Green Chemical Engineering最新文献

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.

There are lots of biochemical reactions in the biosynthetic pathway without associated enzymes. Reactions predicted by retro-biosynthetic tools are not assigned gene sequences. Besides, non-natural reactions designed with novel functions also lack suitable enzymes. All these reactions can be categorized as orphan reactions. The absence of protein-encoding genes in these orphan reactions limits their direct experimental implementation. Computational tools have been developed to find candidate enzymes for these orphan reactions. Herein, we discuss recent advances in these computational tools, including reaction similarity-based methods for calculating the substructural similarity between orphan reactions and known enzymatic reactions; sequence-based tools combine metabolic knowledge base and phenotypic information with genomic, transcriptomic, and metabolomic data to mine appropriate enzymes for orphan reactions; and approaches based on the creation of enzyme variants for orphan reactions as enzyme engineering modifications and de novo design of enzymes. We believe that our review will greatly facilitate the design of microbial cell factories and contribute to the development of the biomanufacturing field.

Industrial pharmaceutical wastewater usually contains butyl acetate (BA) with a concentration of 1 wt%–7 wt%, and the traditional method for BA recovery is distillation with high energy consumption. Adsorption method is developed to recover BA with low concentration for the high efficiency and low energy consumption. Medium polar polyacrylate resins with macroporous structure of 233.1 nm and average particle size of about 526.5 μm are successfully synthesized by suspension polymerization and used for the BA adsorption and desorption. The maximum adsorption capacity reaches 171.1 mg g⁻¹ with relative standard deviation (RSD) value of 0.2%, which is more than twice the results in the literature. The BA desorption rate is 97.0% at 100 °C with RSD value of 0.4%, and the resins are beneficial to the reuse in the adsorption-desorption cycle. The adsorption thermodynamics and kinetics are investigated, and the BA adsorption is a spontaneous and endothermic process with the increase of disorder degree. This process is mainly contributed by physical absorption and agree well with Freundlich model and pseudo-first-order adsorption kinetic model. The adsorption method avoids boiling a large amount of wastewater and hopefully provides a novel alternative technology for the BA recovery.

Interactions of cellulose- and lignin-derived intermediates have been well documented during pyrolysis of lignocellulosic biomass. The reaction network for the interactions is rather complex, as cellulose-derived volatiles could interact/react with not only lignin-derived volatiles but also lignin-derived char and vice versa. To probe specifically the impacts of cellulose-derived volatiles on the lignin-derived char or the opposite, herein the sequential pyrolysis was performed by arranging cellulose in the upper bed with lignin in the lower bed or lignin above with cellulose below at 350 and 650 °C, respectively. The results indicated that the sequential pyrolysis of cellulose→lignin or lignin→cellulose at 350 °C induced increased char yield from formation of carbonaceous deposits via volatiles-char interactions. Compared with the lignin-derived volatiles, the cellulose-derived volatiles, especially aldehyde fractions, were more reactive towards the lignin-derived char at 350 °C, forming oxygen-rich lignin-derived char with a higher yield, an abundance of aliphatic structures and consequently lower thermal stability. In sequential pyrolysis of lignin→cellulose, more aromatics-rich species were deposited on cellulose-derived char, but the lignin-derived volatiles were less reactive for enhancing the char yield. At 650 °C, instead of polymerisation of the volatiles on the char, either the cellulose- or lignin-derived char catalyzed the cracking of the counterpart volatiles to remove the aliphatic functionalities, which made the char more aromatic and thermally more stable.