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Sugar alcohols are the prominent alternatives of sugars in food, medical, and health industries. The ruthenium supported on multiwalled carbon nanotubes (Ru/MWCNTs) catalysts were prepared based on the Ru valence regulation strategy and applied for selective sugar hydrogenation to prepare various sugar alcohols including xylitol, arabinitol, sorbitol, mannitol, and galactitol for the first time, with high selectivity (>99.0%) and yield (>98.0%) under mild conditions (≤110 °C, 3.0 MPa H2 pressure). The hydrogenation reaction of xylose was further optimized and under mild conditions (100 °C, 3.0 MPa H2 pressure, and 500 rpm), which were lower than ever reported for high efficient synthesis of xylitol, 99.8% xylose conversion and 99.0% xylitol yield were achieved after 120 min of reaction.

A lipase from Sporisorium reilianum SRZ2 (SRL) with 73% amino acid sequence identity to Candida antarctica lipase B (CALB) was cloned and overexpressed in Pichia pastoris. The recombinant SRL showed a preference for short-chain p-nitrophenyl esters. It achieved maximum activity at pH 8.0 and 65°C for p-nitrophenyl hexanoate (C6) with Km and kcat/Km values of 0.14 mmol·L−1 and 1712 min−1 · mmol · L−1 at 30°C, respectively. SRL displayed excellent thermostability and pH stability, retaining more than 79% of its initial activity after incubation at 60°C for 72 h and 75% at pH 3 to 11 for 72 h. It also maintained most of its activity in the presence of inhibitors and detergents except sodium dodecyl sulfate, and it tolerated organic solvents. SRL was covalently immobilized and successfully used for ethyl hexanoate synthesis in cyclohexane or in a solvent-free system with a high conversion yield (> 95%). Furthermore, high conversion yield was also achieved for the synthesis of various short-chain flavor esters when high substrate concentrations of 2 mol · L−1 were applied. This study indicated that a CALB-type lipase from S. reilianum SRZ2 showed great potential in organic ester synthesis.

The Candida Antarctica lipase B (CALB) was embedded in the metal-organic framework, zeolitic imidazolate framework-8 (ZIF-8) and applied in the enzymatic synthesis of L-ascorbic acid palmitate (ASP) for the first time. The obtained CALB@ZIF-8 achieved the enzyme loading of 80 mg/g with 11.3 U/g (dry weight) unit activity, 59.8% activity recovery and 92.7% immobilization yield. Under the optimal condition, ASP was synthesized with over 75.9% conversion of L-ascorbic acid in a 10-batch reaction. Continuous synthesis of ASP was subsequently performed in a packed bed bioreactor with an outstanding average space-time yield of 58.1 g L-1 h-1 , which was higher than ever reported continuous ASP biosynthesis reactions. This article is protected by copyright. All rights reserved.

Candida antarctica lipase B (CALB) is a robust biocatalyst for production of chemicals. In this study, an engineered lipase B (CALB-I189K) was covalently immobilized onto a glutaraldehyde activated amino resin (ESR-3) and used for the preparation of chiral moxifloxacin precursor though enzymatic resolution of cis-(±)-dimethyl 1-acetylpiperidine-2,3-dicarboxylate (cis-(±)-1). The immobilization conditions were optimized, and the immobilized CALB-I189K exhibited improved thermal stability, with a half-life of 247.5 h at 30 °C. It enables the resolution of 100 g L–1 cis-(±)-1 for 50 cycles in a stirred tank reactor, with an average productivity of 49.6 g L–1 h–1. The resolution reaction was also performed in a recirculating packed bed reactor (RPBR) in a semicontinuous mode, and the average productivity reached 59.4 g L–1 h–1 under the optimal operating condition. Moreover, the RPBR bioconversion system has high operational stability and conserved over 85.7% of the initial conversion capacity after 50 cycles...

Asymmetric synthesis of chiral epichlorohydrin (ECH) from 1,3-dichloro-2-propanol (1,3-DCP) using halohydrin dehalogenases (HHDHs) is of great value due to the 100% theoretical yield and high enantioselectivity. The vital problem in the asymmetric synthesis is to prepare optically pure ECH. In this study, key amino acid residues located at halide ion channels of HheC (P175S/W249P) (HheCPS) were modified to regulate the kinetic parameters. HheCPS I81W, F86N and V94R were constructed with the corresponding halide ion channels destroyed. The catalytically efficiencies (kcat/Km) of the three mutants exhibited 0.38-, 0.23- and 0.23-fold decrease toward (S)-ECH and the reverse reaction was significantly inhibited. As the results, (S)-ECH was synthesized with >99% enantiomeric excess (e.e.) and 63.42%, 67.08% and 57.01% yields, respectively, under 20 mM 1,3-DCP as substrate. To our knowledge, this is the first investigation of the molecule kinetic modification of HHDHs and also the first report for the biosynthesis of optically pure (S)-ECH from 1,3-DCP using HHDHs.

Ezetimibe is a top-selling hypolipidemic drug for the treatment of cardiovascular diseases. Biosynthesis of (4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one ((S)-ET-5) using carbonyl reductase has shown advantages including high catalytic efficiency, excellent stereoselectivity, mild reaction conditions, and environmental friendness, and was considered as the key step for ezetimibe production. The regeneration efficiency of the cofactor, nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) is one of the main restricted factor. Recombinant Escherichia coli strain (smCR125) coexpressing carbonyl reductase (CR125) and glucose dehydrogenase were successfully constructed and applied for the production of (S)-ET-5 for the first time. Without extra addition of the coenzyme NADPH, the yield of 99.8% and the enantiomeric excess (e.e.) of 99.9% were achieved under ET-4 concentration of 200 g/L. Using a substrate fed-batch strategy, under the optimal conditions, the substrate ET-4 concentration was increased to 250 g/L with the yield of 98.9% and the e.e. of 99.9% after 12 hr reaction. The space-time yield of 494.5 g L-1 d-1 and the space-time yield per gram biocatalyst of 24.7 g L-1 d-1 g-1 DCW were achieved, which were higher than ever reported for the biosynthesis of the ezetimibe intermediate.

Asymmetric synthesis of chiral epichlorohydrin (ECH) from 1,3-dichloro-2-propanol (1,3-DCP) using halohydrin dehalogenase (HHDH) is of great value due to the 100% theoretical yield and high enantioselectivity. In this study, HheC (P175S/W249P) was immobilized on an A502Ps resin and used for the preparation of (S)-ECH. In aqueous system, the immobilized HheC catalyzed the biosynthesis of (S)-ECH with 83.78% yield and 92.53% enantiomeric excess (ee) at 1,3-DCP concentration of 20 mM. The non-aqueous system was further developed using water saturated ethyl acetate as solvent and reaction phase. The non-aqueous bioconversion system showed higher enantioselectivity (>98% ee) toward (S)-ECH production with modest conversion (52.34%) compared with ever reported aqueous reactions. Batch reactions were performed in a packed-bed bioreactor for 45 batches in aqueous phase and 24 batches in non-aqueous phase. The present work demonstrated the potential of immobilized HheC (P175S/W249P) in aqueous and non-aqueous phase biosynthesis of chiral ECH.

In this study, a carbonyl reductase RtSCR9 from Rhodosporidium toruloides was engineered to improve its activity for asymmetric reduction of N,N-dimethyl-3-keto-3-(2-Thienyl)-1-keto propanamine (DMAK) to (S)-3-(dimethylamino)-1-(2-Thienyl)-1-propanol (S-DMAA). Error-prone polymerase chain reaction (epPCR) combined with megaprimer PCR of whole plasmid (MEGAWHOP) method and site saturation mutagenesis was used to construct random mutant libraries. The positive mutant was screened by measuring the decrease in the absorbance of NADPH at 340 nm and high performance liquid chromatography (HPLC). The best Mut-A89N/F154Y was obtained and compared with wild type RtSCR9, the Vmax and kcat of Mut-A89N/F154Y were enhanced by 2.08 and 3.86-fold, respectively, while the Km decreased by 2.36-fold. The reduction of DMAK by Mut-A89N/F154Y afforded S-DMAA with a yield of 91.2% and enantiomeric excess of 99.9% at 2 M DMAK, which was highest ever reported. This mutant could be a potential candidate for the upscale production of S-DMAA.

To develop a method for fast replacement of promoters to improve protein production. A method (entitled retreat to advance or “ReToAd”), which includes a deleting PCR and a touchdown PCR, was validated by replacing seven IPTG-inducible promoters with enhanced green fluorescent protein (eGFP). The seven promoters were fully recovered by sequencing only 30 clones. The activity of E. coli harboring ω-transaminase (ω-TA) was increased from 112 U/mg cells (T7 promoter) to 147 U/mg cells (Trc promoter) by combining ReToAd and screening experiments. After screening a library comprising glutamate dehydrogenase (GDH) expressed by different promoters, the activity of E. coli cell harboring Trc-promoter-expressed GDH was ~31-fold higher than that of T7-promoter-expressed GDH. The “ReToAd” for in situ rapid replacement of promoters was developed and optimized, and one round of “ReToAd” can be completed within 3 days.

Candida antarctica lipase B (CALB) is a versatile and robust lipase with high activity and enantioselectivity in the resolution of alcohols and amines. Poor specific activity toward carboxylic esters that are branched or substituted in close proximity to the carboxyl group limits the application of CALB. In this study, a semi-rational engineering approach was successfully applied to tailor CALB for efficient synthesis of the moxifloxacin chiral intermediate through enzymatic resolution of cis-(±)-dimethyl 1-acetylpiperidine-2,3-dicarboxylate. The combinatorial active-site saturation test was performed on CALB and two key residue sites, 189 and 190, were identified in the determination of hydrolytic activity. The specific activity and catalytic efficiency (kcat/Km) of the best variant mut-I189K were increased by 286- and 193-fold, respectively, without impacting its enantioselectivity. With 0.1 g L−1 of purified mut-I189K loading, 1 M substrate was asymmetrically hydrolyzed with 49.9% conversion within 5 h, resulting in a space–time yield of 583.8 g L−1 d−1. These results demonstrated that mut-I189K is a competitive biocatalyst for large-scale preparation of the moxifloxacin chiral intermediate.

(4 S )-3-[(5 S )-5-(4-Fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one (( S )-ET-5) is an important chiral intermediate in the synthesis of chiral side chain of ezetimibe. Recombinant Escherichia coli expressing carbonyl reductase (CBR) was successfully constructed in this study. The total E. coli biomass and the specific activity of recombinant CBR in 5 L fermenter culture were 10.9 g DCW L −1 and 14900.3 U g −1 DCW, respectively. The dual-enzyme coupled biocatalytic process in an aqueous-organic biphasic solvent system was first constructed using p -xylene as the optimal organic phase under optimized reaction conditions, and 150 g L −1 (4 S )-3-[5-(4-fluorophenyl)-1,5-dioxophentyl]-4-phenyl-1,3-oxazolidin-2-one (ET-4) was successfully converted to ( S )-ET-5 with a conversion of 99.1% and diastereomeric excess of 99% after 24-h, which are the highest values reported to date for the production of ( S )-ET-5.

Alcohol dehydrogenases (ADHs), which belong to the oxidoreductase superfamily, catalyze the interconversion between alcohols and aldehydes or ketones with high stereoselectivity under mild conditions. ADHs are widely employed as biocatalysts for the dynamic kinetic resolution of racemic substrates and for the preparation of enantiomerically pure chemicals. This review provides an overview of biotechnological applications for ADHs in the production of chiral pharmaceuticals and fine chemicals.

A rapid, sensitive, selective and accurate ultra high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the quantitation of prucalopride in rat plasma using carbamazepine as an internal standard (IS). Separation was achieved on a Waters ACQUITY UHPLC(®) HSS C18 column (2.1mm×50mm, 1.8μm) column with a gradient mobile phase consisting of acetonitrile-water (containing 0.1% formic acid) as mobile phase at a flow rate of 0.2mL/min. Prucalopride and IS were monitored using positive electrospray triple quadrupole mass spectrometer (Waters Xevo TQD) via multiple reaction monitoring (MRM) mode. The monitored transitions were set at m/z 367.99→195.89 and m/z 236.97→194.04 for prucalopride and IS, respectively. The achieved lower limit of quantitation was 0.1ng/mL. The validated method had an excellent linearity in the range of 0.1-100ng/mL (r>0.996). The intra- and inter-day precisions were both≤7.8% for prucalopride and IS, and the average intra- and inter-day accuracies ranged from -3.0% to 8.5%. Extraction recoveries at three levels QC concentrations were in the range of 90.0-110.0% for prucalopride and 99.6% for IS. Matrix effects were found to be acceptable. The validated assay was successfully applied to a pharmacokinetic study of prucalopride following oral administration of 0.25, 0.5, 1.0mg/kg to female and male rats respectively.

tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is an important chiral intermediate for the synthesis of rosuvastatin. The biotechnological production of (3R,5S)-CDHH is catalyzed from tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH) by a carbonyl reductase, and this synthetic pathway is becoming a primary route for (3R,5S)-CDHH production due to its high enantioselectivity, mild reaction conditions, low cost, process safety, and environmental friendship. However, the requirement of the pyridine nucleotide cofactors, reduced nicotinamide adenine dinucleotide (NADH) or reduced nicotinamide adenine dinucleotide phosphate (NADPH) limits its economic flexibility. In the present study, a recombinant Escherichia coli strain harboring carbonyl reductase R9M and glucose dehydrogenase (GDH) was constructed with high carbonyl reduction activity and cofactor regeneration efficiency. The recombinant E. coli cells were applied for the efficient production of (3R,5S)-CDHH with a substrate conversion of 98.8%, a yield of 95.6% and an enantiomeric excess (e.e.) of >99.0% under 350 g/L of (S)-CHOH after 12 hr reaction. A substrate fed-batch strategy was further employed to increase the substrate concentration to 400 g/L resulting in an enhanced product yield to 98.5% after 12 hr reaction in a 1 L bioreactor. Meanwhile, the space-time yield was 1,182.3 g L-1 day-1 , which was the highest value ever reported by a coupled system of carbonyl reductase and glucose dehydrogenase.

tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate [(3R,5S)-CDHH] is the key chiral intermediate to synthesize the side chain of the lipid-lowering drug rosuvastatin. Carbonyl reductases showed excellent activity for the biosynthesis of (3R,5S)-CDHH. The requirement of cofactor NADH/NADPH leads to high cost for the industrial application of carbonyl reductases. In this study, a self-sufficient biocatalyst based on carbonyl reductase and NADP+ co-immobilization strategy was developed on an amino resin carrier LX-1000HAA (SCR-NADP+@LX-1000HAA). The self-sufficient biocatalyst achieved in situ cofactor regeneration and showed the activity recovery of 77.93% and the specific activity of 70.45 U/g. Asymmetric synthesis of (3R,5S)-CDHH using SCR-NADP+@LX-1000HAA showed high enantioselectivity (> 99% e.e.) and yield (98.54%). Batch reactions were performed for ten cycles without extra addition of NADP+, and the total yield of (3R,5S)-CDHH achieved at 10.56 g/g biocatalyst. The present work demonstrated the potential of the self-sufficient biocatalyst for the asymmetric biosynthesis of rosuvastatin intermediate.

The creation of an R-selective ω-amine transaminase (ω-ATA) as biocatalyst is crucial for the asymmetric amination of prochiral ketones to produce sitagliptin intermediates because rare ω-ATAs are R-selective in nature and most of them suffer from poor stability and low activity toward bulky prochiral ketones. Here, the gene of an R-selective ω-ATA was cloned from Arthrobacter cumminsii ZJUT212 (AcATA) and expressed in Escherichia coli. The best variants (M1 + M122H and M1+T134 G) were obtained using a semi-rational protein design after screening. These variants not only exhibited improved activity and substrate affinity but also enhanced stability in aqueous phase containing 20 % dimethyl sulfoxide. The conversion of asymmetric amination on 50 g/L pro-sitagliptin ketone PTfpB (1-[1-piperidinyl]-4-[2,4,5-trifluorophenyl]-1,3-butanedione) achieved 92 %, with an extremely high e.e. of >99 %, using 2 gDCW/L E. coli cells harboring M1 + M122H as biocatalyst. In the kilogram-scale experiment, approximately 40 kg of (R)-APTfpB (e.e. >99 %) was produced within 30 h when 50 kg PTfpB was used as the substrate. Furthermore, the space–time yield reached ≈32 g/(L·d).

A novel and rapid microwave extraction and ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of 25 bioactive constituents (including two new constituents) in Fructus Alpinia oxyphylla. The optimized conditions of the microwave extraction was a microwave power of 300 W, extraction temperature of 80°C, solvent-to-solid ratio of 30 mL/g and extraction time of 8 min. Separation was achieved on a Waters ACQUITY UPLC(®) HSS C18 column (2.1 mm× 50 mm, 1.8 μm) using gradient elution with a mobile phase consisting of acetonitrile and 1 mM ammonium acetate at a flow rate of 0.2 mL/min. This is the first report of the simultaneous determination of 25 bioactive constituents in Fructus Alpinia oxyphylla by ultra high performance liquid chromatography with tandem mass spectrometry. The method was validated with good linearity, acceptable precision and accuracy. The validated method was successfully applied to determine the contents of 25 bioactive constituents in Fructus Alpinia oxyphylla from different sources and the analysis results were classified by hierarchical cluster analysis, which indicated the effect of different cultivation regions on the contents of constituents. This study provides powerful and practical guidance in the quality control of Alpinia oxyphylla and lays the foundation for further research of Alpinia oxyphylla.

Two guanidine bases were used as organocatalysts for the synthesis of cyclic monothiocarbonates via the coupling reaction of carbonyl sulfide (COS) and epoxides. The systems proved to be efficient single-component, metal-free catalysts for the reaction of simple (propylene oxide, 1,3-butene oxide) or activated epoxides (epichlorohydrin, glycidyl phenyl ether) with COS under solvent-free and mild reaction conditions to selectively afford the corresponding cyclic monothiocarbonates. The yield of this reaction is generally high, thereby providing ready means for pure product isolation.

tert -Butyl (3 R ,5 S )-6-chloro-3,5-dihydroxyhexanoate ((3 R ,5 S )-CDHH) is the key intermediate for synthesis of atorvastatin and rosuvastatin. Carbonyl reductase exhibits excellent activity toward tert -butyl ( S )-6-chloro-5-hydroxy-3-oxohexanoate (( S )-CHOH) to synthesize (3 R ,5 S )-CDHH. In this study, a whole cell biosynthesis reaction system to produce (3 R ,5 S )-CDHH was constructed in organic solvents. A solution of 10% ( v/v ) Tween-80 was introduced to the reaction system as a co-solvent, which greatly enhanced biotransformation process, giving 98.9% yield, >99% ee and 1.8-fold higher space time yield in 5 h bioconversion of 1 M ( S )-CHOH, compared with 98.7% yield and >99% ee in 9 h bioconversion of a purely aqueous reaction system. Moreover, a water-octanol biphasic reaction system was built and 20% of octanol was added as reservoir of substrate resulting in 98% yield, >99% ee and 4.08 mmol L −1 h −1 g −1 (wet cell weight) space time yield. This study paved a way for the whole cell biosynthesis of (3 R ,5 S )-CDHH in mono and biphasic media.

tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is a key intermediate of atorvastatin and rosuvastatin synthesis. Carbonyl reductase RtSCR9 from Rhodosporidium toruloides exhibited excellent activity toward tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH). For the activity of RtSCR9 to be improved, random mutagenesis and site-saturation mutagenesis were performed. Three positive mutants were obtained (mut-Gln95Asp, mut-Ile144Lys, and mut-Phe156Gln). These mutants exhibited 1.94-, 3.03-, and 1.61-fold and 1.93-, 3.15-, and 1.97-fold improvement in the specific activity and kcat/Km, respectively. Asymmetric reduction of (S)-CHOH by mut-Ile144Lys coupled with glucose dehydrogenase was conducted. The yield and enantiomeric excess of (3R,5S)-CDHH reached 98 and 99%, respectively, after 8 h bioconversion in a single batch reaction with 1 M (S)-CHOH, and the space-time yield reached 542.83 mmol L–1 h–1 g–1 wet cell weight. This study presents a new carbonyl reductase for efficient sy...

Two parallel hybrid processes (Biological filter Coagulation/Ultrafiltration(BCUF) and Coagulation/Ultrafiltration(CUF)) for treating slightly polluted surface water were carried out in this experiment. In the process of BCUF, transverse flow water-dropping aerated biological filter was used as a primary pretreatment, and coagulation was used as the subsequent pretreatment of Ultrafiltration(UF). In the CUF process, coagulation was the unique pretreatment of UF. Turbidity was removed nearly completely in both two hybrid processes, and in the BCUF, effective ammonia nitrogen removal (87.1%) was also achieved mainly through the biological nitrification carried out in the biological filter, however, only 25.6% removal of ammonia nitrogen was achieved in the process of CUF. The removal rates of CODMn, TOC, DOC, UV254, AOC and BDOC were 55.2%, 87.8%, 71.0%, 61.1%, 91.4% and 89.3% respectively in the process of BCUF, which were much higher than that in the process of CUF. The biological pretreatment could improve the biological stability significantly and relieve the membrane fouling which made the transmembrane pressure (TMP) arising velocity lower. The pretreatment of biological filter and coagulation could remove the organic molecules in the range of 5000-500Da. Results showed the water-dropping aerated biological filter was fit for the pretreatment of UF.

This paper focuses on the mechanisms of the biological activated carbon (BAC) process. It is found that the bioregeneration hypothesis of desorption by exoenzymatic reactions is the common basis for some previous mechanisms. But by considering properties of the enzymes involved in the biodegradation pathway of phenols and aromatic hydrocarbons and distribution of exoenzymes in carbon pores, it is suggested that the hypothesis is not valid in most circumstances. A series of tests has been made in which phenol was used as the testing pollutant. The BAC column test was performed to investigate the changes in carbon adsorption capacity during operation. Properties of biological activity in BAC were measured by a Warburg respirometer. A comparative test between the BAC bed reactor and biological aerated filters was also made. All test results were contradictory to the mechanisms based on the bioregeneration hypothesis and supported the authors' suggestion that the mechanism of the BAC process is basically a simple combination of biodegradation and carbon adsorption. It is suggested that some specially designed biological aerated filter (BAF), instead of a BAC bed reactor, may be used in advanced wastewater treatment.

Hematite, a type of inorganic-sorptive medium, was used for the removal of U (VI) from aqueous solutions. Variables of the batch experiments including solution pH, contact time, initial concentration, temperature, calcium and magnesium ions were studied. The results indicated that the adsorption capacities are strongly affected by the solution pH, contact time and initial concentration. A higher pH favors higher U (VI) removal. The adsorption was also affected by temperature and calcium and magnesium ions, but the effect is very weak. The maximum adsorption capacity (q(m)) only increased from 3.36 mgg(-1) to 3.54 mgg(-1) when the temperature was increased from 293 K to 318 K. A two-stage kinetic behavior was observed in the adsorption of uranium (VI): very rapid initial adsorption in a few minutes, followed by a long period of slower uptake. It was found that an increase in temperature resulted in a higher uranium (VI) loading per unit weight of the sorbent. The adsorption of uranium by hematite had good efficiency, and the equilibrium time of adsorbing uranium (VI) was about 6h. The isothermal data were fitted with both Langmuir and Freundlich equations, but the data fitted the former better than the latter. The pseudo-first-order kinetic model, pseudo-second-order kinetic model and intraparticle diffusion model were used to describe the kinetic data, but the pseudo-second-order kinetic model was the best. The thermodynamic parameter Delta G(0) were calculated, the negative Delta G(0) values of uranium (VI) at different temperatures confirmed the adsorption processes were spontaneous.