While the expansion of the erythritol production industry has resulted in unprecedented production of yeast cells, it also suffers from a lack of effective utilization. β-Carotene is a value-added compound that can be synthesized by engineered Yarrowia lipolytica. Here, we first evaluated the production performance of erythritol-producing yeast strains under two different morphologies and then successfully constructed a chassis with yeast-like morphology by deleting Mhy1 and Cla4 genes. Subsequently, β-carotene synthesis pathway genes, CarRA and CarB from Blakeslea trispora, were introduced to construct the β-carotene and erythritol coproducing Y. lipolytica strain ylmcc. The rate-limiting genes GGS1 and tHMG1 were overexpressed to increase the β-carotene yield by 45.32-fold compared with the strain ylmcc. However, increased β-carotene accumulation led to prolonged fermentation time; therefore, transporter engineering through overexpression of YTH1 and YTH3 genes was used to alleviate fermentation delays. Using batch fermentation in a 3 L bioreactor, this engineered Y. lipolytica strain produced erythritol with production, yield, and productivity values of 171 g/L, 0.56 g/g glucose, and 2.38 g/(L·h), respectively, with a concomitant β-carotene yield of 47.36 ± 0.06 mg/g DCW. The approach presented here improves the value of erythritol-producing cells and offers a low-cost technique to obtain hydrophobic terpenoids.

As an abundant H2-rich byproduct from coking production, coke oven gas (COG) is a favorable feedstock for ammonia production. Recently, three COG-based ammonia processes have been applied, including single process, coproduction of ammonia with methanol, and coproduction of ammonia with liquefied natural gas (LNG). To systematically evaluate the environmental impacts of three COG routes, a comparative life cycle assessment was conducted with industrial data. Besides, the effects of ammonia synthesis pressure and electricity sources to the total LCA result were discussed. The results indicate that the environmental impacts of COG-based single ammonia route are mainly generated from ammonia production stage, accounting for 69.63 % of the overall normalized results, in which electricity and COG are the dominated contributors. Therefore, employing electricity from renewables like wind, solar, hydro and nuclear could dramatically mitigate the environmental impacts with a reduction of 36.3 %-70.7 % in most environmental indicators. Scenario analysis proves that reducing synthesis pressure from 31.4 MPa to 15 MPa does not show remarkable environmental benefits as expected since higher pressure is more conducive to ammonia synthesis. In comparison with coal based and natural gas-based ammonia routes, COG routes have obvious energy-saving benefit. In three COG-based ammonia routes, the two coproduction routes accounted for 49.1 % and 78.6 % of the energy depletion as single production due to highly efficient utilization of resources and energy. Coproduction of ammonia with methanol route exhibits better environmental performance than these in coproduction of ammonia with LNG route. Therefore, coproduction of ammonia with methanol route is more favorable in COG to ammonia processes. This study intends to provide a valuable reference for COG utilization and ammonia production options through the life cycle aspect.

Bioconversion of natural microorganisms generally results in a mixture of various compounds. Downstream processing (DSP) which only targets a single product often lacks economic competitiveness due to incomplete use of raw material and high cost of waste treatment for by-products. Here, we show with the efficient microbial conversion of crude glycerol by an artificially evolved strain and how a catalytic conversion strategy can improve the total products yield and process economy of the DSP. Specifically, Clostridium pasteurianum was first adapted to increased concentration of crude glycerol in a novel automatic laboratory evolution system. At m3 scale bioreactor the strain achieved a simultaneous production of 1,3-propanediol (PDO), acetic and butyric acids at 81.21, 18.72, and 11.09 g/L within only 19 h, respectively, representing the most efficient fermentation of crude glycerol to targeted products. A heterogeneous catalytic step was developed and integrated into the DSP process to obtain high-value methyl esters from acetic and butyric acids at high yields. The coproduction of the esters also greatly simplified the recovery of PDO. For example, a cosmetic grade PDO (96% PDO) was easily obtained by a simple single-stage distillation process (with an overall yield more than 77%). This integrated approach provides an industrially attractive route for the simultaneous production of three appealing products from the crude glycerol fermentation broth, which greatly improve the process economy and ecology.

The COVID-19 pandemic created a critical need for citizen volunteers working with government to protect public health and to augment overwhelmed public services. Our research examines the crucial role of community volunteers and their effective deployment during a crisis. We analyze individual and collaborative service activities based on usage data from 85,699 COVID-19 volunteers gathered through China\'s leading digital volunteering platform, as well as a survey conducted among a sample of 2,270 of these COVID-19 volunteers using the platform and interviews with 14 civil society leaders in charge of coordinating service activities. Several results emerge: the value of collaboration among local citizens, civil society including community-based groups, and regional government to fill gaps in public services; the key role of experienced local volunteers, who rapidly shifted to COVID-19 from other causes as the pandemic peaked; and an example of state-led coproduction based on long-term relationships. Our analysis provides insight into the role of volunteerism and coproduction in China\'s response to the pandemic, laying groundwork for future research. The findings can help support the response to COVID-19 and future crises by more effectively leveraging human capital and technology in community service delivery.

This work proposed an integrated process based on alkali-sulfite (AlkSul) pretreatment to coproduce fermentable sugars and lignin adsorbents from hardwood. Different from conventional liquid hot water (LHW) pretreatment, this pretreatment improved cellulose accessibility through selective lignin removal and modification, resulting in significantly enhanced biomass saccharification. Over 75% of the original cellulose and hemicellulose was released and could be recovered as fermentable sugars after pretreatment and subsequent enzymatic hydrolysis. Meanwhile, lignin residues from pretreatment hydrolysate and enzymatic hydrolysate showed lead ions adsorption capacities of 156.25 and 68.49 mg/g, respectively, indicating both streams of lignin residues were favorable adsorbents for heavy metal ions. The improved adsorption capacity of lignin residues was primarily due to the lignin modification as sulfur-containing functional groups incorporation during the integrated pretreatment. Results demonstrated the integrated alkali-sulfite pretreatment improved biomass saccharification, while coproducing lignin adsorbents for wastewater treatment, which can promote the sustainability of lignocellulosic biorefinery.

The biosynthesis of isoprene by microorganisms is a promising green route. However, the yield of isoprene is limited due to the generation of excess NAD(P)H via the mevalonate (MVA) pathway, which converts more glucose into CO2 or undesired reduced by-products. The production of 1,3-propanediol (1,3-PDO) from glycerol is a typical NAD(P)H-consuming process, which restricts 1,3-PDO yield to ~ 0.7 mol/mol. In this study, we propose a strategy of redox cofactor balance by coupling the production of isoprene with 1,3-PDO fermentation. With the introduction and optimization of the dual pathways in an engineered Escherichia coli, ~ 85.2% of the excess NADPH from isoprene pathway was recycled for 1,3-PDO production. The best strain G05 simultaneously produced 665.2 mg/L isoprene and 2532.1 mg/L 1,3-PDO under flask fermentation conditions. The yields were 0.3 mol/mol glucose and 1.0 mol/mol glycerol, respectively, showing 3.3- and 4.3-fold improvements relative to either pathway independently. Since isoprene is a volatile organic compound (VOC) whereas 1,3-PDO is separated from the fermentation broth, their coproduction process does not increase the complexity or cost for the separation from each other. Hence, the presented strategy will be especially useful for developing efficient biocatalysts for other biofuels and biochemicals, which are driven by cofactor concentrations.

In this work, chondroitin sulfate (CS) was extracted from chicken leg bone soup using the heat-resin static adsorption extraction (HSAE) method. The HSAE method was optimized as follows: resin dosage, 10%; adsorption time, 4.3 h; eluent concentration, 2 M; eluent time, 1.3 h, under which the yield of CS1 from the bone soup reached 0.14% and the recovery rate was 67.35%. CS2, as reference, was obtained from the ends of chicken leg bone using enzymatic method. CS1 and CS2, together with other glycosaminoglycans, were confirmed using agarose-gel electrophoresis. The average molecular weight of CS1 and CS2 was 35.81 kDa and 37.18 kDa, respectively. The structures of CS1 and CS2 were compared using Fourier-transform infrared spectroscopy and high-performance liquid chromatography, and no significant difference was observed. Overall, the HSAE method was proposed to be a promising approach for the coproduction of CS and bone soup.

Single-cell biorefineries are an interesting strategy for using different components of feedstock to produce multiple high-value biochemicals. In this study, a strategy was applied to refine glucose and fatty acid to produce 5-aminolevulinic acid (ALA) and polyhydroxyalkanoates (PHAs). To express the ALA and PHAs dual-production system efficiently and stably, multiple copies of the poly-β-3-hydroxybutyrate (PHB) synthesis operon were integrated into the chromosome of Escherichia coli DH5αΔpoxB. The above strain harboring the ALA C5 synthesis pathway genes hemA and hemL resulted in coproduction of 38.2% PHB (cell dry weight, CDW) and 3.2 g/L extracellular ALA. To explore coproduction of ALA and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), the PHBV synthetic pathway was also integrated into engineered E. coli and coexpressed with hemA and hemL; cells produced 38.9% PHBV (CDW) with 10.3 mol% 3HV fractions and 3.0 g/L ALA. The coproduction of ALA with PHB and PHBV can improve the utilization of carbon sources and maximize the value derived from the feedstock.

Many biorefineries have not been commercialized due to poor economic returns from final products. In this work, a novel process has been developed to coproduce valuable sugars, xylo-oligosaccharides, and lignosulfonates from hardwood. The modified process includes a mild autohydrolysis pretreatment, which enables for the recovery of the xylo-oligosaccharides in auto-hydrolysate. Following enzymatic hydrolysis, the residue is sulfomethylated to produce lignosulfonates. Recycling the sulfomethylation residues increased both the glucan recovery and lignosulfonate production. The glucose recovery was increased from 81.7% to 87.9%. Steady state simulation using 100g of hardwood produced 46.7g sugars, 5.9g xylo-oligosaccharides, and 25.7g lignosulfonates, which were significantly higher than that produced from the no-recycling process with 39.1g sugars, 5.9g xylo-oligosaccharides, and 15.0g lignosulfonates. The results indicate that this novel biorefinery process can improve the production of fermentable sugars and lignosulfonate from hardwood as compared to a conventional biorefinery process.