A novel integrated approach employing Desertifilum tharense BERC-3 for efficient wastewater valorization and recycling for developing peri-urban algae farming system.

Peri-urban environments are significant reservoirs of wastewater, and releasing this untreated wastewater from these resources poses severe environmental and ecological threats. Wastewater mitigation through sustainable approaches is an emerging area of interest. Algae offers a promising strategy for carbon-neutral valorization and recycling of urban wastewater. Aiming to provide a proof-of-concept for complete valorization and recycling of urban wastewater in a peri-urban environment in a closed loop system, a newly isolated biocrust-forming cyanobacterium Desertifilum tharense BERC-3 was evaluated. Here, the highest growth and lipids productivity were achieved in urban wastewater compared to BG11 and synthetic wastewater. D. tharense BERC-3 showed 60-95% resource recovery efficiency and decreased total dissolved solids, chemical oxygen demand, biological oxygen demand, nitrate nitrogen, ammonia nitrogen and total phosphorus contents of the water by 60.37%, 81.11%, 82.75%, 87.91%, 85.13%, 85.41%, 95.87%, respectively, making it fit for agriculture as per WHO's safety limits. Soil supplementation with 2% wastewater cultivated algae as a soil amender, along with its irrigation with post-treated wastewater, improved the nitrogen content and microbial activity of the soil by 0.3-2.0-fold and 0.5-fold, respectively. Besides, the availability of phosphorus was also improved by 1.66-fold. The complete bioprocessing pipeline offers complete biomass utilization. This study demonstrated the first proof-of-concept of integrating resource recovery and resource recycling using cyanobacteria to develop a peri-urban algae farming system. This can lead to establishing wastewater-driven algae cultivation systems as novel enterprises for rural migrants moving to urban areas.

Immobilization of rough morphotype Mycolicibacterium neoaurum R for androstadienedione production.

OBJECTIVES: Enhance the androstadienedione (Androst-1,4-diene-3,17-dione, ADD) production of rough morphotype Mycolicibacterium neoaurum R by repeated-batch fermentation of immobilized cells. RESULTS: M. neoaurum R was a rough colony morphotype variant, obtained from the routine plating of smooth M. neoaurum strain CICC 21097. M. neoaurum R showed rougher cell surface and aggregated in broth. The ADD production of M. neoaurum R was notably lower than that of M. neoaurum CICC 21097 during the free cell fermentation, but the yield gap could be erased after proper cell immobilization. Subsequently, repeated-batch fermentation of immobilized M. neoaurum R was performed to shorten the production cycle and enhance the bio-production efficiency of ADD. Through the optimization of the immobilization carriers and the co-solvents for phytosterols, the ADD productivity of M. neoaurum R immobilized by semi-expanded perlite reached 0.075 g/L/h during the repeated-batch fermentation for 40 days. CONCLUSIONS: The ADD production of the rough-type M. neoaurum R was notably enhanced by the immobilization onto semi-expanded perlite. Moreover, the ADD batch yields of M. neoaurum R immobilized by semi-expanded perlite were maintained at high levels during the repeated-batch fermentation.

Employing Cationic Kraft Lignin as Additive to Enhance Enzymatic Hydrolysis of Corn Stalk.

A water-soluble cationic kraft lignin (named JLQKL50), synthesized by combining quaternization and crosslinking reactions, was used as an additive to enhance the enzymatic hydrolysis of dilute-alkali-pretreated corn stalk. The chemical constitution of JLQKL50 was investigated by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR) and 13C NMR spectroscopy, and elemental analysis. The enzymatic hydrolysis efficiency of corn stalk at solid content of 10% (w/v) was significantly improved from 70.67% to 78.88% after 24 h when JLQKL50 was added at a concentration of 2 g/L. Meanwhile, the enzymatic hydrolysis efficiency after 72 h reached 91.11% with 10 FPU/g of cellulase and 97.92% with 15 FPU/g of cellulase. In addition, JLQKL50 was found capable of extending the pH and temperature ranges of enzymatic hydrolysis to maintain high efficiency (higher than 70%). The decrease in cellulase activity under vigorous stirring with the addition of JLQKL50 was 17.4%, which was much lower than that (29.7%) without JLQKL50. The addition of JLQKL50 reduced the nonproductive adsorption of cellulase on the lignin substrate and improved the longevity, dispersity, and stability of the cellulase by enabling electrostatic repulsion. Therefore, the enzymatic hydrolysis of the corn stalk was enhanced. This study paves the way for the design of sustainable lignin-based additives to boost the enzymatic hydrolysis of lignocellulosic biomass.

Determination of active sites on the synthesis of novel Lewis acidic deep eutectic solvent catalysts and kinetic studies in microalgal biodiesel production.

Experimental and theoretical considerations for kinetic modeling of the transesterification reaction of microalgae lipids into biodiesel were investigated using Lewis acid deep eutectic solvents (DESs) as a catalyst. The acid sites involved in the reaction were characterized using acetonitrile as a probe to understand the mechanism. DES ChCl-SnCl2 (choline chloride-tin ii chloride) showed higher catalytic activity in transesterification due to its higher acidity compared to DES ChCl-ZnCl2 (choline chloride-zinc chloride). This was illustrated by geometric optimization of the DES structures through density functional theory (DFT) which showed that the metal centers furthest from the choline moiety are the most acidic and the bond lengths of Sn-Cl were between 2.56 and 2.77 Å, and were greater than the Zn-Cl bond lengths from 2.30 to 2.48 Å, making the ChCl-SnCl2 DES more acidic and more suitable for the biodiesel production. The fatty acid methyl ester (FAME) conversion from microalgae lipid was 36.75 mg g-1 under ideal conditions (6 molar ratio methanol-lipid with 8 vol% DES dosage in methanol at 140 °C for 420 min). The activation energy is found to be 36.3 kJ mol-1 based on the pseudo-first-order reaction, in addition, the DES catalyst (ChCl-SnCl2) drove the reaction chemically and did not show mass transfer limitation. Information from this study can help to advance the development of an efficient and environmentally friendly industrial biodiesel production technology.

Engineering an efficient whole-cell catalyst for d-allulose production from glycerol.

d-Allulose has many health-benefiting properties and therefore sustainably applied in food, pharmaceutical, and nutrition industries. The aldol reaction-based route is a very promising alternative to Izumoring strategy in d-allulose production. Remarkable studies reported in the past cannot get rid of by-product formation and costly purified enzyme usage. In the present study, we explored the glycerol assimilation by modularly assembling the d-allulose synthetic cascade in Escherichia coli envelop. We achieved an efficient whole-cell catalyst that produces only d-allulose from cheap glycerol feedstock, eliminating the involvement of purified enzymes. Detailed process optimization improved the d-allulose titer by 1500.00%. Finally, the production was validated in 3-L scale using a 5-L fermenter, and 5.67 g L-1 d-allulose was produced with a molar yield of 31.43%.

Magnetic biochar promotes the risk of mobile genetic elements propagation in sludge anaerobic digestion.

Mobile genetic elements (MGEs) mediated horizontal gene transfer is the primary reason for the propagation of antibiotic resistance genes in environment. The behavior of MGEs under magnetic biochar pressure in sludge anaerobic digestion (AD) is still unknown. This study evaluated the effects of different dosage magnetic biochar on the MGEs in AD reactors. The results showed that the biogas yield was highest (106.68 ± 1.16 mL g-1 VSadded) with adding optimal dosage of magnetic biochar (25 mg g-1 TSadded), due to it increased the microorganism's abundance involved in hydrolysis and methanogenesis. While, the total absolute abundance of MGEs in the reactors with magnetic biochar addition increased by 11.58%-77.37% compared with the blank reactor. When the dosage of magnetic biochar was 12.5 mg g-1 TSadded, the relative abundance of most MGEs was the highest. The enrichment effect on ISCR1 was the most significant, and the enrichment rate reached 158.90-214.16%. Only the intI1 abundance was reduced and the removal rates yield 14.38-40.00%, which was inversely proportional to the dosage of magnetic biochar. Co-occurrence network explored that Proteobacteria (35.64%), Firmicutes (19.80%) and Actinobacteriota (15.84%) were the main potential host of MGEs. Magnetic biochar changed MGEs abundance by affecting the potential MGEs-host community structure and abundance. Redundancy analysis and variation partitioning analysis showed that the combined effect of polysaccharides, protein and sCOD exhibited the greatest contribution (accounted for 34.08%) on MGEs variation. These findings demonstrated that magnetic biochar increases the risk of MGEs proliferation in AD system.

Produce D-allulose from non-food biomass by integrating corn stalk hydrolysis with whole-cell catalysis.

D-allulose is a high-value rare sugar with many health benefits. D-allulose market demand increased dramatically after approved as generally recognized as safe (GRAS). The current studies are predominantly focusing on producing D-allulose from either D-glucose or D-fructose, which may compete foods against human. The corn stalk (CS) is one of the main agricultural waste biomass in the worldwide. Bioconversion is one of the promising approach to CS valorization, which is of significance for both food safety and reducing carbon emission. In this study, we tried to explore a non-food based route by integrating CS hydrolysis with D-allulose production. Firstly we developed an efficient Escherichia coli whole-cell catalyst to produce D-allulose from D-glucose. Next we hydrolyzed CS and achieved D-allulose production from the CS hydrolysate. Finally we immobilized the whole-cell catalyst by designing a microfluidic device. Process optimization improved D-allulose titer by 8.61 times, reaching 8.78 g/L from CS hydrolysate. With this method, 1 kg CS was finally converted to 48.87 g D-allulose. This study validated the feasibility of valorizing corn stalk by converting it to D-allulose.

Effect of functional group and structure on hydrophobic properties of environment-friendly lignin-based composite coatings.

Hydrophobic coatings are widely used in a variety of materials surfaces. However, it remains a great challenge for the non-toxic and environmentally-friendly production of hydrophobic coatings. Herein, two nano-scale spherical lignin/SiO2 composite particles are synthesized based on the electrostatic interaction and the steric hindrance effect inspired by the self-protection of straw. Introduction of positively charged quaternary ammonium enhances the possibility of electrostatic self-assembly between lignin and SiO2 for QAL/SiO2, and access of super-long hydrophobic chains induces the formation of nano-sized particles for QALC12/SiO2. The coatings were fabricated by simply spraying on substrates and hydrophilic/hydrophobic properties were detected. The results show that the long hydrophobic chain can enhance the hydrophobic properties of lignin polymers (CA = 129°) and the spherical micro-nano structure is beneficial to improve the hydrophobic properties of the lignin/SiO2 composite (CA = 137°). Meanwhile, the hydrophobic coating has good self-cleaning performance. The excellent hydrophobic and self-cleaning properties are mainly benefited from the nano effect, reasonable hydrophilic/hydrophobic structure, and good dispersibility of spherical structure. This work not only provides a kind of lignin-based nano-scale waterproof coatings holding excellent properties in terms of cost, scalability, and robustness, but also has important significance for the high-value utilization of biomass resources.

Mycolicibacterium cell factory for the production of steroid-based drug intermediates.

Steroid-based drugs have been developed as the second largest medical category in pharmaceutics. The well-established route of steroid industry includes two steps: the conversion of natural products with a steroid framework to steroid-based drug intermediates and the synthesis of varied steroid-based drugs from steroid-based drug intermediates. The biosynthesis of steroid-based drug intermediates from phytosterols by Mycolicibacterium cell factories bypasses the potential undersupply of diosgenin in the traditional steroid chemical industry. Moreover, the biosynthesis route shows advantages on multiple steroid-based drug intermediate products, more ecofriendly processes, and consecutive reactions carried out in one operation step and in one pot. Androsta-4-ene-3,17-dione (AD), androsta-1,4-diene-3,17-dione (ADD) and 9-hydroxyandrostra-4-ene-3,17-dione (9-OH-AD) are the representative steroid-based drug intermediates synthesized by mycolicibacteria. Other steroid metabolites of mycolicibacteria, like 4-androstene-17ß-ol-3-one (TS), 22-hydroxy-23,24-bisnorchol-4-ene-3-one (4-HBC), 22-hydroxy-23,24-bisnorchol-1,4-diene-3-one (1,4-HBC), 9,22-dihydroxy-23,24-bisnorchol-4-ene-3-one (9-OH-HBC), 3aα-H-4α-(3'-propionic acid)-7aß-methylhexahydro-1,5-indanedione (HIP) and 3aα-H-4α-(3'-propionic acid)-5α-hydroxy-7aß-methylhexahydro-1-indanone-δ-lactone (HIL), also show values as steroid-based drug intermediates. To improve the bio-production efficiency of the steroid-based drug intermediates, mycolicibacterial strains and biotransformation processes have been continuously studied in the past decades. Many mycolicibacteria that accumulate steroid drug intermediates have been isolated, and subsequently optimized by conventional mutagenesis and genetic engineering. Especially, with the clarification of the mycolicibacterial steroid metabolic pathway and the developments on gene editing technologies, rational design is becoming an important measure for the construction and optimization of engineered mycolicibacteria strains that produce steroid-based drug intermediates. Hence, by reviewing researches in the past two decades, this article updates the overall process of steroid metabolism in mycolicibacteria and provides comprehensive schemes for the rational construction of mycolicibacterial strains that accumulate steroid-based drug intermediates. In addition, the special strategies for the bioconversion of highly hydrophobic steroid in aqueous media are discussed as well.

Recent Advances in Producing Sugar Alcohols and Functional Sugars by Engineering Yarrowia lipolytica.

The sugar alcohols and functional sugars have wide applications in food, pharmaceutical, and chemical industries. However, the smaller quantities of natural occurring sugar alcohols and functional sugars restricted their applications. The enzymatic and whole-cell catalyst production is emerging as the predominant alternatives. The properties of Yarrowia lipolytica make it a promising sugar alcohol and functional sugar producer. However, there are still some issues to be resolved. As there exist reviews about the chemical structures, physicochemical properties, biological functions, applications, and biosynthesis of sugar alcohols and/or functional sugars in Y. lipolytica, this mini review will not only update the recent advances in enzymatic and microbial production of sugar alcohols (erythritol, D-threitol, and xylitol) and functional sugars (isomaltulose, trehalose, fructo-oligosaccharides, and galacto-oligosaccharides) by using recombinant Y. lipolytica but also focus on the studies of gene discovery, pathway engineering, expanding substrate scope, bioprocess engineering, and novel breeding methods to resolve the aforementioned issues.

One-pot preparation of hydrophobic lignin/SiO2 nanoparticles and its reinforcing effect on HDPE.

Nano silica (SiO2) is usually used as a common reinforcing agent in polymer materials, in which the interfacial interaction greatly affects the mechanical properties of the composites. The reinforcement effect of silica on non-polar polymer is restricted due to their poor compatibility. In this work, amphipathic lignin modified by quaternization and alkylation was used as a modifier for silica to prepare hydrophobic lignin/SiO2 nanoparticles by in-situ one-pot co-precipitation method. In alkaline solution, hydrophobic lignin and SiO2 (from Na2SiO3) were self-assembled to form nanospheres through electrostatic and hydrophobic interactions. The results showed that the lignin/SiO2 nanoparticles were highly hydrophobic nanospheres with macropores in the surface. When the lignin/SiO2 nanoparticles (10 wt%) were added to reinforce high-density polyethylene (HDPE), the mechanical properties of HDPE were improved with the strength of 24.5 MPa and the elongation of 1096%, which were increased by 10.4% and 14.3% compared with the control HDPE, because of the good compatibility and large bonding area. This work puts forward a new solution for the application of lignin in reinforcement of non-polar polymers.

Al-doped α-MnO2 coated by lignin for high-performance rechargeable aqueous zinc-ion batteries.

Zn/MnO2 batteries, one of the most widely studied rechargeable aqueous zinc-ion batteries, suffer from poor cyclability because the structure of MnO2 is labile with cycling. Herein, the structural stability of α-MnO2 is enhanced by simultaneous Al3+ doping and lignin coating during the formation of α-MnO2 crystals in a hydrothermal process. Al3+ enters the [MnO6] octahedron accompanied by producing oxygen vacancies, and lignin further stabilizes the doped Al3+ via strong interaction in the prepared material, Al-doped α-MnO2 coated by lignin (L + Al@α-MnO2). Meanwhile, the conductivity of L + Al@α-MnO2 improves due to Al3+ doping, and the surface area of L + Al@α-MnO2 increases because of the production of nanorod structures after Al3+ doping and lignin coating. Compared with the reference α-MnO2 cathode, the L + Al@α-MnO2 cathode achieves superior performance with durably high reversible capacity (∼180 mA h g-1 at 1.5 A g-1) and good cycle stability. In addition, ex situ X-ray diffraction characterization of the cathode at different voltages in the first cycle is employed to study the related mechanism on improving battery performance. This study may provide ideas of designing advanced cathode materials for other aqueous metal-ion batteries.

Biosynthesis of lactones from diols mediated by an artificial flavin.

BACKGROUND: Lactones are important compounds in the field of medicine, material and chemical industry. One of the promising accesses to these flexible scaffolds is NAD(P)+-dependent alcohol dehydrogenases-catalyzed oxidative lactonization of diols, which relies on the construction of an efficient NAD(P)+ regeneration system. RESULTS: In this study, a novel system combining horse liver alcohol dehydrogenase (HLADH) with the synthetic bridged flavin cofactor was established for biosynthesis of lactones. The reaction conditions of this system were optimized and a variety of lactones including chiral lactones were efficiently obtained from various diols. Compared to the previously reported NAD(P)+-regeneration systems, this system showed better regeneration efficiency and product yield. A two-phase system was further applied to solve the problem of product inhibition, and 80% yield was obtained at the condition of 300 mM substrate. CONCLUSIONS: This study provides an efficient method to synthesis of lactones from diols under mild conditions. We believe this system will be a promising alternative to promote the synthesis of other valuable compounds.

Process optimization for the production of high-concentration ethanol with Scenedesmus raciborskii biomass.

Scenedesmus raciborskii WZKMT was subjected to fed-batch enzymatic hydrolysis and fermentation to facilitate the saccharification of high-solid-loading substrate for high-concentration ethanol. In this work, process factors affecting enzymatic hydrolysis, including enzyme loading, temperature, pH, and solid loading, were optimized. Results showed that 58.03 g L-1 glucose, 12.57 g L-1 xylose, and 1.45 g L-1 cellobiose were obtained after the enzymatic hydrolysis of 330 g L-1 substrates under the optimal conditions of 30 FPU g-1 enzyme loading, 50 °C, and pH 5.5. Meanwhile, 89.60% yield and 30.43 g L-1 content of ethanol were obtained after the fermentation of 330 g L-1 hydrolysate. The maximum ethanol concentration of 79.38 g L-1 could be achieved through repeated fed-batch process, indicating that S. raciborskii WZKMT is a promising feedstock for ethanol production.