Green Chemical Engineering最新文献

Ectoine is a natural macromolecule protector and synthesized by some extremophiles. It provides protections against radiation-mediated oxidative damages and is widely used as a bioactive ingredient in pharmaceutics and cosmetics. To meet its growing commercial demands, we engineered Escherichia coli strains for the high-yield production of ectoine. The ectABC gene cluster from the native ectoine producer Halomonas elongata was introduced into different Escherichia coli (E. Coil) strains via plasmids and 0.8 g L^-1 of ectoine was produced in flask cultures by engineered E. coli BL21 (DE3). Subsequently, we designed the ribosome-binding sites of the gene cluster to fine-tune the expressions of genes ectA, ectB, and ectC, which increased the ectoine yield to 1.6 g L^-1. After further combinatorial overexpression of Corynebacterium glutamicum aspartate kinase mutant (G1A, C932T) and the H. elongate aspartate-semialdehyde dehydrogenase to increase the supply of the precursor, the titer of ectoine reached to 5.5 g L^-1 in flask cultures. Finally, the engineered strain produced 60.7 g L^-1 ectoine in fed-batch cultures with a conversion rate of 0.25 g/g glucose.

To reduce the dependency on petroleum-based products and emission of greenhouse gas, renewable biofuels and chemicals play an important role to meet the unmatched energy demands of the rapidly growing population. However, most biofuel and chemical products do not reach the commercialization stage, mainly hindered by incomparable economics to petroproducts. Techno-economic assessment (TEA) is a useful tool to estimate economic performance, and identify bottlenecks for the development of biofuel and chemical production technology, meanwhile, life cycle assessment (LCA) is applied to assess sustainability by reducing the environmental impact of biofuel and chemical production. This present review covers TEA and LCA research progress in the manufacturing of biofuels and biochemical, and discusses the impacts of TEA and LCA results on the development and optimization of biofuel and chemical production. In addition, challenges associated with TEA and LCA of biofuel and biochemical production were briefly overviewed, and potential approaches that may overcome such challenges were discussed enabling viable and sustainable biomanufacturing of fuels and chemicals. Future integrated TEA and LCA studies could significantly promote the economic and sustainable development of the biomanufacturing process.

Nanocellulose has various outstanding properties and great potential for replacing petrochemical products. The utilization of lignocellulose to produce nanocellulose is of great significance to the sustainable development of the economy and society. However, the direct extraction of nanocellulose from lignocellulose by chemical method is challenged by toxic chemicals utilization, energy and time consumption, and waste water generation. Therefore, this paper addressed the conversion of lignocellulosic biomass into bacterial nanocellulose (BNC) by the biological method. Moreover, this article highlights the recent advances in potentials and challenges of lignocellulosic biomass for BNC production through the bioconversion process, including biomass pretreatment, enzymatic hydrolysis, glucose and xylose fermentation, GA accumulation, and inhibitor tolerant. The development in metabolic and evolutionary engineering to enhance the production capacity of BNC-producing strain is also discussed. It is expected to provide guidance on the effective bioproduction of nanocellulose from lignocellulosic biomass.

Methanol is becoming an attractive fermentation feedstock for large-scale bioproduction of chemicals, due to its natural abundance and mature production technology. Native methylotrophs, which can utilize methanol as the only source of carbon and energy, are ideal hosts for methanol bioconversion due to their high methanol utilization rate and have been extensively employed in the production of value-added chemicals from methanol. Here, we review the natural methanol utilization pathways in native methylotrophs, describing the available synthetic biology tools developed for engineering native methylotrophs, and discuss the strategies for improving their methanol utilization efficiency. Finally, the representative examples of engineering the native methylotrophs to produce value-added products from methanol are summarized. Furthermore, we also discuss the major challenges and possible solutions for the application of native methylotrophs in methanol-based biomanufacturing.

Glucose isomerase (GI) is an enzyme with high potential applications. Characterization of GI producing bacteria with interesting properties from an industrial point of view is essential. Bacillus sp., Paenarthrobacter sp., Chryseobacterium sp., Hymenobacter sp., Mycobacterium sp., and Stenotrophomonas sp. were isolated from soil samples. Optimization of enzyme production yield was investigated in various fermentation conditions using response surface methodology. All isolates exhibited maximum GI activity at 40 °C, pH 6–8 after 4 days of incubation. A mixture of peptone/yeast extract or tryptone/peptone enhanced higher enzyme production. The same trend was observed in fermentation medium containing 1% xylose or 2%–2.5% wheat straw. This study advanced the knowledge of these bacterial isolates in promoting wheat straw as feedstock for the bio-based industry.

With the rapid development of chemical engineering and biotechnology, polypeptide, as a promising candidate in the biomedical field, has been thoroughly investigated and extensively used as the drug delivery vehicle for diseases treatment, especially cancer, owing to the high biocompatibility, good biodegradability, versatile constructions, and diverse functions. Engineered polypeptide-based drug delivery system (so-called EPP-DDS) can deliver the cargos to the target site via a specific recognition effect, followed by overcoming the barriers like blood brain barrier (BBB) and releasing them by responding to the microenvironment cues, to improve the therapeutic efficacy and reduce the side-effect. Herein, it's of great importance to conclude and summarize the updates on EPP-DDS developed by chemical engineering methods. In this review, we first summarized the recent updates in the manufacturing of polypeptide and preparation of EPP-DDS based on green biochemical engineering and/or synthetic processes for cancer therapy, including chemotherapy, immunotherapy, photodynamic therapy (PDT), gene therapy, and combination therapy. Then, we surveyed the research progress of inflammation-mediated cancer treatment strategies based on EPP-DDS with high anti-inflammation activity. Finally, we concluded the discovery and green production process of engineered polypeptide, challenges, and perspectives of EPP-DDS. Overall, the EPP-DDS has great potential for cancer therapy in the clinic with improved therapeutic efficacy and reduced adverse effect, which needs the innovation of green biochemical engineering for customized design and production of polypeptides.

Cadaverine is the key monomer for the synthesis of nylon 5X. Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5. However, the most studied lysine decarboxylase CadA (E. coli) lost almost all activity at pH 8.0, which is the foremost challenge for the industrial-cadaverine production. In this study, we first found that the Na⁺-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylase ΔLdcEt3 (P233C/L628C) (half-life 362 h), compared to the conventional buffer (half-life 0.66 h) at pH 8.0. Meanwhile, the whole-cell conversion efficiency of the industrial-grade l-lysine with ΔLdcEt3 could reach up to 99% in 2 h in the fermenter. Experimental investigation and molecular dynamics confirmed that Na⁺-microenvironment could improve active-aggregation state and affect secondary structure of ΔLdcEt3. Therefore, Na⁺-microenvironment stabilizes ΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.