Search

[Display omitted] • A bioplastic was synthesized from citrus peel biomass. • Bioplastic is safely degradable and recyclable, enabling a perfect closed-loop cycle. • Bioplastics exhibit unique antioxidant and antimicrobial properties. • Bioplastics can extend the shelf life of perishable fruits. • The universality of this strategy was validated in a wide range of fruit peels. The development of biodegradable antimicrobial bioplastics for food packaging holds great promise for solving the pollution and safety problems caused by petrochemical plastics and spoiled food. Herein, a natural active-bioplastic synthesized from citrus peel biomass is presented for perishable fruit preservation. These plastics are characterized by the nanoscale entanglement and recombinant hydrogen bonding between the endogenous pectin, polyphenols and cellulose micro/nanofibrils. They have attractive flexibility, tensile strength, gas barrier properties and antimicrobial activities, and can effectively extend the shelf life of perishable fruits such as banana and mango when used as food packaging. Cytotoxicity, degradability tests and life-cycle assessment show that these plastics had excellent nontoxicity and can be safely degraded or easily recycled. This work demonstrates a sustainable strategy for converting peel waste into eco-friendly bioplastics, providing a unique and novel insight into radically reducing the pollution and life-health threats posed by petrochemical plastics and spoiled food. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nutrient stresses were applied to Cupriavidus necator growing on carbon dioxide. • Nitrogen starvation induced a PHB accumulation of 54% of total cell dry weight. • The carbon conversion yield into PHB reached a maximum of 85% under nitrogen stress. • Single-stage starvation was more effective than double-stages for PHB production. • Gas transfer enhancement in the fed-batch mode could improve the polymer yield. Cupriavidus necator is a facultative chemolithoautotrophic bacterium able to convert carbon dioxide into poly-3-hydroxybutyrate. This is highly promising as the conversion process allows the production of sustainable and biodegradable plastics. Poly-3-hydroxybutyrate accumulation is known to be induced by nutrient starvation, but information regarding the optimal stress conditions controlling the process is still heterogeneous and fragmentary. This study presents a comprehensive comparison of the effects of nutrient stress conditions, namely nitrogen, hydrogen, phosphorus, oxygen, and magnesium deprivation, on poly-3-hydroxybutyrate accumulation in C. necator DSM545. Nitrogen starvation exhibited the highest poly-3-hydroxybutyrate accumulation, achieving 54% of total cell dry weight after four days of nutrient stress, and a carbon conversion efficiency of 85%. The gas consumption patterns indicated flexible physiological mechanisms underlying polymer accumulation and depolymerization. These findings provide insights into strategies for efficient carbon conversion into bioplastics, and highlight the key role of C. necator for future industrial-scale applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • PLA/PBAT underwent modification through covalent bonding with enzymes. • The anaerobic co-digestion performance of the modified biodegradable plastic with food waste was assessed and examined. • The degradation of enzyme modified biodegradable plastic could increase from 5.21% to 29.70% compare to unmodified plastic. • The hydrolysis process was enhanced by the presence of highly active Bacteroidota and Thermotogota. A modified biodegradable plastic (PLA/PBAT) was developed by through covalent bonding with proteinase K, porcine pancreatic lipase, or amylase, and was then investigated in anaerobic co-digestion mixed with food waste. Fluorescence microscope validated that enzymes could remain stable in modified the plastic, even after co-digestion. The results of thermophilic anaerobic co-digestion showed that, degradation of the plastic modified with Proteinase K increased from 5.21 ± 0.63 % to 29.70 ± 1.86 % within 30 days compare to blank. Additionally, it was observed that the cumulative methane production increased from 240.9 ± 0.5 to 265.4 ± 1.8 mL/gVS, and the methane production cycle was shortened from 24 to 20 days. Interestingly, the kinetic model suggested that the modified the plastic promoted the overall hydrolysis progression of anaerobic co-digestion, possibly as a result of the enhanced activities of Bacteroidota and Thermotogota. In conclusion, under anaerobic co-digestion, the modified the plastic not only achieved effective degradation but also facilitated the co-digestion process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compostable plastics show no impact on full scale composting process. • Safety and agronomic requirements of organic farming met. • Composting plastics with biowaste has less environmental impacts than incineration. The incorporation of representative commercial compostable materials into a full-scale open-air windrow composting process in an industrial site using household-separated biowaste was investigated. Two batches out of the same initial biowaste mixture were studied, one as control and the other containing initially 1.28 wt% of certified compostable plastics. No significant differences in the composting process were revealed. Compostable plastics exhibited a 98 wt% mass loss after 4 months, aligning with industrial composting times. The evolution of the morphology of the materials unveiled polymer specific degradation mechanisms. Both Safety requirements for organic farming were met. Ecotoxicity tests showed no adverse effects, agronomic fertilizing and amending quality was high, the materials compost even enhancing barley growth. The ecological impact assessment demonstrated an advantage for composting over incineration for seven of the eight indicators. In conclusion, this study shows the successful integration of compostable materials into industrial composting, upholding product safety and quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metabolic engineering of E. coli for efficient production of P(3-HP) bioplastic. • Overexpression of phasin and cell division protein increased P(3-HP) accumulation. • Engineered E. coli produced 80 g/L of P(3-HP) with cellular content exceeding 72 %. • P(3-HP) from recombinant strains exhibited elastomeric or flexible plastics traits. This study focuses on the development of a scalable method for producing poly(3-hydroxypropionate), a homopolymer with significant physico-mechanical properties, through the use of metabolically-engineered Escherichia coli K12 (MG1655) and externally supplied 3-hydroxypropionate. The polymer synthesis pathway was established and optimized through synthetic biology techniques, including the effects of overexpressing phasin and cell division proteins. The optimized strain achieved unprecedented production titers of 9.5 g/L in flask cultures and 80 g/L in fed-batch bioreactors within 45 h. The analysis of poly(3-hydroxypropionate) polymer properties revealed it possesses excellent elasticity (Young's modulus < 6 MPa) and tensile strength (∼80 MPa), positioning it within the category of elastomers or flexible plastics. These findings suggest a viable path for the sustainable, large-scale production of the poly(3-hydroxypropionate) biopolymer. [ABSTRACT FROM AUTHOR]

[Display omitted] • The most effective pretreatment condition was 162.5 g OH–/kg BP, 7.75 h, and 90 °C. • The response surface graph showed that pretreatment was more effective at smaller sizes. • The reduction in particle size also increased the CH 4 production by 10–24%. • With only 40% PLA solubilization, 91% CH 4 production yield was achieved. • FTIR results, particularly changes in –OH bands, support the findings. The fragmentation of bioplastics (BPs) before pretreatment and anaerobic digestion is conducted for higher efficiency; however, based on the literature, the size reduction varies widely. In this study, initially, various combinations of thermal-alkaline pretreatments were applied at different strengths to the polylactic acid (PLA) in three groups (<0.5, 0.5 < size < 1.0, and 1.0 < size < 2.0 mm). After pretreatment, the solubilization of PLA was increased to 11.5–40.0 % using alkaline dosage and temperature ranging from 50 to 200 g OH–/kg BP, 60–100 °C, respectively, in a 1–10 h timeframe. The results were statistically proved using a 3D response surface graph, where the pretreatment was more effective for smaller particle sizes. The reduction in particle size also increased the CH 4 production, which was more pronounced at the strong pretreatment (24 % increment vs. 10–15 %). Computed results indicated 44–86 % conversion of pretreated PLA particles to CH 4 , supported by Fourier transform infrared spectroscopy analysis, especially focusing on the intensity of –OH bands. [ABSTRACT FROM AUTHOR]

[Display omitted] • Constitutive promoter P cpc560 has a high expression level even without any inducer. • The developed strain expressing phaCAB with P cpc560 produced 226 mg L−1 of PHB. • Supplying acetate is more effective than applying stresses in producing PHB. • Addition of 1 g L−1 of acetate resulted in 607.2 mg L−1 of PHB, a 2.7-fold increase. • The cost of additive for PHB production could be reduced by more than 300 times. Bioplastic production using cyanobacteria can be an effective strategy to cope with environmental problems caused by using petroleum-based plastics. Synechococcus elongatus UTEX 2973 with heterogeneous phaCAB can produce bioplastic polyhydroxybutyrate (PHB) with a high CO 2 uptake rate. For cost-effective production of PHB in S. elongatus UTEX 2973, phaCAB was expressed by the constitutive P cpc560 , resulting in the production of 226 mg/L of PHB by only photoautotrophic cultivation without the addition of inducer. Several culture conditions were applied to increase PHB productivity, and when acetate was supplied at a concentration of 1 g/L as an organic carbon source, productivity significantly increased resulting in 607.2 mg/L of PHB and additive cost reduction of more than 300 times was achieved compared to IPTG. Consequently, these results suggest the possibility of cyanobacteria as an agent that can economically produce PHB and as a solution to the problem of petroleum-based plastics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halophilic bacteria accumulate osmolytes in the cytoplasms to adapt to osmotic pressure. • The osmolytes accumulated by Halomonas sp. YJPS3-3 are P3HB. • Developed gamma-irradiated Halomonas mutants boost PHA by 11%. • Creating halotolerance enhanced mutations in halophiles is a pioneering approach. Polyhydroxyalkanoates (PHA) have emerged as a promising bio-compound in the industrial application due to their potential to replace conventional petroleum-based plastics with sustainable bioplastics. This study focuses on Halomonas sp. YJPS3-3, a halophilic bacterium, and presents a novel approach to enhance PHA production by exploiting its salt tolerance toward PHA biosynthesis. Through gamma irradiation-induced mutants with enhanced salt tolerance from 15% NaCl to 20% NaCl, mutant halo6 showing a significant 11% increase in PHA yield, was achieved. Moreover, the mutants displayed not only higher PHA content but also remarkable cell morphology with elongation. In addition, this research unravels the genetic determinants behind the elevated PHA content and identifies a corresponding shift in fatty acid composition favoring PHA accumulation. This novel mutant obtained from gamma irradiation with enhanced salt tolerance in halophilic bacteria opens up new avenues not only for the bioplastic industry but also for applications in the production of high-value metabolites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Engineered G. thermoglucosidasius produces polymer-grade lactic acid at 60 °C. • Rational and semi-rational design strategies are used to reprogram the chassis. • Potential genetic targets are revealed to improve the production performance. • The highest lactic acid production is achieved in thermophile strains over 55 °C. The production and application of biodegradable polylactic acid are still severely hindered by the cost of its polymer-grade lactic acid monomers. High-temperature biomanufacturing has emerged as an increasingly attractive approach to enable low-cost and high-efficiency bulk chemical production. In this study, thermophilic Geobacillus thermoglucosidasius was reprogrammed to obtain optically pure l -lactic acid- and d -lactic acid-producing strains, G. thermoglucosidasius GTD17 and GTD7, by using rational metabolic engineering strategies including pathway construction, by-product elimination, and production enhancing. Moreover, semi-rational adaptive evolution was carried out to further improve their lactic acid synthesis performance. The final strains GTD17-55 and GTD7-144 produce 151.1 g/L of l -lactic acid and 153.1 g/L of d -lactic acid at 60 °C, respectively. In consideration of the high temperature, productive performance of these strains is superior compared to the state-of-the-art industrial strains. This study lays the foundation for the low-cost and efficient production of biodegradable plastic polylactic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • Industrial scale PHB production model using various carbon sources was developed. • Techno-economic analysis was used to assess the effect of raw materials on cost. • Cheapest PHB unit production cost was 3.63 $/kg when fructose was consumed. • Sensitivity analysis show that the price of H 2 effects PHB price the most. • Using CO 2 and formate for producing PHB can be feasible in the bioplastic market. Polyhydroxybutyrate (PHB) is a biodegradable polymer that has potential to replace petroleum-derived plastics. However, the commercialisation of PHB is hindered by high production costs. In this study, the material flow and economics of an industrial scale PHB production process using fructose, formic acid and carbon dioxide (CO 2) as carbon sources were simulated and analysed. The lowest breakeven price of 3.64 $/kg PHB was obtained when fructose was utilized as carbon source. When formic acid and CO 2 were used, the breakeven price was 10.30 and 10.24 $/kg PHB due to raw material cost, respectively. Although using formic acid and CO 2 is more expensive, they meet the emerging sustainable needs for plastic production and contribute to the circular economy via CO 2 fixation. This study suggests that the use of formic acid and CO 2 as feedstock for PHB production has potential to become competitive in the bioplastic market with further research. [ABSTRACT FROM AUTHOR]

[Display omitted] • PET hydrolase (WCCG) delayed the humification of composting. • WCCG altered the microbial community and decreased the relative abundance of thermophilic genus. • Plastic-degrading microbiota are enriched in plastisphere. • WCCG and plastic-degrading microbiota explain the degradation of PET-MPs during high-temperature composting. This research aims to explore the degradation properties of polyethylene terephthalate (PET) by PET hydrolase (WCCG) in high-temperature composting and its impact on microbial communities. PET degradation, composting parameters and microbial communities were assessed in 220 L sludge composters with PET and WCCG using high-throughput sequencing. Results showed that WCCG addition led to a deceleration of the humification process and a reduction in the relative abundance of thermophilic genera. Potential PET degrading microbiota, e.g. Acinetobacter , Bacillus , were enriched in the plastisphere in the composters where PET reduced by 26 % without WCCG addition. The external introduction of the WCCG enzyme to compost predominantly instigates a chemical reaction with PET, concurently curtailing the proliferation of plastic-degrading bacteria, leading to a 35 % degradation of PET. Both the WCCG enzyme and the microbiota associated with plastic-degradation showed the potential for reducing PET, offering a novel method for mitigating pollution caused by environmental microplastics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compost aging affects the physicochemical properties of biochar. • Addition of PS increased the concentration of EPFRs. • Biochar increased the bacterial community in compost. • The concentration of EPFRs affect the degradation efficiency. Simulation of microbial aging biochar in compost is an important index for evaluating the biochar degradation efficiency of antibiotics. In this study, biochar was prepared by adding microplastics (MPs) to sludge, and the degradation effect of biochar/(peroxymonosulfate, PMS) on antibiotics was evaluated during the compost aging process of biochar. After the compost aging of biochars, the antibiotic degradation efficiency of HPBC500, HPBC500 + polystyrene (PS), HPBC900/PMS, and HPBC900 + PS/PMS decreased by 6.47, 15.2, 10.16, and 10.33 %, respectively. Environmentally persistent free radicals (EPFRs) and defect structure were the main contributors to the activation of PMS. EPFRs produced through PS pyrolysis of biochar exhibited strong reactivity but poor stability during the degradation of antibiotics. Biochar enhanced the growth of microorganisms in compost but reduced its specific surface area. The antibiotic degradation efficiency of the biochar was positively correlated with the concentration of EPFRs. This study elucidated the durability of different biochar toward antibiotic degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biodegradable plastics (30 μm) improved the methane production of the anaerobic system (> 57%). • The digestate with biodegradable plastics (40 μm) inhibited the elongation of seed roots. • Biodegradable plastics increased abundance of Methanobacterium and Methanosaeta. • Biodegradable plastics (≥ 40 μm) should be shredded to less than 20 × 20 mm. The effects of biodegradable plastics of different thicknesses (30 and 40 μm) and sizes (20 × 20, 2 × 2, and 1 × 1 mm) on anaerobic digestion of food waste and digestate phytotoxicity were investigated. Methane productions (38 days) for the groups with 20 × 20, 2 × 2, and 1 × 1 mm of 30 μm plastics were 92.46, 138.27, and 259.95 mL/gVS removal , respectively which are nearly 58 % higher than the control group (58.86 mL/gVS removal). Methane production in 40 μm plastics groups was lower than in 30 μm groups of equal size. All sizes of 30 µm plastics promoted substrate hydrolysis, acidification, and relative abundance of key hydrolytic bacteria and methanogens. Phytotoxicity tests results showed that seed root elongation was inhibited in groups with 40 μm plastics. In conclusion, 30 μm biodegradable plastics were more suitable for anaerobic digestion with food waste than 40 μm. [ABSTRACT FROM AUTHOR]

[Display omitted] • PHB is produced under nutrients deficient condition with only CO 2 /CH 4 as carbon source. • Co-culture or mixed culture is a promising method to improve PHAs production from CO 2 /CH 4. • Organic carbon addition can enhance some strains using CO 2 /CH 4 to produce copolymers. The currently used plastics are non-biodegradable, and cause greenhouse gases (GHGs) emission as they are petroleum-based. Polyhydroxyalkanoates (PHAs) are biopolymers with excellent biodegradability and biocompatibility, which can be used to replace petroleum-based plastics. A variety of microorganisms have been found to synthesize PHAs by using typical GHGs: carbon dioxide and methane as carbon sources. Converting carbon dioxide (CO 2) and methane (CH 4) to PHAs is an attractive option for carbon capture and biodegradable plastic production. In this review, the microorganisms capable of using CO 2 and CH 4 to produce PHAs were summarized. The metabolic mechanism, PHAs production process, and the factors influencing the production process are illustrated. The currently used optimization techniques to improve the yield of PHAs are discussed. The challenges and future prospects for developing economically viable PHAs production using GHGs as carbon source are identified. This work provides an insight for achieving carbon sequestration and bioplastics based circular economy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recombinant yeast strains effectively hydrolyse single-use bioplastic items. • rCLE1 is modified during yeast expression and resulted in increased hydrolysis. • rCLE1 preferentially hydrolyses specific polymers in bioplastic blends. • Bioplastic blends could be highly susceptible to enzymatic hydrolysis. • Enzyme adsorption and product inhibition are bottlenecks to hydrolysis. • Future work would integrate enzymatic hydrolysis in waste management settings. Single-use bioplastic items pose new challenges for a circular plastics economy as they require different processing than petroleum-based plastics items. Microbial and enzymatic recycling approaches could address some of the pitfalls created by the influx of bioplastic waste. In this study, the recombinant expression of a cutinase-like-enzyme (CLE1) was improved in the yeast Saccharomyces cerevisiae to efficiently hydrolyse several commercial single-use bioplastic items constituting blends of poly(lactic acid), poly(1,4-butylene adipate -co- terephthalate), poly(butylene succinate) and mineral fillers. The hydrolysis process was optimised in controlled bioreactor configurations to deliver substantial monomer concentrations and, ultimately, 29 to 78% weight loss. Product inhibition studies and molecular docking provided insights into potential bottlenecks of the enzymatic hydrolysis process, while FT-IR analysis showed the preferential breakdown of specific polymers in blended commercial bioplastic items. This work constitutes a step towards implementing enzymatic hydrolysis as a circular economy approach for the valorisation of end-of-life single-use bioplastic items. [ABSTRACT FROM AUTHOR]

[Display omitted] • First study of microbial acclimation effects on bioplastics anaerobic digestion. • Inoculum acclimation to the substrate improves anaerobic digestion of bioplastics. • Enhanced growth of starch and PLA degraders increases bioplastic degradation. • Acclimation increased biogas production of starch-based bioplastic by 52%. • Acclimation increased biogas production of PLA-based bioplastic by 97%. This paper reports the results of a novel study of microbial acclimatization for bioplastics anaerobic degradation and conversion into biogas. Three sequential anaerobic digestion (AD) runs were carried out to favour microbial acclimatization to two different bioplastics, starch-based (SBS) and polyactic-acid (PLA). AD of SBS and PLA bioplastics was favoured by the acclimatization of the inoculum to the substrate after each run of AD. SBS conversion into biogas increased by 52 % (from 94 to 143 NL kgVS-1) and it was correlated with the enhanced growth of starch degrading bacteria such as Hydrogenispora, Halocella and Haloplasma. PLA anaerobic degradation increased by 97 % (from 395 to 779 NL biogas kgVS-1) and it was related to the acclimatization of known PLA-degraders such as Tepidimicrobium , Methanothermobacter and Tepidanaerobacter. Microbial acclimatization appears a suitable and low-cost strategy to enhance bioplastics circularity by promoting their anaerobic biodegradation and conversion into biogas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Direct oxidation of raw marine plants to FDCA would be a valuable technology. • Bioprocessing systems proposed for FDCA production have a high potential. • Biostrategies of the key enzymes could be used for improving depolymerization. • Macroalgae/seagrass could be useful feedstocks for bio-based chemical products. Marine plants, including macroalgae and seagrass, show promise as biorenewable feedstocks for sustainable chemical manufacturing. This study explores their potential in producing 2,5-furandicarboxylic acid (FDCA), a versatile platform chemical for commodity polymers. FDCA-based polyethylene 2,5-furandicarboxylate offers a sustainable alternative to petroleum-derived polyethylene terephthalate, commonly used in plastic bottles. Our research pioneers the concept of a marine plant-based FDCA biorefinery, introducing innovative approaches for sustainability and cost-effectiveness. This review outlines the use of ionic liquid-based solvents (ILS) and deep eutectic solvent (DES) systems in FDCA production. Additionally, we propose biomodification strategies involving target enzyme-encoding genes to enhance the depolymerization of non-structural storage glucans in marine plants. Our findings pave the way for eco-friendly biorefineries and biorenewable plastics. [ABSTRACT FROM AUTHOR]

[Display omitted] • The biomass reached 21.3 g DCW/L through high-density cell cultivation. • Cell culture and PHB accumulation were successfully conducted in one-step cultivation. • An 8.9 g/L PHBV copolymer with a 28.4 % 3HV molar fraction was successfully synthesized. • The physicochemical properties of the PHBV copolymer film were analyzed. The production of polyhydroxyalkanoates (PHAs) through the biological conversion of methane is a promising solution to address both methane emissions and plastic waste. Type II methanotrophs naturally accumulate a representative PHA, poly(3-hydroxybutyrate) (PHB), using methane as the sole carbon source. In this study, we aimed to produce poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV copolymer) with improved properties compared with PHB, using the type II methanotroph, Methylocystis sp. MJC1. We optimized the pH, valerate concentration, and valerate supply time in a one-step cultivation process using a gas bioreactor to enhance PHBV copolymer production yield and the 3-hydroxyvalerate (3HV) molar fraction. Under the optimal conditions, the biomass reached 21.3 g DCW/L, and PHBV copolymer accumulation accounted for 41.9 % of the dried cell weight, with a 3HV molar fraction of 28.4 %. The physicochemical properties of the purified PHBV copolymer were characterized using NMR, FTIR, TGA, DSC, and GPC. [ABSTRACT FROM AUTHOR]

[Display omitted] • A biobased, biodegradable, eco-friendly PLA/LA x carbon source was prepared. • High-molecular-weight PLA biodegraded better with slight ʟ-lactide. • Phylum unclassified_f__Rhodocyclaceae played a crucial role in denitrification. • Enriched Bacteroidota and Chloroflexi endow more biodegradability for PLA. • Mechanism of incorporating slight ʟ-lactide on PLA biodegradability was revealed. The utilization of wasted Poly(lactic acid) (PLA) as low-cost carbon sources in solid-phase denitrification is hindered by its low biodegradability, which can be attributed to its high molecular weight. This study presents a new approach by blending high-molecular-weight PLA with a small amount of ʟ-lactide (PLA/LA x) to treat nitrate-contaminated wastewater. The addition of ʟ-lactide enhanced the release of carbon from high-molecular-weight PLA. An impressive denitrification efficiency of 96.7% was achieved, accompanied by extremely low levels of accumulated NO 2 - - N (0.1 mg/L) and NH 4 + - N (0.4 mg/L). The quantity of ʟ-lactide used significantly impacted the bacterial community structure. A high abundance of the phyla Bacteroidota and Chloroflexi associated with polymer degradation was observed. The most dominant denitrifier was the genus unclassified_f__Rhodocyclaceae belonged to the phylum Proteobacteria. This study demonstrates that blending PLA with just 5 wt% lactide can transform it into a highly effective solid-phase carbon source to eliminate nitrates. [ABSTRACT FROM AUTHOR]

[Display omitted] • 13C from PBAT monomers was tracked under anaerobic and thermophilic conditions. • 1,4-butanediol and adipic acid were assimilated in the biomass. • 3 genera were able to directly metabolise at least 1 of the 3 PBAT monomer units. • A HQ-MAG was identified as A. thermophila and as an active degrader of butanediol. PBAT (poly butylene adipate-co-terephthalate) is a widely used biodegradable plastic, but the knowledge about its metabolization in anaerobic environments is very limited. In this study, the anaerobic digester sludge from a municipal wastewater treatment plant was used as inoculum to investigate the biodegradability of PBAT monomers in thermophilic conditions. The research employs a combination of 13C-labelled monomers and proteogenomics to track the labelled carbon and identify the microorganisms involved. A total of 122 labelled peptides of interest were identified for adipic acid (AA) and 1,4-butanedio (BD). Through the time-dependent isotopic enrichment and isotopic profile distributions, Bacteroides , Ichthyobacterium , and Methanosarcina were proven to be directly involved in the metabolization of at least one monomer. This study provides a first insight into the identity and genomic potential of microorganisms responsible for biodegradability of PBAT monomers during anaerobic digestion under thermophilic conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ralstonia eutropha 5119 can co-metabolize biomass derived byproducts with glucose. • Furfural, hydroxymethylfurfural and acetate promote biomass and PHA production. • Vanillin is more toxic followed by furfural > hydroxymethylfurfural > acetate. • Miscanthus biomass hydrolysate resulted in high PHA (Y p/s, 0.14 g/g) yield. • PHA produced from biomass hydrolysate has similar properties to P(3HB- co -3HV). Abstract Pretreatment of lignocellulosic biomass results in the formation of byproducts (furfural, hydroxymethylfurfural [HMF], vanillin, acetate etc.), which affect microbial growth and productivity. Furfural (0.02%), HMF (0.04%), and acetate (0.6%) showed positive effects on Ralstonia eutropha 5119 growth and polyhydroxyalkanoate (PHA) production, while vanillin exhibited negative effects. Response optimization and interaction studies between the variables glucose, ammonium chloride, furfural, HMF, and acetate using the response surface methodology resulted in maximum PHA production (2.1 g/L) at optimal variable values of 15.3 g/L, 0.43 g/L, 0.04 g/L, 0.05 g/L, and 2.34 g/L, respectively. Different lignocellulosic biomass hydrolysates (LBHs), including barley biomass hydrolysate (BBH), Miscanthus biomass hydrolysate (MBH), and pine biomass hydrolysate (PBH), were evaluated as potential carbon sources for R. eutropha 5119 and resulted in 1.8, 2.0, and 1.7 g/L PHA production, respectively. MBH proved the best carbon source, resulted in higher biomass (Y x/s, 0.31 g/g) and PHA (Y p/s, 0.14 g/g) yield. [ABSTRACT FROM AUTHOR]

The ability of cyanobacterium Arthrospira sp. to assimilate waste nitrogen sources (ammonium and urea) makes it an important candidate for wastewater management. The aim of this work was to evaluate a cultivation approach based on continuous-transitional-feeding regime (nitrate-ammonium-nitrate) in a photobioreactor to assess the effects of ammonium salts on Arthrospira sp. PCC 8005 metabolism. Using a comprehensive biochemical, proteomic and stoichiometric profiling of biomass, this study demonstrated that the proposed cultivation approach could increase the proteins and pigments yields by 20–30%, compared to the respective yields obtained from wild-type Arthrospira sp. strain A light-energy-transfer model was used to predict the biomass and oxygen productivities of Arthrospira sp. cultivated under transitional-feeding regime. 95 ± 2% match was observed between the experimental and simulated productivities. This study thus opened new avenues for use of ammonium rich wastewater for commercial production of high value pigments, biofuel and bioplastics using Arthrospira sp. [ABSTRACT FROM AUTHOR]

Photosynthetic Poly-β-hydroxybutyrate (PHB) productivity in cyanobacteria needs to be increased to make cyanobacterial derived bioplastics economically feasible and competitive with petroleum-based plastics. In this study, high PHB yielding mutants of Synechocystis sp. PCC 6714 have been generated by random mutagenesis, using UV light as a mutagen. The selection of strains was based on PHB content induced by nitrogen and phosphorus starvation. The fast growing mutant MT_a24 exhibited more than 2.5-fold higher PHB productivity than that of the wild-type, attaining values of 37 ± 4% dry cell weight PHB. The MT_a24 was characterized for phenotypes, CO 2 uptake rate and gene expression levels using quantitative PCR. Genome sequencing showed that UV mutagenesis treatment resulted in a point mutation in the ABC-transport complex, phosphate-specific transport system integral membrane protein A (PstA). The MT_a24 shows potential for industrial production of PHB and also for carbon capture from the atmosphere or point sources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrasonic-assisted hypochlorite activation effectively enhanced VFAs yield. • Solubilization and hydrolysis steps were improved by synergetic pretreatment. • The content and bioavailability of organic substrates were remarkably enhanced. • The functional anaerobes (e.g., Proteiniclasticum and Fonticella) were enriched. • The microbial metabolic activities for VFAs biosynthesis were up-regulated. The effective disruption of extracellular polymeric substances using appropriate pretreatment is critical to achieving resource recovery from sewage sludge (SS) by anaerobic fermentation. This work proposed an ultrasonic-assisted hypochlorite activation strategy for enhanced production of volatile fatty acids (VFAs) during SS fermentation. The results demonstrated that after individual ultrasonic and hypochlorite pretreatment, the maximum VFAs yield improved by 8 and 107% with that in control, respectively, while a combination of both techniques led to an improvement of 119%, indicating their synergistic effects on SS fermentation. This method enhanced the solubilization and hydrolysis efficiencies and contributed to the increased biodegradable substrates, which would be beneficial in enhancing microbial activity for VFAs production. The functional anaerobes, metabolic pathways, and gene expressions involved in VFAs biosynthesis were effectively improved. This work would bring a novel insight into the disposal of municipal solid waste for resource recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • InaKN-mediated E. coli surface display strategy produced novel cold-active PsLAC. • Display system had excellent efficiency of 88.0% and expression level of 29.6 U/mg. • Engineered bacteria had well capacity in activity recovery and maintenance at 15 °C. • PsLAC manufacture engineering efficiently degraded 48.0% of PE within 48 h at 15 °C. To eliminate efficiency restriction of polyethylene microplastics low-temperature biodegradation, a novel InaKN-mediated Escherichia coli surface display platform for cold-active degrading laccase PsLAC production was developed. Display efficiency of 88.0% for engineering bacteria BL21/pET-InaKN-PsLAC was verified via subcellular extraction and protease accessibility, exhibiting an activity load of 29.6 U/mg. Cell growth and membrane integrity revealed BL21/pET-InaKN-PsLAC maintained stable growth and intact membrane structure during the display process. The favorable applicability was confirmed, with 50.0% activity remaining in 4 days at 15 °C, and 39.0% activity recovery retention after 15 batches of activity substrate oxidation reactions. Moreover, BL21/pET-InaKN-PsLAC possessed high polyethylene low-temperature depolymerizing capacity. Bioremediation experiments proved that the degradation rate was 48.0% within 48 h at 15 °C, and reached 66.0% after 144 h. Collectively, cold-active PsLAC functional surface display technology and its significant contributions to polyethylene microplastics low-temperature degradation constitute an effective improvement strategy for biomanufacturing and microplastics cold remediation. [ABSTRACT FROM AUTHOR]

In the current study, the feasibility of utilizing municipal secondary wastewater sludge for Polyhydroxyalkanoate (PHA) extraction was improved by optimization of various parameters (temperature, duration and concentration of sludge solids). Optimized process parameters resulted in PHA recovery of 0.605 g, significantly higher than un-optimized conditions. The characterization of PHA was carried out by GC–MS, FT-IR and NMR ( 1 H and 13 C) spectroscopy. The PHA profile was found to be dominated by mcl PHA (58%) along with other diverse PHA. The results of the present study show rich diversity of PHA extracted from a raw material which is readily available at minimal cost. In conclusion, exploring the potential of wastes for production of bioplastics not only reduces the cost of bioplastic production, but also provides a sustainable means for waste management. [ABSTRACT FROM AUTHOR]

A microbial production process was developed to convert CO 2 and valeric acid into tailored poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) bioplastics. The aim was to understand microbial PHBV production in mixotrophic conditions and to control the monomer distribution in the polymer. Continuous sparging of CO 2 with pulse and pH-stat feeding of valeric acid were evaluated to produce PHBV copolyesters with predefined properties. The desired random monomer distribution was obtained by limiting the valeric acid concentration (below 1  g L - 1 ). 1 H-NMR, 13 C-NMR and chromatographic analysis of the PHBV copolymer confirmed both the monomer distribution and the 3-hydroxyvalerate (3HV) fraction in the produced PHBV. A physical-based model was developed for mixotrophic PHBV production, which was calibrated and validated with independent experimental datasets. To produce PHBV with a predefined 3HV fraction, an operating diagram was constructed. This tool was able to predict the 3HV fraction with a very good accuracy (2% deviation). [ABSTRACT FROM AUTHOR]

Kinetic models of anaerobic digestion (AD) are widely applied to soluble and particulate substrates, but have not been systematically evaluated for bioplastics. Here, five models are evaluated to determine their suitability for modeling of anaerobic biodegradation of the bioplastic poly(hydroxybutyrate- co -hydroxyvalerate) (PHBV): (1) first-order kinetics with and without a lag phase, (2) two-step first-order, (3) Monod (4) Contois, and (5) Gompertz. Three models that couple biomass growth with substrate hydrolysis (Monod, Contois, and Gompertz) gave the best overall fits for the data ( R 2 > 0.98 ) , with reasonable estimates of ultimate CH 4 production. The particle size limits of these models were then evaluated. Below a particle size of 0.8 mm, rates of hydrolysis and acetogenesis exceeded rates of methanogenesis with accumulation of intermediates leading to a temporary inhibition of CH 4 production. Based on model fit and simplicity, the Gompertz model is recommended for applications in which particle size is greater than 0.8 mm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimization steps increased by 85% the attained PHB production. • High PHB accumulation (70 %), production (14 g.L−1) and productivity (0.197 g.Lh−1). • Recovered biopolymer with high purity (>99 %). • Generation of a corn biorefinery system producing biofuels and PHB opportunity. The high costs of bioplastics' production may hinder their commercialization. Development of new processes with high yields and in biorefineries can enhance diffusion of these materials. This work evaluated the production of polyhydroxybutyrate (PHB) from the combination of milled corn starchy fraction hydrolysate and crude glycerol as substrates by the strain Cupriavidus necator LPB 1421. After optimization steps, maximum accumulation of 62 % of PHB was obtained, which represents 11.64 g.L−1 and productivity of 0.162 g.Lh−1. In a stirred tank bioreactor system with 8 L of operational volume, 70 % of PHB accumulation was reported, representing 14.17 g.L−1 of the biopolymer with 0.197 g.Lh−1 productivity. PHB recovery was conducted using a chemical digestion method, reaching >99 % purity. Therefore, the potential application of milled corn as substrate for PHB production was confirmed. The developed bioplastic process could be coupled to a bioethanol producing unit creating the opportunity of a sustainable and economic biorefinery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anaerobic co-digestion of PLA or PHB plastics with biowastes is feasible at pilot scale. • At an OLR of 2.5 g vS L-1 d-1, the reactor only fed with biowaste was not stable. • Addition of biodegradable plastics resulted in a more stable process. • PLA or PHB in the biogas plant feeding, did not affect the digestate quality. The development of selective biowaste collection in most European countries provides new opportunities for the anaerobic digestion sector. In parallel, extensive development of biodegradable plastics like polylactic-acid (PLA) and polyhydroxybutyrate (PHB), which facilitates the replacement of conventional plastics, has taken place in the past decade. This study investigated anaerobic co-digestion in semi-continuous reactors of biowastes (75 % Volatil Solids) and biodegradable plastics (25 % Volatil Solids, PLA and PHB). PHB was estimated to be fully biodegraded in the reactors. By contrast, PLA accumulated in the reactor, and an average biodegradation of 47.6 ± 17.9 % was estimated during the third hydraulic retention time. Pretreatment of PLA, by thermo-alkaline hydrolysis at 70 °C, with 2.5 w/v of Ca(OH) 2 for 48 h, improved the biodegradation yield of PLA to 77.5 ± 9.3 %. Finally, it was highlighted that PLA or PHB addition to the feed did not further affect the agronomic properties of the digestate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pseudohalocynthiibacter aestuariivivens P96 is a novel producer of P(3HB) polymer. • Genome analysis revealed the presence of genes involved in the PHB biosynthesis. • SEM and TEM analysis clearly showed granule accumulation in the productive medium. • The P(3HB) production is 4.73 g/L and the intracellular content 87 % dcw. • P. aestuariivivens P96 displayed high industrial potential. The production and disposal of plastics from limited fossil reserves, has prompted research for greener and sustainable alternatives. Polyhydroxyalkanoates (PHAs) are biocompatible, biodegradable, and thermoprocessable polyester produced by microbes. PHAs found several applications but their use is limited due to high production cost and low yields. Herein, for the first time, the isolation and characterization of Pseudohalocynthiibacter aestuariivivens P96, a marine bacterium able to produce surprising amount of PHAs is reported. In the best growth condition P96 was able to reach a maximum production of 4.73 g/L, corresponding to the 87 % of total cell dry-weight. Using scanning and transmission microscopy, lab-scale fermentation, spectroscopic techniques, and genome analysis, the production of thermoprocessable polymer Polyhydroxybutyrate P(3HB), a PHAs class, endowed with mechanical and thermal properties comparable to that of petroleum-based plastics was confirmed. This study represents a milestone toward the use of this unexplored marine bacterium for P(3HB) production. [ABSTRACT FROM AUTHOR]

[Display omitted] • The selection of waste stream for synthesis of biopolymer is an important task. • Recycling of waste stream for biopolymer production reduces several ecological risks. • Processing of green plastic from different waste stream is possible. • Environmental sustainability and its impact on biopolymer production is reviewed. • The emission of greenhouse gas and non-renewable energy use is index of lifecycle assessment. Polyhydroxyalkanoates (PHA) are the more attractive sustainable green plastic, and it has the potential to replace petroleum-based plastics (PBP) in the global market. Recently, most of the developed and developing countries have banned the use of traditional PBP. This increases the demand for green plastic production and positively impacts the global market. Producing green plastic from various waste streams such as whey, animal, and crude glycerol will be eco-friendly and cost-effective. However, the factors influencing the environmental sustainability of PHA production from different waste streams are still unclear. This review could be reinforced concrete to researchers to gather deep knowledge on techno-economic analysis, life-cycle assessment, environmental and ecological risks caused during PHA production from different waste streams. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyhydroxyalkanoate (PHA) is a promising alternative to petrochemical-based plastics. • The incorporation of monomers such as 3HP, 3HHx, 4HV, 4HB, 5HV, and 6HHx in P(3HB) shows amorphous and elastomer properties. • Lignocellulosic biomass, Levulinic acid, Glycerol and Waste oil can be utilized as feedstocks for sustainable and inexpensive PHA production. • Metabolic engineering can contribute to the expansion of the PHA portfolio from renewable resources. Petrochemical-based plastics cause environmental pollution and threaten humans and ecosystems. Polyhydroxyalkanoate (PHA) is considered a promising alternative to nondegradable plastics since it is eco-friendly and biodegradable polymer having similar properties to conventional plastics. PHA's material properties are generally determined by composition and type of monomers in PHA. PHA can be designed in tailor-made manner for their suitable application areas. Among many monomers in PHAs, ω-hydroxalkanoates such as 3-hydroxypropionate (3HP), 4-hydroxybutyrate (4HB), 5-hydroxyvalerate (5HV), and 6-hydroxyhexanoate (6HHx) and medium-chain-length 3-hydroxyalkanoate such as 3-hydroxyhexanoate (3HHx) and 4-hydroxyvalerate (4HV), have been examined as potential monomers able to confer amorphous and elastomer properties when these are incorporated as comonomer in poly(3-hydroxybutyrate) copolymer that has 3HB as main monomer along with comonomers in different monomer fraction. Herein, recent advances in production of PHAs designed to have amorphous and elastomeric properties from renewable sources such as lignocellulose, levulinic acid, crude glycerol, and waste oil are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Semi-automated fabrication system for an easy-to-scale-up photobioreactor (PBR). • Baffle and sparger operating conditions were optimized to maximize mass transfer. • Areal biomass yield was improved by 21% compared to the existing PBR. • The polyhydroxybutyrate (PHB) content of the produced biomass was 29% higher. • Scale-up to 2-ton PBR without cultivation performance deterioration. Photosynthetic polyhydroxybutyrate (PHB) production is an attractive technology for realizing a sustainable society by simultaneously producing useful biodegradable plastics and mitigating CO 2. It is necessary to establish an economical large-scale photobioreactor (PBR) capable of effectively cultivating photosynthetic microorganisms such as cyanobacteria. A roll-to-roll winding machine/heat-sealer hybrid system for fabricating an easy-to-scale-up PBR was developed in the present study. The baffle design was optimized to facilitate mass transfer within the PBR, and the operating conditions of the gas sparger were investigated to maximize the CO 2 transfer efficiency. The newly developed PBR was able to produce biomass of PHB content 10.7 w/w% at a rate of 6.861 g m−2 d−1, 21 % improved biomass productivity compared with the existing PBR. It was confirmed that biomass productivity was maintained even when PBR was scaled up to 2 tons. Consequently, the newly developed PBR is expected to improve the feasibility of photosynthetic PHB production. [ABSTRACT FROM AUTHOR]

• Utilization of agroresidues for poly-3-hydroxy alkanoates (PHA) production were discussed. • Challenges in PHA production and future perspectives were addressed. • Discussed strategies adopted for preetreatment of agroresidues. • Blending with different biopolymers improved properties of the PHA composite. The enormous production and widespread applications of non -biodegradable plastics lead to their accumulation and toxicity to animals and humans. The issue can be addressed by the development of eco-friendly strategies for the production of biopolymers by utilization of waste residues like agro residues. This will address two societal issues – waste management and the development of an eco-friendly biopolymer, poly-3-hydroxy alkanoates (PHAs). Strategies adopted for utilization of agro-residues, challenges and future perspectives are discussed in detail in this comprehensive review. The possibility of PHA properties improvements can be increased by preparation of blends. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phaffia rhodozyma was evaluated as a potential source of bioproducts. • Recovery and fractionation of astaxanthin, β-carotene, proteins and lipids. • Integration of a sequential operations in a biorefinery approach. • Carotenoids to produce sustainable bioactive plastics. Carotenoids over-producing yeast has become a focus of interest of the biorefineries, in which the integration of the bioproduction with the following downstream processing units for the recovery and purification of carotenoids and other value-added byproducts is crucial to improve the sustainability and profitability of the overall bioprocess. Aiming the future implementation of Phaffia rhodozyma -based biorefineries, in this work, an integrative process for fractionation of intracellular compounds from P. rhodozyma biomass using non-hazardous bio-based solvents was developed. After one-extraction step, the total amount of astaxanthin, β-carotene, lipids and proteins recovered was 63.11 µg/g DCW , 42.81 µg/g DCW , 53.75 mg/g DCW and 10.93 mg/g, respectively. The implementation of sequential back-extraction processes and integration with saponification and precipitation operations allowed the efficient fractionation and recovery (% w/w) of astaxanthin (∼72.5 %), β-carotene ∼90.17 %), proteins (21.04 %) and lipids (23.72 %). After fractionation, the manufacture of carotenoids-based products was demonstrated, through the mixture of carotenoids-rich extracts with bacterial cellulose to obtain biologically active bioplastics. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study assessed the feasibility of producing VFAs from 5 commercial bioplastics. • Acidogenic fermentation of PHA by non-pretreated anaerobic sludge was achieved. • PCL, PLA and PBS did not support VFA production via microbial fermentation. • PHB and PHBV were selectively bioconverted towards acetate and butyrate. • First systematic validation of PHAs to VFAs as precursors of high-value products. The feasibility of producing volatile fatty acids (VFAs) from five commercial bioplastics via acidogenic fermentation by a non-pretreated anaerobic sludge was investigated. Mesophilic, anaerobic, acidogenic batch assays at 1, 10 and 20 g/L feed concentrations revealed the feasibility of producing VFAs from polyhydroxyalkanoates (PHA), i.e., PHB and PHBV, but not from PBS, PCL and PLA under the test conditions and time. However, only high PHA substrate concentrations (10–20 g/L) resulted in organic overloading and decreasing the pH of the culture broth down to 4–5, which in turn induced the accumulation of VFAs via kinetic imbalance between acidogenesis and methanogenesis. Gaseous carbon (C-CO 2 and C-CH 4) accounted for 8–35% of the total initial carbon, while C-VFAs represented 10–18%, mainly as acetate and butyrate. This study represents the first systematically assessed proof-of-concept to produce VFAs from PHA, which is key for the design of bioplastic-to-bioplastic recycling (bio)technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • State-of-the-art PPW valorization is comprehensively reviewed. • Bioconversion of PPW into ethanol, butanol, hydrogen, and biogas is discussed. • Thermochemical conversions of PPW are presented and thoroughly discussed. • The review covers the physical, chemical, and physicochemical pretreatment of PPW. • The review encompasses the key challenges associated with PPW-based biorefinery. Potato is the fourth most abundant crop harvested annually worldwide. Potato peel waste (PPW) is the main waste stream of potato-processing industries which is generated in large quantities and is a threat to the environment globally. However, owing to its compositional characteristics, availability, and zero cost, PPW is a renewable resource for the production of high-value bioproducts. Hence, this study provides a state-of-the-art overview of advancements in PPW valorization through biological and thermochemical conversions. PPW has a high potential for biofuel and biochemical generation through detoxification, pretreatment, hydrolysis, and fermentation. Moreover, many other valuable chemicals, including bio-oil, biochar, and biosorbents, can be produced via thermochemical conversions. However, several challenges are associated with the biological and thermochemical processing of PPW. The insights provided in this review pave the way toward a PPW-based biorefinery development, providing sustainable alternatives to fossil-based products and mitigating environmental concerns. [ABSTRACT FROM AUTHOR]

Two-stage screening procedure isolated the ligninolytic bacteria with good bioplastic accumulation capacity, which exhibited the great potential to improve lignin valorization. [Display omitted] • A two-stage screening procedure is designed to identify four ligninolytic bacteria. • The isolated bacteria exhibit good ligninolytic performance of alkaline lignin. • The isolated bacteria show high accumulation capacity of polyhydroxyalkanoates. • Fed-batch mode facilitates the bioconversion of aromatics to polyhydroxyalkanoates. • The isolated bacteria are the promising host strains of microbial lignin valorization. Biological valorization of lignin to bioplastics is a promising route to improve biorefinery efficiency and address environmental challenges. A two-stage screening procedure had been designed to successfully identify four ligninolytic bacteria from soil samples. The isolated bacteria displayed substrate preference of guaiacyl- and hydroxyphenyl-based aromatics, but they effectively synthesized polyhydroxyalkanoates (PHAs). B. cepacia B1-2 and P. putida KT3-1 accumulated 27.3% and 20.9% PHA in cells and achieved a titer of 280.9 and 204.1 mg/L, respectively, from p -hydroxybenzoic acid. The isolated bacteria exhibited good ligninolytic performance indicated by the degradation of β -O-4 linkage and small molecules. B. cepacia B1-2 grew well on actual lignin substrate and yielded a PHA titer of 87.2 mg/L. With the design of fed-batch mode, B. cepacia B1-2 produced the highest PHA titer of 1420 mg/L from lignin-derived aromatics. Overall, isolated ligninolytic bacteria show good PHA accumulation capacity, which are the promising host strains for lignin valorization. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHA) production was evaluated in a multistage operation using food waste as a renewable feedstock. The first step involved the production of bio-hydrogen (bio-H 2 ) via acidogenic fermentation. Volatile fatty acid (VFA) rich effluent from bio-H 2 reactor was subsequently used for PHA production, which was carried out in two stages, Stage II (culture enrichment) and Stage III (PHA production). PHA-storing microorganisms were enriched in a sequencing batch reactor (SBR), operated at two different cycle lengths (CL-24; CL-12). Higher polymer recovery as well as VFA removal was achieved in CL-12 operation both in Stage II (16.3% dry cell weight (DCW); VFA removal, 84%) and Stage III (23.7% DCW; VFA removal, 88%). The PHA obtained was a co-polymer [P(3HB-co-3HV)] of PHB and PHV. The results obtained indicate that this integrated multistage process offers new opportunities to further leverage large scale PHA production with simultaneous waste remediation in the framework of biorefinery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Full-scale assessment of bioplastics' anaerobic degradation. • Starch-based and polylactic acid-based bioplastics degrade differently during AD. • AD of polylactid acid-based items produce large amount of biomethane. • Bioplastics' AD can reduce their leakage into natural environments. • Starch-based shoppers may be degraded by coupled AD and composting. The aim of the present study was to evaluate the anaerobic degradability and the potential recovery of biomethane from different bioplastics using a full-scale approach. Bioplastics were placed inside a real anaerobic digestion plant working under thermophilic conditions and quantitative and qualitative degradation of bioplastics was evaluated. Laboratory-scale experiments were used to determine the amount of biomethane produced by anaerobic degradation of bioplastics. Polylactic acid-based items may degrade completely using retention times compatible with anaerobic digestion plants contributing positively to biomethane production, i.e., in 90 days 397 ± 8 NL CH 4 kg volatile solids -1 were produced by polylactic acid-based cutlery. Starch-based shoppers showed a quick degradation of the starch component in the first month of anaerobic digestion, followed by a slow degradation of the polyester component. Anaerobic digestion and/or anaerobic digestion coupled to digestate composting may represent the best strategy to dispose these wastes meeting the principles of Circular Economy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compostable certified bioplastics were not compatible with the bio-waste treatment. • Bioplastics' residues < 2 mm were found in the final composts. • Polylactic acid lowered compost pH and negatively affected the germination index. • Further research on the effect of starch-based bioplastics on earthworms is needed. • Compost from bio-waste treatment may be a source of environmental contamination. Bioplastics may be collected in the bio-waste treatment, which is often composed of anaerobic digestion and subsequent aerobic composting of the digestates. The aim of this study was to evaluate the degradability of polylactic acid (PLA) and starch-based bioplastics (SBB) spoons under industrial conditions. Biomethane potential (BMP) was measured and biogas production was monitored, while the quality of composts was assessed by phytotoxicity and ecotoxicity tests. The bioplastics disintegration resulted in 65.1 ± 4.6 % for PLA and ≤ 65.0 ± 7.4 % for SBB, not achieving the target set by UNI EN 13,432 standard, and several residues were found in compost. Phytotoxicity tests on seeds reported the lowest Germination Index for PLA elutriate, whereas a potential negative effect of SBB on soil fauna was detected. Further investigation is needed to assess the fate of these ever-growing materials under industrial conditions, and also evaluate the effects of residues in compost. [ABSTRACT FROM AUTHOR]

[Display omitted] • Black liquor is a prospective lignocellulosic feedstock for circular bioeconomy. • Black liquor can be converted into bioplastics, chemicals, hydrogen and methane. • Anaerobic digestion would be the keystone process in black liquor valorization. • Policy related research is required in the sustainable fuel production. Lignocellulosic biomass is projected as a prospective renewable alternative to petroleum for the production of fuel and chemicals. Pretreatment is necessary to disrupt the lignocellulosic structure for extraction of cellulose. Biomass after pretreatment is segregated into cellulose rich solid fraction and black liquor (lignin and hemicelluloses) as a liquid stream. The plant polysaccharide-based industry primarily utilizes the cellulosic fraction as raw material, and carbon rich black liquor discarded as waste or burnt for energy recovery. This review highlights the recent advancements in the biological and chemical valorization of black liquor into fuels and chemicals. The recent research attempted for bioconversion of black liquor into Bioplastic, Biohydrogen, Biogas, and chemicals has been discussed. In addition, the efforts to replace the conventional energy recovery method with the advanced chemical process along with their modifications have been reviewed that will decide the sustainability of the lignocellulosic biomass-based industry. [ABSTRACT FROM AUTHOR]

This work describes the production of polyhydroxyalkanoates (PHAs) as a side stream process on a municipal waste water treatment plant (WWTP) at different operation conditions. Therefore various tests were conducted regarding a high PHA production and stable PHA composition. Influence of substrate concentration, temperature, pH and cycle time of an installed feast/famine-regime were investigated. The results demonstrated a strong influence of the operating conditions on the PHA production. Lower substrate concentration, 20 °C, neutral pH-value and a 24 h cycle time are preferable for high PHA production up to 28.4% of cell dry weight (CDW). PHA composition was influenced by cycle time only and a stable PHA composition was reached. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pseudomonas genus is a potent microbe in degrading polyethylene. • The crystalline nature of Polyethylene terephthalate makes it difficult for microbial degradation. • Ideonella sakaiensis has a remarkable role in PET degradation. • Polystyrene is a hydrophobic thermoplastic which makes it difficult to hydrolyse. • Starch grafted polystyrene is more prone to biodegradation. Plastics are a kind of utility product that has become part and parcel of one's life. Their continuous usage, accumulation, and contamination of soil and water pose a severe threat to the biotic and abiotic components of the environment. It not only increases the carbon footprints but also contributes to global warming. This calls for an urgent need to develop novel strategies for the efficient degradation of plastics. The microbial strains equipped with the potential of degrading plastic materials, which can further be converted into usable products, are blessings for the ecosystem. This review comprehensively summarizes the microbial technologies to degrade different plastic types, such as polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP), and polyurethane (PU). The study also describes the utilization of degraded plastic material as feedstock for its conversion into high-value chemicals. [ABSTRACT FROM AUTHOR]

• The kinetics of bioplastics biodegradation have not been dealt with in depth. • 9 out of 26 analyzed NLRs, were proper for monitoring the AD of bioplastics. • M9 selected as the best NLR owing to the simplicity and good statistical criteria. • MLP-ANN had an agreement in enough depth to data and picked as the superior model. Bioplastic biodegradation showed varying behavior during the process of biodegradation. The First-order and Gompertz models are the most prevalent models for monitoring biodegradation in an anaerobic digestion (AD) process, which do not suit adequately bioplastics fermentation modeling. This research aimed at studying the kinetics of methane production during AD of starch-based bioplastic by using a large library of non-linear regressions (NLRs) and an artificial neural network (ANN). Although 26 NLR models (25 were outlined in the AD literature + 1 modified by authors) have been analyzed, 9 of them were proper predictors for the whole AD process for methane production. In the end M9, which has been proposed by authors, was selected owing to the simplicity of regression as well as good statistical criteria. Moreover, MLP-ANN could outperform the NLR model and has been selected as the superior model that can define the kinetics of bioplastic AD. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sugar beet pulp is a sustainable lignocellulosic source for pectin based compounds. • Super- and subcritical water hydrolysis can improve reducing sugar yield. • Value added chemicals and products can be derived from sugar beet pulp hydrolysis. • Biorefinery setup in combination with power and heat generation is possible. The processing of sugar beet in the sugar production industry releases huge amounts of sugar beet pulp as waste which can be considered a valuable by-product as a source of cellulose, hemicellulose, and pectin. Valorization of sugar beet pulp into value added products occurs through acid hydrolysis, hydrothermal techniques, and enzymatic hydrolysis. Biochemical conversion of beet pulp into simple fermentable sugars for producing value added products occurs through enzymatic hydrolysis is a cost effective and eco-friendly process. While beet pulp has predominantly been used as a fodder for livestock, recent developments in its biotechnological valorization have unlocked its value as a feedstock in the production of biofuels, biohydrogen, biodegradable plastics, and platform chemicals such as lactic acid, citric acid, alcohols, microbial enzymes, single cell proteins, and pectic oligosaccharides. This review brings forward recent biotechnological developments made in the valorization of sugar beet pulp into valuable products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bioplastics production using cheaper carbon source is crucial for cost reduction. • Various strategies to improve PHA production from C1 gases were accomplished. • Autotrophs, acetogens, and methanotrophs were optimized and engineered for PHA. • Process optimization and PHA copolymer production from C1 gases were carried out. • C1 refinery to bioplastics is prospective methodology to ease environmental issues. Biosynthesis of polyhydroxyalkanoates (PHAs) from C1 gases is highly desirable in solving problems such as climate change and microplastic pollution. PHAs are biopolymers synthesized in microbial cells and can be used as alternatives to petroleum-based plastics because of their biodegradability. Because 50% of the cost of PHA production is due to organic carbon sources and salts, the utilization of costless C1 gases as carbon sources is expected to be a promising approach for PHA production. In this review, strategies for PHA production using C1 gases through fermentation and metabolic engineering are discussed. In particular, autotrophs, acetogens, and methanotrophs are strains that can produce PHA from CO 2 , CO, and CH 4. In addition, integrated bioprocesses for the efficient utilization of C1 gases are introduced. Biorefinery processes from C1 gas into bioplastics are prospective strategies with promising potential and feasibility to alleviate environmental issues. [ABSTRACT FROM AUTHOR]

• Only PHAs were aerobically/anaerobically biodegradable under aqueous conditions. • PHB and PHBV yielded up to 496 and 480 Nm3 of CH 4 per ton, respectively. • C-balance analysis for the different carbon sinks estimates polymer biodegradability. • Mineralization rate depended on the total specific surface area of polymer. • The modified Gompertz model accurately described bioplastic biodegradation. The biodegradation of PHB, PHBV, PBS, PBAT, PCL, PLA, and a PLA-PCL blend was compared under aerobic and anaerobic aqueous conditions assessing biodegradation kinetics, extent, carbon fate and particle size influence (in the range of 100–1000 µm). Under standard test conditions, PHB and PBHV were biodegraded anaerobically (83.9 ± 1.3% and 81.2 ± 1.7%, respectively) in 77 days or aerobically (83.0 ± 1.6% and 87.4 ± 7.5%) in 117 days, while PCL was only biodegraded (77.6 ± 2.4%) aerobically in 177 days. Apparent biomass growth accounted for 10 to 30.5% of the total initial carbon depending on the bioplastic and condition. Maximum aerobic and anaerobic biodegradation rates were improved up to 331 and 405%, respectively, at the lowest particle size tested (100–250 µm). This study highlights the usefulness of analysing biodegradation kinetics and carbon fate to improve both the development and testing of biodegradable materials, and waste treatments in the context of a circular bioeconomy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lignocellulosic biomass as an alternative to glucose for bioplastic synthesis. • Aliphatic PLA and PHB are commercially available as bioplastics. • Aromatic biomonomers as starting materials for high-performance bioplastics. • Cost-effective technologies should be developed for biomonomer purification. • High thermal/mechanical performance of plastics from biomonomers. Lignocellulosic biomass has great potential as an inedible feedstock for bioplastic synthesis, although its use is still limited compared to current edible feedstocks of glucose and starch. This review focuses on recent advances in the production of biopolymers and biomonomers from lignocellulosic feedstocks with downstream processing and chemical polymer syntheses. In microbial production, four routes composed of existing poly (lactic acid) and polyhydroxyalkanoates (PHAs) and the emerging biomonomers of itaconic acid and aromatic compounds were presented to review present challenges and future perspectives, focusing on the use of lignocellulosic feedstocks. Recently, advances in purification technologies decreased the number of processes and their environmental burden. Additionally, the unique structures and high-performance of emerging lignocellulose-based bioplastics have expanded the possibilities for the use of bioplastics. The sequence of processes provides insight into the emerging technologies that are needed for the practical use of bioplastics made from lignocellulosic biomass. [ABSTRACT FROM AUTHOR]