Preface for special issue on chemical bioproduction / 生物工程学报

Engineering efficient enzymes or microbial cell factories should help to establish green bio-manufacturing process for chemical overproduction. The rapid advances and development in synthetic biology, systems biology and enzymatic engineering accerleate the establishing feasbile bioprocess for chemical biosynthesis, including expanding the chemical kingdom and improving the productivity. To consolidate the latest advances in chemical biosynthesis and promote green bio-manufaturing, we organized a special issue on chemical bioproduction that including review or original research papers about enzymatic biosynthesis, cell factory, one-carbon based biorefinery and feasible strategies. These papers comprehensively discussed the latest advaces, the challenges as well as the possible solutions in chemical biomanufacturing.

Enzyme-instructed hybrid nanogel/nanofiber oligopeptide hydrogel for localized protein delivery

Enzyme-catalysis self-assembled oligopeptide hydrogel holds great interest in drug delivery, which has merits of biocompatibility, biodegradability and mild gelation conditions. However, its application for protein delivery is greatly limited by inevitable degradation of enzyme on the encapsulated proteins leading to loss of protein activity. Moreover, for the intracellularly acted proteins, cell membrane as a primary barrier hinders the transmembrane delivery of proteins. The internalized proteins also suffer from acidic and enzymatic degradation in endosomes and lysosomes. We herein develop a protease-manipulated hybrid nanogel/nanofiber hydrogel for localized delivery of intracellularly acted proteins. The embedded polymeric nanogels (CytoC/aNGs) preserve activity of cytochrome

Enzymatic synthesis of xylulose from formaldehyde / 生物工程学报

Xylulose as a metabolic intermediate is the precursor of rare sugars, and its unique pattern of biological activity plays an important role in the fields of food, health, medicine and so on. The aim of this study was to design a new pathway for xylulose synthesis from formaldehyde, which is one of the most simple and basic organic substrate. The pathway was comprised of 3 steps: (1) formaldehyde was converted to glycolaldehyde by benzoylformate decarboxylase mutant BFD-M3 (from Pseudomonas putida); (2) formaldehyde and glycolaldehyde were converted to dihydroxyacetone by BFD-M3 as well; (3) glycolaldehyde and dihydroxyacetone were converted to xylulose by transaldolase mutant TalB-F178Y (from Escherichia coli). By adding formaldehyde (5 g/L), BFD-M3 and TalB-F178Y in one pot, xylulose was produced at a conversion rate of 0.4%. Through optimizing the concentration of formaldehyde, the conversion rate of xylulose was increased to 4.6% (20 g/L formaldehyde), which is 11.5 folds higher than the initial value. In order to further improve the xylulose conversion rate, we employed Scaffold Self-Assembly technique to co-immobilize BFD-M3 and TalB-F178Y. Finally, the xylulose conversion rate reached 14.02%. This study provides a new scheme for the biosynthesis of rare sugars.

Progress in fungal polyketide biosynthesis / 生物工程学报

Fungal polyketides display complex structures and variously biological activities. Their biosynthetic pathways generally contain novel enzyme-catalyzed reactions. This review provides a summary of recent research advances in molecular mechanism of the biosynthesis of fungal polyketides including highly-reducing polyketide synthases (HR-PKSs), non-reducing polyketide synthases (NR-PKSs), as well as polyketide-nonribosomal peptide synthase (PKS-NRPSs) and reducingnon- reducing polyketide synthase (HR-NR PKSs) hybrids. The elucidation of biosynthetic mechanism of many fungal polyketides provides guidance on the discovery of new biosynthetic gene cluster of fungal polyketide natural products and compounds with novel structures as well as their analogue.

Carbon dioxide/methanol conversion cycle based on cascade enzymatic reactions supported on superparamagnetic nanoparticles

ABSTRACT The conversion of carbon dioxide into important industrial feedstock is a subject of growing interest in modern society. A possible way to achieve this goal is by carrying out the CO2/methanol cascade reaction, allowing the recycle of CO2 using either chemical catalysts or enzymes. Efficient and selective reactions can be performed by enzymes; however, due to their low stability, immobilization protocols are required to improve their performance. The cascade reaction to reduce carbon dioxide into methanol has been explored by the authors, using, sequentially, alcohol dehydrogenase (ADH), formaldehyde dehydrogenase (FalDH), and formate dehydrogenase (FDH), powered by NAD+/NADH and glutamate dehydrogenase (GDH) as the co-enzyme regenerating system. All the enzymes have been immobilized on functionalized magnetite nanoparticles, and their reactions investigated separately in order to establish the best performance conditions. Although the stepwise scheme led to only 2.3% yield of methanol per NADH; in a batch system under CO2 pressure, the combination of the four immobilized enzymes increased the methanol yield by 64 fold. The studies indicated a successful regeneration of NADH in situ, envisaging a real possibility of using immobilized enzymes to perform the cascade CO2-methanol reaction.

Bottleneck and Countermeasure on Biodiesel Production by Lipase-catalysis / 中国生物工程杂志

Biodiesel, a nontoxic,cleaning, renewable and biodegradable fuel, is expected as a substitute for conventional fossil diesel. There are three main approaches to produce biodiesel, alkali-catalysis processing, enzymatic-catalysis processing and supercritical processing. With the unique property of energy-saving and environment-friendly, enzymatic-catalysis appears a great potential for industrial application. The main bottleneck of this technology is high cost and low stability of the lipase, as well as the inactivation of lipase by methanol and so on. To settle the problem, several methods have been used including the fixed-bed bioreactor, enzyme immobilized processing, whole-cell biocatalyst, changing addition method of methanol, developing of novel acyl acceptor, enhancing methanol resistance of lipase. The main problems and the relative strategy research of the enzymatic-catalysis technology were sum up.

Enzymatic Synthesis of D-D4FC Using Intact Cells / 微生物学通报

D-D4FC (?-D-2′,3′-didehydro-2′,3′-dideoxy-5-fluorocytidine),a new anti-HIV drug,is on its PhaseⅡ clinical trials in America,France and Germany. Our lab has synthesized D-D4FC successfully using N-deoxyribosyltransferase from Lactobacillus helveticto catalyzing the ribose transfer from D4T (?-D-2′,3′-unsaturated thymidine) to 5-FC (5-fluorocytidine).The yield of D-D4FC reached 25%.We discovered the reaction could also be done by using intact cells.The yield could increase to 50% in 12.5 hours and more convenient to industrial continuous process.In this paper,the conditions including pH,buffer,substrates concentration,cells amount,reaction time and a possible catalytic mechanism were studied and discussed.