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Industrial-scale upcycling of waste polyethylene terephthalate (PET) plastic into porous carbon globally for CO2 capture was verified as a multifunctional alternative to conventional CO2 absorption and plastic waste management technologies.

Microalgae-based antibiotic removal treatment has attracted attention because of its low carbon and sustainable advantages. The microalgal co-metabolism system with a suitable carbon source leads to enhanced performance of pollutant removal. However, currently, limited knowledge is available for the removal of fluoroquinolone using a microalgae-mediated co-metabolism system. In this study, we first investigated that the biotic processes by alga Haematococcus lacustris in the co-metabolism system by adding glycerol would be the main contributors responsible for the removal of 10 mg/L ofloxacin (OFL) with the efficiency of 79.73% and the removal of 10 mg/ L enrofloxacin (ENR) with the efficiency of 54.10%, respectively. Furthermore, we found that pyruvate from glycerol was converted into substrates and precursors, thereby resulting in the significant accumulations of microalgal astaxanthin and lipid. The astaxanthin content of H. lacustris was achieved at 4.81% and 4.69% treated with OFL and ENR in the presence of glycerol, with 16.04% and 14.55% of lipid content, respectively. The proposed metabolites and pathways were identified to plausibly explain the biodegradation of fluoroquinolone by H. lacustris. The molecular analyses demonstrated that cytochrome P450 (CYP450) enzymes are responsible for the biodegradation of fluoroquinolone, and it was further verified that fluoroquinolones might insert into CYP450 to finally form an efficient and tight binding conformation by molecular dynamic simulation. These findings provide a microalgae-based route for feasible and sustainable biodegradation of antibiotics using a co-metabolism strategy comprising glycerol as a carbon source, with the synergistic accumulation of valuable products., peer-reviewed

Synthetic microbial consortia show promising applications for fine chemical production, especially with long metabolic pathways. In this study, a synthetic microbial consortium consisting of

This study demonstrates the feasibility of establishing a natural compound supply chain in a biorefinery. The process starts with the biological or chemical hydrolysis of food and agricultural waste into simple and fermentative sugars, followed by their fermentation into more complex molecules. The yeast strain, Yarrowia lipolytica, was modified by introducing high membrane affinity variants of the carotenoid cleavage dioxygenase enzyme, PhCCD1, to increase the production of the aroma compound, β-ionone. The initial hydrolysis process converted food waste or sugarcane bagasse into nutrient-rich hydrolysates containing 78.4 g/L glucose and 8.3 g/L fructose, or 34.7 g/L glucose and 20.1 g/L xylose, respectively. During the next step, engineered Y. lipolytica strains were used to produce β-ionone from these feedstocks. The yeast strain YLBI3120, carrying a modified PhCCD1 gene was able to produce 4 g/L of β-ionone with a productivity of 13.9 mg/L/h from food waste hydrolysate. This is the highest yield reported for the fermentation of this compound to date. The integrated process described in this study could be scaled up to achieve economical large-scale conversion of inedible food and agricultural waste into valuable aroma compounds for a wide range of potential applications.

This study demonstrates the feasibility of establishing a natural compound supply chain in a biorefinery. The process starts with the biological or chemical hydrolysis of food and agricultural waste into simple and fermentative sugars, followed by their fermentation into more complex molecules. The yeast strain

Bread is Europe's most wasted food, and the second most wasted food after potatoes in UK. Bread waste (BW) is a clean source of high-quality fermentable sugars. In this study, the potential of Enterobacter ludwigii to accumulate 2,3-butanediol (BDO) from BW was evaluated. Initially, the optimal inoculum size and yeast extract concentration were determined, followed by extraction of sugars from BW using acid and enzymatic hydrolysis. A glucose yield of 330-530 g/kg BW was obtained, and the sugars released were utilised for BDO production by E. ludwigii. The fed-batch cultivation using pure glucose and glucose rich hydrolysates from acid and enzymatic hydrolysis resulted in BDO titres of 144.5, 135.4, and 138.8 g/L, after 96 h, with yield of 0.47, 0.42 and 0.48 g/g yield, respectively. The innovation of the work is valorisation of BW to BDO with a circular biorefining approach and thus, reducing BW disposal and associated environmental burden.

According to the US Department of Energy, succinic acid (SA) is a top platform chemical that can be produced from biomass. Bread waste, which has high starch content, is the second most wasted food in the UK and can serve as a potential low cost feedstock for the production of SA. This work evaluates the environmental performance of a proposed biorefinery concept for SA production by fermentation of waste bread using a cradle-to-factory gate life cycle assessment approach. The performance was assessed in terms of greenhouse gas (GHG) emissions and non-renewable energy use (NREU). Waste bread fermentation demonstrated a better environmental profile compared to the fossil-based system, however, GHG emissions were about 50% higher as compared to processes using other biomass feedstocks such as corn wet mill or sorghum grains. NREU for fermentative SA production using waste bread was significantly lower (~ 46%) than fossil-based system and about the same as that of established biomass-based processes, thus proving the great potential of waste bread as a valuable feedstock for bioproduction of useful chemicals. The results show that steam and heating oil used in the process were the biggest contributors to the NREU and GHG emissions. Sensitivity analyses highlighted the importance of the solid biomass waste generated in the process which can potentially be used as fish feed. The LCA analysis can be used for targeted optimization of SA production from bread waste, thereby enabling the utilization of an otherwise waste stream and leading to the establishment of a circular economy.

The current perspective presents an outlook on developing gut-like bioreactors with immobilized probiotic bacteria using cellulose hydrogels. The innovative concept of using hydrogels to simulate the human gut environment by generating and maintaining pH and oxygen gradients in the gut-like bioreactors is discussed. Fundamentally, this approach presents novel methods of production as well as delivery of multiple strains of probiotics using bioreactors. The relevant existing synthesis methods of cellulose hydrogels are discussed for producing porous hydrogels. Harvesting methods of multiple strains are discussed in the context of encapsulation of probiotic bacteria immobilized on cellulose hydrogels. Furthermore, we also discuss recent advances in using cellulose hydrogels for encapsulation of probiotic bacteria. This perspective also highlights the mechanism of probiotic protection by cellulose hydrogels. Such novel gut-like hydrogel bioreactors will have the potential to simulate the human gut ecosystem in the laboratory and stimulate new research on gut microbiota.

A wearable textile that is engineered to reflect incoming sunlight and allow the transmission of mid-infrared radiation simultaneously would have a great impact on the human body's thermal regulation in an outdoor environment. However, developing such a textile is a tough challenge. Using nanoparticle-doped polymer (zinc oxide and polyethylene) materials and electrospinning technology, we have developed a nanofabric with the desired optical properties and good applicability. The nanofabric offers a cool fibrous structure with outstanding solar reflectivity (91%) and mid-infrared transmissivity (81%). In an outdoor field test under exposure of direct sunlight, the nanofabric was demonstrated to reduce the simulated skin temperature by 9 °C when compared to skin covered by a cotton textile. A heat-transfer model is also established to numerically assess the cooling performance of the nanofabric as a function of various climate factors, including solar intensity, ambient air temperature, atmospheric emission, wind speed, and parasitic heat loss rate. The results indicate that the nanofabric can completely release the human body from unwanted heat stress in most conditions, providing an additional cooling effect as well as demonstrating worldwide feasibility. Even in some extreme conditions, the nanofabric can also reduce the human body's cooling demand compared with traditional cotton textile, proving this material as a feasible solution for better thermoregulation of the human body. The facile fabrication of such textiles paves the way for the mass adoption of energy-free personal cooling technology in daily life, which meets the growing demand for healthcare, climate change, and sustainability.

The unicellular freshwater green alga

Background Despite the great potential of marine diatoms in biofuel sector, commercially viable biofuel production from native diatom strain is impractical. Targeted engineering of TAG pathway represents a promising approach; however, recruitment of potential candidate has been regarded as critical. Here, we identified a glycerol-3-phosphate acyltransferase 2 (GPAT2) isoform and overexpressed in Phaeodactylum tricornutum. Results GPAT2 overexpression did not impair growth and photosynthesis. GPAT2 overexpression reduced carbohydrates and protein content, however, lipid content were significantly increased. Specifically, TAG content was notably increased by 2.9-fold than phospho- and glyco-lipids. GPAT2 overexpression elicited the push-and-pull strategy by increasing the abundance of substrates for the subsequent metabolic enzymes, thereby increased the expression of LPAAT and DGAT. Besides, GPAT2-mediated lipid overproduction coordinated the expression of NADPH biosynthetic genes. GPAT2 altered the fatty acid profile in TAGs with C16:0 as the predominant fatty acid moieties. We further investigated the impact of GPAT2 on conferring abiotic stress, which exhibited enhanced tolerance to hyposaline (70%) and chilling (10 ºC) conditions via altered fatty acid saturation level. Conclusions Collectively, our results exemplified the critical role of GPAT2 in hyperaccumulating TAGs with altered fatty acid profile, which in turn uphold resistance to abiotic stress conditions.

Bioenergy and biochemicals can be sustainably produced through fermentation and anaerobic digestion (AD). However, this bioconversion processes could be more economical if the hydrolysis rates of substrates in bioreactors can be accelerated. In this review, the feasibilities of including enzymatic hydrolysis (EH) in various bioconversion systems were studied to facilitate the biological synergy. The reaction kinetics of EH in bioconversion systems comparing pretreated lignocellulosic biomass (LCB) and food waste (FW) substrates were reviewed. Possible strategies to improve the hydrolysis efficiency were explored, including co-cultivation during enzyme production and replacement of pure enzyme with on-site produced fungal mash during EH. Key insights into improvement of current AD and fermentation technologies were summarized and further formed into suggestions of future directions in techno-economic feasibility of biorefinery using mixture of the first-generation food crop feedstock with FW; and/or co-digestion of FW with LCB.

Secondary/waste streams have previously been used as feedstocks to produce sophorolipids (SLs), a biosurfactant with low eco-toxicity and high biodegradability, in order to reduce production costs and protect the environment. However, limited productivities and titres from these feedstocks remain as important challenges. Thus, the optimisation of fermentation medium using bakery waste oil (BWO) as a hydrophobic carbon source by Starmerella bombicola was investigated. The optimal conditions were determined by multiple linear regression. Inoculum concentration of 2% v v-1 and BWO and glucose concentrations of 60 g L-1 and 100 g L-1, respectively, resulted in an increase of 19.6% in the lactonic SL (67.8 +/- 11.5 g L-1). Further optimisation revealed the profound influence of KOH in pH regulation, i.e., compared with NaOH, KOH led to higher concentrations of biomass (p < 0.05), more BWO consumption, and thus, an increase of 42.2% in SL titre (96.4 +/- 9.1 g L-1) and corresponding volumetric and specific productivities of 0.446 g L- 1h- 1 and 0.027 g g CDW- 1h- 1, respectively. Multiple regression analysis demonstrated that pH and the concentration of BWO as the feeding medium were the most influential parameters in fermentative SL production. This study demonstrated that KOH offered additional benefit to improve SLs titre by maintaining high biomass during the bioprocess, displayed the importance of intracellular potassium in cell viability and improved the valorisation of BWO process.

Soil acidification is the main cause for aggravation of soil cadmium (Cd) pollution. Biochar treatment can increase the soil pH and decrease the Cd availability in soils. However, there is limited information in literature on the comprehensive assessment of the response of Cd fractions to biochar. Therefore, in the present meta-analysis study, we evaluate the response of Cd fractions to biochar application in soils with different pH and to further examine the effect of physicochemical properties of biochar on Cd. Results from the overall analysis indicated that biochar treatment increased the soil pH by 7.0%, thereby decreasing the amount of available Cd (37.3%). In acidic soil, biochar significantly reduced the acid-soluble fraction (Acid-Cd) of Cd by 36.8%, while Oxidizable fraction of Cd (Oxid-Cd, 20.9%) and Residual fraction of Cd (Resid-Cd, 22.2%) were significantly increased. In neutral soils, only Acid-Cd was significantly reduced (33.0%) in the presence of biochar. In alkaline soils, biochar caused significant reduction in Acid-Cd of 12.4% and an increase in Oxid-Cd and Resid-Cd of 26.6% and 47.8%, respectively. Further, our findings showed that biochar with cation exchange capacity100 cmol

Dependency on plastic commodities has led to a recurrent increase in their global production every year. Conventionally, plastic products are derived from fossil fuels, leading to severe environmental concerns. The recent coronavirus disease 2019 pandemic has triggered an increase in medical waste. Conversely, it has disrupted the supply chain of personal protective equipment (PPE). Valorisation of food waste was performed to cultivate C. necator for fermentative production of biopolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The increase in biomass, PHBV yield and molar 3-hydroxy valerate (3HV) content was estimated after feeding volatile fatty acids. The fed-batch fermentation strategy reported in this study produced 15.65 ± 0.14 g/L of biomass with 5.32 g/L of PHBV with 50% molar 3HV content. This is a crucial finding, as molar concentration of 3HV can be modulated to suit the specification of biopolymer (film or fabric). The strategy applied in this study addresses the issue of global food waste burden and subsequently generates biopolymer PHBV, turning waste to wealth.

The replacement of fossil fuels with clean and renewable biofuels is of both research and market interest for realising a circular economy. However, microalgae-based biofuels have shown promise as alternative low-carbon biofuels to other crop-based biofuels, some key obstacles in their production remain to be addressed, such as high costs and low lipid productivity. In this study, a Chlorella sp. CSH4 was cultivated using a combined light regime and carbon supply regulation strategy to enhance sugar industrial wastewater bioremediation, biomass accumulation and lipid production. Blue light irradiance of 200 μmol photons m -2 s-1 together with 10 g/L glucose and 9.2 g/L glycerol supply was found to effectively enhance the biomass accumulation and pollutant-removal capacity of Chlorella sp. during the growth phase and its lipid production during the stationary phase. Furthermore, the biodiesel properties of the lipid retrieved from Chlorella sp., as demonstrated by its fatty acid profile, were found to be suitable for commercial application. Possible mechanisms were explored to explain how this combined strategy caused this microalga to exhibit highly efficient biomass and lipid production together with efficient pollutant removal. Moreover, upscaled semi-continuous treatment using both sugar industry wastewater and negligible carbon sources (e.g., food waste hydrolysate and crude glycerol) with a mass balance analysis was conducted to initially validate the feasibility of applying our combined strategy for microalgae based wastewater treatment. In sum, this study demonstrated the feasibility of cultivating a microalga using a combined strategy comprising a light regime and carbon supply regulation to achieve both wastewater treatment and low-carbon biofuel production., peer-reviewed

In their Editorial to the Special Issue on The Chemistry of Waste Plastics Upcycling, the Guest Editors Adam Guss, George Huber, Carol Lin, Xianzhi Meng, Hugh O'Neill, Arthur Ragauskas, Jia Wang, Yanqin Wang, and Frederik Wurm highlight some of the increasingly urgent efforts being made by chemists to address challenges related to the fate of plastics at the end of, their useful lives and the valorization of plastic waste.

International audience; Yarrowia lipolytica strains PGC01003 and PGC202 engineered for succinic acid production were studied and compared to the wild type strain W29. For the first time, these two strains were characterized in a chemically defined medium. Strain growth and organic acid production were investigated in fed-batch mode with glycerol as carbon and energy source. This study evaluated the impact of nitrogen deficiency strategy to redirect carbon flux toward succinic acid synthesis. Strain PGC01003 produced 19 g L−1 succinic acid with an overall yield of 0.23 g g−1 and an overall productivity of 0.23 g L−1 h−1, while strain PGC202 produced 33 g L−1 succinic acid with an overall yield of 0.12 g g−1 and a productivity of 0.57 g L−1 h−1. Nitrogen limitation effectively stopped biomass growth and increased succinic acid yield of PGC01003 and PGC202 by 18 % and 62 %, respectively. However, the specific succinic acid production rate was reduced by 77 % and 66 %, respectively.

Although fossil-based plastic products have many attractive characteristics, their production has led to severe environmental burdens that require immediate solutions. Despite these plastics being non-natural chemical compounds, they can be degraded and metabolized by some microorganisms, which suggests the potential application of biotechnologies based on the mechanism of plastic biodegradation. In this context, microbe-based strategies for the degradation, recycling, and valorization of plastic waste offer a feasible approach for alleviating environmental challenges created by the accumulation of plastic waste. This Minireview highlights recent advances in the biotechnology-based biodegradation of both traditional polymers and bio-based plastics, focusing on the mechanisms of biodegradation. From an application perspective, this Minireview also summarizes recent progress in the recycling and valorization of plastic waste, which are feasible solutions for tackling the plastic waste dilemma.

Due to the recent boom in urbanisation, economy, and global population, the amount of waste generated worldwide has increased tremendously. The World Bank estimates that global waste generation is expected to increase 70% by 2050. Disposal of waste is already a major concern as it poses risks to the environment, human health, and economy. To tackle this issue and maximise potential environmental, economic, and social benefits, waste valorisation - a value-adding process for waste materials - has emerged as a sustainable and efficient strategy. The major objective of waste valorisation is to transit to a circular economy and maximally alleviate hazardous impacts of waste. This review conducts bibliometric analysis to construct a co-occurrence network of research themes related to management of five major waste streams (i.e., food, agricultural, textile, plastics, and electronics). Modern valorisation technologies and their efficiencies are highlighted. Moreover, insights into improvement of waste valorisation technologies are presented in terms of sustainable environmental, social, and economic performances. This review summarises highlighting factors that impede widespread adoption of waste valorisation, such as technology lock-in, optimisation for local conditions, unfavourable regulations, and low investments, with the aim of devising solutions that explore practical, feasible, and sustainable means of waste valorisation.

Recent sustainable development goals of food security, environmental protection, material and energy efficiency are the key drivers of the valorization of food waste. In the present work, the production of biosurfactant sophorolipids from several (food) waste streams was investigated, using the non-pathogenic yeast Starmerella bombicola. From a preliminary screening, restaurant food waste emerged as the most suitable feedstock compared to bakery waste, textile waste, used corn oil, animal fat and lipid fraction of hydrolyzed food waste. Restaurant food waste was subsequently used for sophorolipids production in a laboratory-scale bioreactor. Food waste obtained from a local restaurant was subjected to enzymatic hydrolysis for 16 h, yielding a hydrolysate containing about 100 g/L glucose and 2.4 g/L free amino nitrogen. High SL process efficiency was achieved by fed-batch fermentation using the restaurant food waste hydrolysate as the complete batch medium, i.e. without any supplementation of additional medium components such as vitamins, salts, nitrogen or phosphate. Controlled feeding of glucose and oleic acid to the culture was performed after the batch phase. A sophorolipids titer of 115.2 g/L was obtained in a fermentation time of 92 h resulting in an overall volumetric productivity of 1.25 g/L.h. These results achieved for sophorolipids productivity using hydrolyzed food waste are in the same order of magnitude as the reported values using traditional (complex) fermentation media. This indicates the suitability of the developed process using food waste for the advancement of waste-based bio-processes for the production of sophorolipids.

This paper presents an efficient, green and sustainable approach for succinic acid (SA) fermentation, in which glucose-rich hydrolysates from various waste streams were used as the substrate for SA production by Yarrowia lipolytica without pH control for the first time. First, Y. lipolytica PGC202 was found to be able to consume glucose-rich mixed food waste (MFW) hydrolysate for SA production with high efficiency. After medium optimization, a SA titer at 31.7 g/L with a yield of 0.52 g/g and productivity of 0.60 g/L/h was obtained from isFBB fermentation when using 60 g/L glucose-containing MFW hydrolysate as the carbon source supplemented with 3% tryptone. When glucose-rich hydrolysate from other waste streams was used, the highest SA yield of 0.61 g/g via yeast fermentation at low pH was achieved, which demonstrated the extensive substrate adaptability and great potential of Y. lipolytica. By feeding concentrated MFW hydrolysate, SA titer up to 71.6 g/L was achieved from fed-batch fermentation with pH decreased naturally to 2.8. Finally, with the revised recovery method, 68.3% of the total SA with purity between 89.5% and 91.0% was recovered from the acidic fermentation broth with only low input of acid for acidification, which demonstrated the great advantages of SA production at low pH over that under neutral conditions in terms of economic improvement and environmental sustainability. In general, this study overcomes one of the major economic drawbacks for future feasible large-scale fermentative SA production, and it also illustrates a promising prospective for bio-SA production.

Coupling microalgae cultivation with wastewater treatment is a promising strategy to purify the waste streams and harvest the enhanced biomass production. In this study, an oleaginous alga Scenedesmus obliquus that was isolated from the dairy wastewater was examined for its bioremediation of municipal wastewater. Water samples, including raw and treated ones, were collected from three wastewater treatment plants at different scales. Under indoor conditions, S. obliquus showed strong nutrient removal efficiency, with nitrogen and phosphorus removal rates being over 99%. The alga grew faster in the raw wastewater (specific growth rates: 0.37−0.45 d−1), whereas more lipids accumulated in the treated wastewater (31.45–35.74%of dry weight). The raw wastewater-based culture was subsequently enlarged by using panel photo-bioreactors (PBRs) in semi-continuous mode. Such outdoor cultivations were conducted twice in different seasons, reflecting the impacts of environmental fluctuation. Results showed that under the natural condition, the hydraulic retention time (HRT)-based culture was significantly impacted by the changeable temperatures and illumination; instead, replacing the medium (i.e. raw wastewater) following biomass concentration rather than HRT made the culture system more stable. An average biomass productivity of 0.22 g L−1 d−1 was obtained, regardless of the changing environmental conditions. These findings may advance the knowledge of employing S. obliquus for raw wastewater treatment at the industrial scale.

This study focused on the feasibility of Y. lipolytica PSA02004 co-utilising glucose and xylose from sugarcane bagasse hydrolysate in succinic acid (SA) fermentation. Optimum pH, temperature and cellulase dosage of enzymatic hydrolysis through optimisation were pH 5, 50 °C and 40 FPU/g, respectively. The hydrolysis yields for glucose and xylose were 0.35 ± 0.00 g/g and 0.15 ± 0.00 g/g, respectively. A feasibility study using a 2.5-L bioreactor demonstrated that mixed glucose and xylose could be utilised for SA production, with the resultant SA titre, yield and productivity of 28.2 ± 0.6 g/L, 0.55 ± 0.01 g/g and 0.36 ± 0.01 g/L/h, respectively. Then, the investigation of nutrient-limiting factor showed 40 g/L of initial glucose concentration and 8.4 g/L of initial xylose concentration containing hydrolysate and 2% CSL were the optimum medium composition in SA fermentation. SA production using sugarcane bagasse hydrolysate was conducted, in which SA titre, yield and productivity were 33.2 ± 0.3 g/L, 0.58 ± 0.01 g/g and 0.33 ± 0.01 g/L/h, respectively. The experimental results reported in this study show that glucose and xylose in sugarcane bagasse hydrolysate were successfully co-utilised by Y. lipolytica PSA02004 in SA production. This implies a sugarcane waste biorefinery could lead to a generic feedstock for the efficient production of succinic acid.