Agricultural mulch films are frequently applied to achieve high yield, resulting in large quantities of microplastic (MP) pollution in agroecosystem. However, studies focusing specifically on the diversity of MP-degrading enzymes and related microbial communities have yet to be conducted. Here, we established a soil microcosmic incubation with addition of 5% (w/w) conventional (low-density polyethylene (LDPE)) and biodegradable (blend of polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT)) MPs for incubation 90 days. The DNA samples extracted from soils and plastisphere of MPs were examined by metagenomics and genome binning methods, specifically targeting carbohydrate-active enzymes (CAZymes) and plastic-degrading enzymes (PDZymes). The results revealed that plastisphere of MPs exhibited significantly distinct patterns of CAZymes and PDZymes from soils, and abundances of all examined exoenzymes were higher in plastisphere than those in soils. Plastisphere of LDPE-MPs selectively enriched proteases and alkane monooxygenase (alkB), and required families of carbohydrate-binding module (CBM) to increase the binding of CAZymes with MPs. Dissimilarly, diverse CAZymes with high abundances were observed in the plastisphere of PBAT-PLA MPs and esterases were important indicative PDZymes for PBAT-PLA degradation. The enriched exoenzymes in plastisphere of LDPE-MPs were mainly assigned to Actinobacteria while Proteobacteria with higher abundance in plastisphere of PBAT-PLA MPs containing most indicative exoenzymes. Moreover, a high-quality genome classified as Amycolatopsis japonica was reconstructed and found to contain one or more gene copies of indicative exoenzymes for polyethylene. Two novel genomes classified as Sphingomonas were selectively enriched in plastisphere of PBAT-PLA MPs and contained diverse genes encoding degrading exoenzymes. Taken together, our study highlighted the CAZymes and PDZymes can be exploited as potent microbial strategies for solving MPs pollution in croplands. [Display omitted] • MPs enriched a wide range of CAZymes and PDZymes compared to soils. • PE required CBM to enhance enzyme hydrolysis and selected proteases and alkane monooxygenase. • Diverse CAZymes and esterases as the important indicator act on BD biodegradation. • The potential PE degraders assigned to Actinobacteria while members of Proteobacteria enriched in BD. • Amycolatopsis japonica and Sphingononas were identified as the potential degraders for PE and BD, respectively. [ABSTRACT FROM AUTHOR]

Agricultural mulch films are frequently applied to achieve high yield, resulting in large quantities of microplastic (MP) pollution in agroecosystem. However, studies focusing specifically on the diversity of MP-degrading enzymes and related microbial communities have yet to be conducted. Here, we established a soil microcosmic incubation with addition of 5% (w/w) conventional (low-density polyethylene (LDPE)) and biodegradable (blend of polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT)) MPs for incubation 90 days. The DNA samples extracted from soils and plastisphere of MPs were examined by metagenomics and genome binning methods, specifically targeting carbohydrate-active enzymes (CAZymes) and plastic-degrading enzymes (PDZymes). The results revealed that plastisphere of MPs exhibited significantly distinct patterns of CAZymes and PDZymes from soils, and abundances of all examined exoenzymes were higher in plastisphere than those in soils. Plastisphere of LDPE-MPs selectively enriched proteases and alkane monooxygenase (alkB), and required families of carbohydrate-binding module (CBM) to increase the binding of CAZymes with MPs. Dissimilarly, diverse CAZymes with high abundances were observed in the plastisphere of PBAT-PLA MPs and esterases were important indicative PDZymes for PBAT-PLA degradation. The enriched exoenzymes in plastisphere of LDPE-MPs were mainly assigned to Actinobacteria while Proteobacteria with higher abundance in plastisphere of PBAT-PLA MPs containing most indicative exoenzymes. Moreover, a high-quality genome classified as Amycolatopsis japonica was reconstructed and found to contain one or more gene copies of indicative exoenzymes for polyethylene. Two novel genomes classified as Sphingomonas were selectively enriched in plastisphere of PBAT-PLA MPs and contained diverse genes encoding degrading exoenzymes. Taken together, our study highlighted the CAZymes and PDZymes can be exploited as potent microbial strategies for solving MPs pollution in croplands. [Display omitted] • MPs enriched a wide range of CAZymes and PDZymes compared to soils. • PE required CBM to enhance enzyme hydrolysis and selected proteases and alkane monooxygenase. • Diverse CAZymes and esterases as the important indicator act on BD biodegradation. • The potential PE degraders assigned to Actinobacteria while members of Proteobacteria enriched in BD. • Amycolatopsis japonica and Sphingononas were identified as the potential degraders for PE and BD, respectively. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have become the major global concern due to their adverse effects on the environment, human health, and hygiene. These complex molecules have numerous toxic impacts on human well-being. This review focuses on the methods for chemically quantifying and identifying MPs in real-time samples, as well as the detrimental effects resulting from exposure to them. Biopolymers offer promising solutions for reducing the environmental impact caused by persistent plastic pollution. The review also examines the significant progress achieved in the preparation and modification of various biobased polymers, including polylactic acid (PLA), poly(ε-caprolactone) (PCL), lignin-based polymers, poly-3-hydroxybutyrate (PHB), and poly(hydroxyalkanoates) (PHA), which hold promise for addressing the challenges associated with unplanned plastic waste disposal. [Display omitted] • Chemical quantification and identification methods of microplastics are discussed. • Detrimental effects of microplastics on biomass has been discussed. • The recent progress in the preparation of biobased polymers PLA, PCL, Lignin, PHB, PHA has been reviewed. • Future outlooks and challenges for the use of biopolymers in plastic manufacturing are discussed. [ABSTRACT FROM AUTHOR]

The usage of biodegradable plastics is expanding annually due to worldwide plastic limits, resulting in a substantial number of microplastics (MPs) particles formed from biodegradable plastic products entering the aquatic environment. Until now, the environmental behaviors of these plastic product-derived MPs (PPDMPs) have remained unclear. In this work, commercially available polylactic acid (PLA) straws and PLA food bags were used to evaluate the dynamic aging process and environmental behavior of PLA PPDMPs under UV/H 2 O 2 conditions. By combining scanning electron microscopy, two-dimensional (2D) Fourier transform infrared correlation spectroscopy (COS) and X-ray photoelectron spectroscopy, it was determined that the aging process of the PLA PPDMPs was slower than that of pure MPs. The 2D-COS analysis revealed that the response orders for the functional groups on the PLA MPs differed during the aging process. The results demonstrated that the oxygen-containing functional groups of the PLA PPDMPs were the first to react. Subsequently, the –C–H and –C–C− structural responses began, and the polymer backbone was ruptured by the aging process. However, the aging of the pure-PLA MPs started with a brief oxidation process and then breakage of the polymer backbones, followed by continuous oxidation. Moreover, compared to the PLA PPDMPs, the pure-PLA MPs exhibited a greater adsorption capacity, which was increased by 88% after aging, whereas those of the two PPDMPs only increased by 64% and 56%, respectively. This work provides new insights into the behaviors of biodegradable PLA MPs in aquatic environments, which is critical for assessing the environmental risks and management policies for degradable MPs. [Display omitted] • The aging process of PLA plastic product-derived MPs was slower than pure-PLA MPs. • The UV/H 2 O 2 aging process significantly increased the adsorption capacity of PLA MPs. • Product-derived MPs had lower adsorption capacity for pollutants compared to pure MPs. • 2D-COS demonstrated the dynamic aging process of PLA product-derived MPs and pure-PLA MPs. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) accounts for approximately 45% of the global market of biodegradable plastics. Using Caenorhabditis elegans as an animal model, we examined the effect of long-term exposure to PLA microplastic (MP) on reproductive capacity and the underlying mechanism. Brood size, number of fertilized eggs in uterus, and number of hatched eggs were significantly reduced by exposure to 10 and 100 μg/L PLA MP. Number of mitotic cells per gonad, area of gonad arm, and length of gonad arm were further significantly decreased by exposure to 10 and 100 μg/L PLA MP. In addition, exposure to 10 and 100 μg/L PLA MP enhanced germline apoptosis in the gonad. Accompanied with the enhancement in germline apoptosis, exposure to 10 and 100 μg/L PLA MP decreased expression of ced-9 and increased expressions of ced-3 , ced-4 , and egl-1. Moreover, the induction of germline apoptosis in PLA MP exposed nematodes was suppressed by RNAi of ced-3 , ced-4 , and egl-1 , and strengthened by RNAi of ced-9. Meanwhile, we did not detect the obvious effect of leachate of 10 and 100 μg/L PLA MPs on reproductive capacity, gonad development, germline apoptosis, and expression of apoptosis related genes. Therefore, exposure to 10 and 100 μg/L PLA MPs potentially reduces the reproductive capacity by influencing the gonad development and enhancing the germline apoptosis in nematodes. [Display omitted] • Exposure to 10 and 100 μg/L PLA MP reduced reproductive capacity in nematodes. • PLA MPs induced damage on gonad development and enhanced germline apoptosis. • PLA MP exposure increased ced-3 and ced-4 expressions and decreased ced-9 expression. • Leachate of 10 and 100 μg/L PLA MP did not cause obvious reproductive toxicity. [ABSTRACT FROM AUTHOR]

Biodegradable plastics have been widely used to replace conventional plastics to minimize environmental impacts of plastic packaging. However, before biodegradable plastics decompose in the environment, they could pose a threat to terrestrial and aquatic creatures by acting as vectors of contaminants in the food chain. In this study, conventional plastic bags (CPBs) made of polyethylene and biodegradable plastic bags (BPBs) made of polylactic acid were examined for their heavy metal adsorption. Effects of solution pHs and temperatures on adsorption reactions were investigated. Because of a larger BET surface area, presence of oxygen-containing function groups, and smaller crystallinity, the heavy metal adsorption capacities of BPBs are significantly larger than those of CPBs. Among Cu (up to 791.48 mg⋅kg−1), Ni (up to 60.88 mg⋅kg−1), Pb (up to 1414.58 mg⋅kg−1), and Zn (up to 295.17 mg⋅kg−1), Pb and Ni show the largest and the lowest extents of adsorption onto the plastic bags, respectively. In the different waterbodies in nature, Pb adsorption on the CPBs and the BPBs were 318.09–379.91 and 528.41–764.22 mg⋅kg−1, respectively. Consequently, Pb was selected as the target contaminant in the desorption experiments. After Pb was adsorbed onto the CPBs and the BPBs, Pb could be completely desorbed and released into simulated digestive systems in 10 h. In conclusion, BPBs could be potential vectors of heavy metals, and their suitability as a substitute for CPBs must be thoroughly investigated and confirmed. [Display omitted] • Polylactic acid as a major component of biodegradable plastic bags was recognized. • Adsorption capacity of Pb on plastic bags exceeds those of other heavy metals. • Significantly pH affects adsorption behaviors of heavy metals on the plastics. • This article is the first one to compare desorption of heavy metals on CPBs and BPBs. • Pb adsorbed on plastic bags could completely released into digestive simulators. [ABSTRACT FROM AUTHOR]

Biodegradable plastic is considered one of the most promising alternatives to agricultural mulch. However, the impact of biodegradable microplastics on agricultural ecosystems is still lacking. We conducted a controlled experiment with polylactic acid microplastics (PLA MPs) to examine the effects of biodegradable plastic on soil properties, corn growth, the microbial community and hotspots of enzyme activity. The results showed that PLA MPs in soil significantly reduced the soil pH value but increased the soil C:N ratio. High levels of PLA MPs significantly reduced the biomass of plant shoots and roots as well as chlorophyll, leaf C and N and root N contents. PLA MPs increased bacterial abundance but decreased the abundance of dominant fungal taxa. As the level of PLA MPs increased, the soil bacterial community structure became more complex, while the fungal community became more singular. The results of the in situ zymogram showed that low levels of PLA MPs increased the hotspots of enzyme activity. The effect of PLA MPs on enzyme activity hotspots was regulated by a combination of soil properties and microbial diversity. Generally, the addition of PLA MPs at high concentrations will have a negative impact on soil characteristics, soil microbials and plant growth in a short period of time. Therefore, we should be aware of the potential risks of biodegradable plastic to agricultural ecosystems. [Display omitted] • PLA MPs significantly reduced soil pH but increased the soil stoichiometric C:N ratio. • High levels of PLA MPs had significant negative effects on plant growth. • PLA MPs can pose a threat to soil microbial and soil health conditions in the short term. [ABSTRACT FROM AUTHOR]

Recently, feed spacer research for improving the performance of a membrane module has adopted three-dimensional (3D) printing technology. This study aims to improve the performance of membrane feed spacers by using various materials and incorporating 3D printing. The samples were fabricated after modeling with 3D computer-aided design (CAD) software to investigate the mechanical strength, water flux, reverse solute flux, and fouling performances. This research was performed using acrylonitrile butadiene styrene (ABS), polypropylene (PP), and natural polylactic acid (PLA) as printing material, and the spacer model was produced using a diamond-shaped feed spacer, with a commercially available product as a reference. The 3D printed samples were initially compared in terms of size and precision with the 3D CAD model, and deviations were observed between the products and the CAD model. Then, the spacers were tested in terms of mechanical strength, water flux, reverse solute flux, and fouling (alginate-based waste water was used as a model foulant). Although there was not much difference among the samples regarding the water flux, better performances than the commercial product were obtained for reverse solute flux and fouling resistance. When comparing the prominent performance of natural PLA with the commercial product, PLA was found to have approximately 10% less fouling (based on foulant volume per unit area and root mean square roughness values), although it showed similar water flux. Thus, another approach has been introduced for using bio-degradable materials for membrane spacers. [ABSTRACT FROM AUTHOR]

Bioplastics made of renewable sources provide an excellent alternative to fossil-based materials. However, similar or greater quantities of plastic additives than fossil-based plastics are used in the formulations of bioplastics to improve their performance and barrier properties. Nowadays, there is an increasing concern about sources of chemical exposure. However, there is an important knowledge gap regarding complex additive mixtures, particularly in bio-based materials. In this study, we have characterised the presence of plastic additives in single-use materials (collected from retail shops in Spain), which are made of the most common bio-based biodegradable materials, poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB), in contrast with a fossil-based plastic material that is extensively made from high-density polyethylene (HDPE). The approach consisted of the pulverization of material in the nano-micro range (100 nm-10 μm), with the materials being extracted using different solvents and ultrasonic-assisted solvent extraction (UASE). 100% of the additives in the material cannot be extracted, but since they were performed in the same condition for all materials can inform about the fingerprint of primary organics and the relative abundances between the different materials. The extracts were analysed by high-performance liquid chromatography coupled with high-resolution mass spectrometry equipped with a heated electrospray ionisation source operated in positive and negative ionisation conditions (HPLC-HESI(+/−)-HRMS), separately, using a suspect screening approach. A total number of 203 additives were tentatively identified (confidence level 2) in the bioplastics items of this study. An average of 123 plastic additives were found in PLA items and 121 in PHB items. Plasticisers were the most abundant additives; the phthalates group was the most commonly found, while 63 plastic additives were confirmed by standards and quantified. In parallel, the cytotoxicity of plastic particles in terms of cell viability and oxidative stress was studied using A549 alveolar basal epithelial cells, and the toxicity of the different extracts was also established using HepG2 adenocarcinoma cells. The main results of this study demonstrate that the plastic particles did not show a significant reduction in cell viability, but oxidative stress was significant, with PLA being the material that showed the highest effect. On the other hand, extracts of plastic particles did not show inhibition of cell viability except for HDPE extract, but the different extracts produced oxidative stress, with PLA showing the highest effect. Although the item showing the highest concentrations of additives was the extract of PLA material while also showing the most elevated oxidative stress, the low migration of toxicants from plastic materials ensures their safe use. However, this also supports the idea that bioplastics can contain many toxic substances in their formulations, some of which are unknown and should be studied in more depth. PLASTIC ADDITIVES GROUPS TENTATIVELY IDENTIFIED IN BIOPLASTICS. [Display omitted] • Plastic additives in bioplastics of single-use items were characterised. • A total number of 123 additives were tentatively identified. • Cell viability and oxidative stress of bioplastics and additives extracts were studied. • Polylactic acid showed the highest oxidative stress. [ABSTRACT FROM AUTHOR]

Marine plastic pollution caused by non-biodegradable polymers is a major worldwide concern. So-called "biodegradable" polymers should reduce plastic pollution in the environment by the safeguard of biodegradation. However, many polyesters degrade very slowly in seawater. We therefore designed a systematic library of "breaking points" that are installed into a polylactide backbone and simulated their degradation mechanisms, including internal and external S N 2 mechanisms, Addition-Elimination (AE) mechanisms, and RNA-inspired mechanisms. The breaking points are composed of phosphoesters with pendant nucleophiles directly at the P-atom, or structurally similar silicones, or side-chain functional polyesters. All P-containing breaking points react via the RNA-inspired mechanism, while Si-containing linkers undergo decomposition via the A-E mechanism. For C-containing linkers, only when a long pendant chain (4 carbon atoms) is present can the reaction proceed via the RNA-inspired mechanism. In cases of shorter pendants, the Addition-Elimination (AE) mechanism is energetically favorable. We believe that these calculations will pave the way for the synthesis of exceptionally seawater-degradable polyesters in the future that can act as a safeguard to prevent microplastic formation after eventual littering. [Display omitted] • Simulation of degradation of polylactide derivatives with specially designed breaking points. • Influence of breaking points structure on polymer stability. • All phosphoester-based breaking points degraded by an intramolecular RNA-inspired transesterification. • Precise control over the degradation of polylactide by the structure of breaking points. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Overview of microbial bioplastics. • Leads and hurdles of microbial bioplastics were discussed. • Diverse applications were discussed. [ABSTRACT FROM AUTHOR]

As plastic consumption has increased, environmental problems associated with the accumulation of plastic wastes have started to emerge. These include the non-degradability of plastic and its disintegration into sub-micron particles. Although some biodegradable plastic products have been developed to relieve the landfill and leakage burden, a significant portion of discarded plastics are inevitably still incinerated. The concern here is that incinerating plastics may result in the emission of toxic volatile organic compounds (VOCs). Moreover, lack of policy and the limited market share contributes to the indiscriminate discarding of biodegradable plastics, whereby it is mixed and subsequently incinerated with non-degradable plastics. The aim of this study was therefore to qualitatively and quantitatively analyze the VOCs emitted from both non-degradable and biodegradable plastics during combustion employing gas chromatography mass spectrometry. Here, non-degradable poly(vinyl chloride) and poly(ethylene terephthalate) emitted 10–115 and 6–22 ppmv of VOCs, respectively. These emission levels were more than 100 times higher than the VOC concentrations of 0.1–0.5 and 0.1–1.8 ppmv obtained for biodegradable polyhydroxyalkanoate and polylactic acid, respectively. Notably, due to the presence of a repeating butylene group in both non-degradable and biodegradable plastics, 1,3-butadiene accounted for the highest concentration among the VOCs identified, with concentrations of 6–116 ppmv and 0.5–558 ppmv obtained, respectively. During the evaluation of gas barrier films employed for food packaging purposes, non-degradable aluminum-coated multilayered films emitted 9–515 ppmv of VOCs, compared to the 2–41 ppmv VOCs emitted by biodegradable nanocellulose/nanochitin-coated films. Despite the significantly lower levels of VOCs emitted during the incineration of biodegradable plastics, this does not represent suitable waste treatment solution because VOCs are still emitted during incomplete combustion. This study aims to encourage further research into diverse combustion conditions for plastics and stimulate discussions on the fate of discarded plastics. [Display omitted] • Incineration of non-degradable and biodegradable plastics to determine volatile organic compounds (VOCs). • Non-degradable poly(vinyl chloride) and poly(ethylene terephthalate) emit VOCs. • Clean burning of polyhydroxyalkanoate and poly(lactic acid) produced minimal VOCs. • Poly(butylene succinate) and poly(butylene adipate -co- terephthalate) emit 1,3-butadiene. [ABSTRACT FROM AUTHOR]

Both biodegradable and nondegradable plastics are widely used. However, their interactions with petroleum hydrocarbons (PHs) have not been sufficiently studied. In this study, a type of biodegradable [polylactic acid (PLA)] and five types of nondegradable microplastics [polyamide (PA), polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), and polyvinyl chloride (PVC)] were selected to investigate the sorption and desorption mechanisms of PHs. The sorption kinetics of the six types of microplastics followed a pseudo-second-order kinetics model (R2 ranged from 0.956 to 0.999) and indicated that chemical sorption dominated the sorption process. The key rate-controlling steps of the sorption of PHs on microplastics were intraparticle diffusion and liquid film diffusion. The sorption capacity of PHs on microplastics followed the order of PA > PE > PS > PET > PLA > PVC. The difference in sorption capacity might be due to the crystallinity, and rubber or glass state of the microplastics. In addition, all types of microplastics exhibited reversible sorption without noticeable desorption hysteresis. No obvious differences were observed in the sorption and desorption of PHs between biodegradable and nondegradable microplastics. Both biodegradable and nondegradable microplastics could sorb/desorb PHs and serve as transportation vectors. • Kinetics and isotherms were elucidated. • The sorption conformed to pseudo-second-order model. • Sorption capacity followed the order PA > PE > PS > PET > PLA > PVC. • The desorption was reversible, without hysteresis. • PLA displayed similar sorption and desorption mechanisms as PA, PE, PET, PVC, and PS. [ABSTRACT FROM AUTHOR]

Microplastics have become a contaminant of increasing concern in soils. Although biodegradable plastics were considered as alternatives of traditional plastics, some evidence showed that biodegradable plastics might produce more microplastics. Until now, the effect of biodegradable microplastics on soil functions and processes, as well as microbial communities is uncertain. Based on high throughput sequencing, enzymatic activity assay and dynamic analysis of soil carbon and nitrogen, we investigated the effects of biodegradable polylactic acid microplastics (PLA MPs) on soil microbiota and related ecological processes under conditions of high or low carbon content. The results showed that PLA MPs had no significant effect on the overall diversity and composition of bacterial communities or related ecosystem functions and processes. However, co-occurrence network analysis revealed that PLA MPs impacted the interactions between constituent species, which might have legacy effect on soil bacterial communities and functions. Our data also revealed that PLA MPs could trade off the priming effect of carbon source. Our results provided an integrated picture in understanding the effects of PLA MPs on soil microbes, properties and ecological functions, which will help to further understand the effects of MPs on terrestrial ecosystems. Image 1 • 2% PLA MPs did not impact soil nutrient pool and ecological functions. • A faster ammonia transformation rate was observed in PLA MPs amended soil. • The interaction among bacteria has been changed with the addition of PLA MPs. • Different effect of PLA MPs on soil under different carbon content was observed. [ABSTRACT FROM AUTHOR]