EVALUATION OF UV DOSE IN FLOW-THROUGH REACTORS FOR FRESH APPLE JUICE AND CIDER

High absorptivity and turbidity interfere with the UV disinfection of apple cider. Three different configurations of flow-through UV reactors were evaluated to overcome this interference. Two approaches were employed: use of an extremely thin film UV reactor and increasing the turbulence within a UV reactor. Multiple-lamp UV reactors including the thin-film laminar flow “CiderSure” (8 lamps) and turbulent flow “Aquionics” (12 lamps) and annular single-lamp “UltraDynamics” reactor were studied. UV disinfection performance in laminar and turbulent flow reactors was compared by evaluation of UV dose delivery. UV fluence rate (irradiance) distribution was calculated using the multiple point source summation method. E. coli K12 was used as a target bacterium in a bioassay, and the log reduction per one pass was determined for each UV reactor. Finally, the UV decimal reduction dose (D₁₀) was calculated by dividing the average UV fluence by log bacterial reduction per pass. Variations of the UV decimal dose were observed with various designs of UV systems. The least inactivation of E. coli K12 but the highest UV decimal reduction dose, ranging from 90 to 150 mJ/cm², was observed in the Aquionics UV reactor in apple cider with apparent absorption coefficient (a) of 5.7 mm^?1. The lower value of UV decimal reduction dose of 7.3–7.8 mJ/cm² was required for inactivation of E. coli K12 in malate buffer and apple juice in the annular single-lamp UltraDynamics reactor. However, the decimal reduction dose for E. coli K12 in apple cider was significantly higher, about 20.4 mJ/cm². Similar UV decimal reduction doses from 25.1 to 18.8 mJ/cm² for inactivation of E. coli K12 were observed in the thin-film ‘CiderSure’ UV reactor in apple cider with identical absorption coefficient. Mathematical modeling of UV irradiance can improve the evaluation of UV dose delivery and distribution within the reactors.     

Photocatalytic inactivation of Escherischia coli: Effect of concentration of TiO2 and microorganism, nature, and intensity of UV irradiation

The efficiency of photocatalytic disinfection, used to inactivate Escherischia coli K12 under different physico-chemical parameters, was examined. The photocatalyst chosen was the semiconductor TiO₂ degussa P25 and the irradiation was produced by an HPK 125 lamp. The effect of titania concentration was investigated using two E. coli concentrations. The photocatalyst concentration ranged from 0.1 to 2.5 g/L. The evolution of E. coli inactivation as function of time was discussed depending on the E. coli and TiO₂ concentrations. The optimal concentration of the photocatalyst, 0.25 g/L, is lower than that necessary to absorb all photons and to degrade the organic compounds. Some hypotheses are presented to explain this behaviour. The effect of the different domains of UV light (UVA, UVB, and UVC) was also studied and modification of the light irradiation intensity is discussed. No bacteria photolysis was obtained with UVA but the use UVC had, on the contrary, a detrimental effect on bacteria survival. The addition of titania at a low concentration, 0.25 g/L, improved the inactivation of E. coli in the presence of UVA and UVB, but a detrimental effect was observed under UVC. The disinfection efficiency increases as a function of light intensity, whatever the photocatalytic conditions (different TiO₂ concentrations and different UV domains). No bacterial growth was observed after disinfection, whether the system contained titania or not.     

Surface Mechanical Properties of the Spore Adhesive of the Green Alga Ulva

The mechanical properties of the adhesive produced by spores of the green, marine, fouling alga Ulva linza are reported. Atomic force microscopy studies were performed and nanoindentation data were analyzed using a model for an asymmetric indenter. Freshly secreted adhesive is characterized by multiple layers. We found that the modulus of the outer ∼600-nm thick layer was about 0.2 ± 0.1 MPa, whereas the modulus of the inner layer was about 3 ± 1 MPa. Older adhesive showed the formation of a “crust” of harder material with a yield strength of ∼20 MPa at a loading rate of 2.5 × 10^-6 N · s^-1. Mechanical properties under tension are also described, and extension profiles that showed either constant or nonlinear force changes with tip-sample separation were observed. Models for both kinds of behavior are described. The work of adhesion between poly-dimethylsiloxane (PDMS)-coated AFM tips and the adhesive was determined to be less than 1.5 mJ · m^-2.     

OPTIMIZATION OF PHOTOCATALYTIC PROCESS PARAMETERS FOR THE DEGRADATION OF 2,4,6-TRICHLOROPHENOL IN AQUEOUS SOLUTIONS

In the present study, the photocatalytic degradation of 2,4,6-trichlorophenol (2,4,6-TCP) was carried out in a batch reactor under UV light in aqueous solution for 5 h using titania P-25 (surface area 50 m²/g) as a photocatalyst and sodium hypochlorite as an oxidant. Variables studied include catalyst dose (0.25-1.25 g/L), pH (2-6), and concentration of the oxidant (3.06 × 10^-6M-15.3 × 10^-6M). The rate of degradation was studied in terms of changes in concentration of the pollutant and reduction in chemical oxygen demand. The optimal values of operational parameters leading to 2,4,6-TCP abatement were obtained by using response surface methodology. The percent degradation and COD reduction of 2,4,6-TCP was found to increase with increases in the catalyst dose up to the dose of 1.1 g/L, pH in the range of 4-4.5, and oxidant concentration of 9.95 × 10^-6M.     

BIOSTABILITY IN AMMONIUM-LIMITED CULTURES OF Escherichia coli B/r

The possibility of multiple steady-states and their prediction in chemical reactors was established by the pioneering work of Amundson and colleagues. This paper reports on a heretofore unknown type of multiple steady-state in a chemostat (CFSTR) with a pure culture of E. coli B/r growing under ammonium limitation. Two steady-states at dilution rate (0.91 hr^-1) near the maximum growth rate (0.94 hr^-1) result in residual concentrations of ammonium ion of ca. 40 mg/L and 1.5 mg/L. Dilution rate is the reciprocal of holding time. Models of single cells of E. coli can be used to predict the existence of such multiple steady-states. Ammonium uptake and assimilation both can occur via parallel pathways. The presence of the parallel pathways admits the possibility of this type of multiplicity. The parameters of the ammonium transport mechanism are crucial in allowing multiple steady-states. The model predicts specific growth rates higher than observed in batch culture for the chemostat low residual ammonium steady-state. Data consistent with the prediction of increased maximum specific growth rates is presented.     

Use of coaxial photocatalytic reactor (CAPHORE) in the TiO2 photo-assisted treatment of mixed E. coli and Bacillus sp. and bacterial community present in wastewater

This paper reports the photocatalytic disinfection of water contaminated by a mixture of Escherichia coli and Bacillus sp. as well as that of wastewater containing a larger microbial community. The photocatalytic reactions were carried out in a coaxial photocatalytic reactor called CAPHORE, using TiO₂ P-25 of Degussa. E. coli is more sensitive than Bacillus sp. to photocatalytic treatment. Bacterial inactivation was dependent on organic matter and dissolved oxygen (DO) concentration.

Of the bacterial community present in partially treated wastewater, E. coli appears to be more sensitive to the treatment than Enterococcus sp., coliforms (other than E. coli), and Gram-negative (other than coliforms). After photocatalytic treatment, no bacterial recovery of previous groups was observed for 24 h in the dark. However a very low bacterial inactivation rate was observed for the whole bacterial population present in wastewater and detected by non-selective media. The effective disinfection time (EDT), the time necessary for total inactivation of bacteria without re-growth in a subsequent dark period referenced at 24 h (or 48 h), was reached only for Enterococcus sp., and coliform groups. EDT₂₄ was not reached for the whole population.     

The role of potassium ferrate(VI) in the inactivation of Escherichia coli and in the reduction of COD for water remediation

The use of potassium ferrate(VI) as an alternative water remediation chemical has been studied and is reported in this paper. The water remediation performance of potassium ferrate(VI) was evaluated in comparison with sodium hypochlorite, ferric sulphate (FS) and aluminium sulphate (AS). The effects of the dosages of ferrate(VI), hypochlorite and FS/AS and solution pH were investigated. A model water with Escherichia coli (E. coli) number concentration of 3.2×10⁸/100 ml was used to examine the comparative disinfection performance and a real sewage sample was used to assess the comparative coagulation performance. The study demonstrated that the potassium ferrate(VI) performed superior to sodium hypochlorite in the inactivation of E. coli; less ferrate(VI) dose and contact time were required to achieve the same E. coli killing efficiency, the disinfection performance was less affected by the solution pH, and the disinfection rate of the ferrate(VI) was faster than that with sodium hypochlorite. In sewage treatment, ferrate(VI) performed superiorly as a oxidant and a coagulant; it can reduce 30% more COD, and kill 3 log more bacteria in comparison with AS and FS at a similar or even smaller dose.     

微孔聚丙烯膜表面壳聚糖季铵盐的共价修饰及其抗菌性能

为了赋予微孔聚丙烯膜（MPPM）抗菌能力,增强其抗污染性能,本文通过丙烯酸的光引发接枝聚合、壳聚糖与聚丙烯酸的酰胺化反应、壳聚糖胺基与2,3-环氧丙基三甲基氯化铵的开环加成,成功地在MPPM膜表面通过共价修饰技术构建了壳聚糖季铵盐修饰层。构建过程通过FTIR、XPS和荧光素二钠盐染色分析得到了证实。静态水接触角和吸水量实验结果表明,制得的修饰膜具有优异的表面润湿性和吸水性,吸水量可达11.23mg/cm²,为未修饰MPPM的1123倍。以大肠杆菌和金黄色葡萄球菌为代表,采用平板活菌计数法考察了修饰膜的抗菌性能和抗菌稳定性。研究结果表明,修饰膜具有良好的抗菌活性,对大肠杆菌的抗菌率可达98%,对金黄色葡萄球菌的抗菌率可达100%,且抗菌效果稳定,在水处理领域具有潜在的应用前景。     

Photoelectrocatalytic and photocatalytic disinfection of E. coli suspensions by titanium dioxide

This paper reports studies of the photoelectrocatalytic and photocatalytic disinfection of E. coli suspensions by titanium dioxide in a sparged photoelectrochemical reactor.

Two types of titanium dioxide electrode have been used. ‘Thermal’ electrodes were made by oxidation of titanium metal mesh; ‘sol–gel’ electrodes were made by depositing and then heating a layer of titania gel on titanium mesh. Cyclic voltammetry was used to carry out an initial characterisation and optimisation of both electrode types. The best ‘thermal electrodes’—i.e. those with the highest photocurrents—were prepared by heating titanium mesh at 700 °C in air. For sol–gel derived electrodes, optimum performance was obtained by heating at 600 °C. These electrodes were then used, in a gas sparged reactor, to disinfect E. coli suspensions with an initial concentration of 10⁷ colony forming units (cfu) ml⁻¹. Films prepared by the oxidation of titanium metal were shown to be superior to sol–gel derived films. Direct experimental comparison demonstrates that the photoelectrochemical system is more efficient than photocatalytic disinfection effected by slurries of Degussa P25 titanium dioxide.

Since in practical systems the TiO₂ would be exposed to a variety of species additional to those that are targeted, we also examined the effects of H₂PO₄⁻ and HCO₃⁻ ions on the measured disinfection rates. Phosphate addition poisons both the electrode and particulate-slurry systems and is only partially reversible. By contrast, although bicarbonate addition affects all three systems, the effects are reversible.     

Effect of pH, inorganic ions, organic matter and H2O2 on E. coli K12 photocatalytic inactivation by TiO2: Implications in solar water disinfection

The effect of different chemical parameters on photocatalytic inactivation of E. coli K12 is discussed. Illumination was produced by a solar lamp and suspended TiO₂ P-25 Degussa was used as catalyst. Modifications of initial pH between 4.0 and 9.0 do not affect the inactivation rate in the absence or presence of the catalyst. Addition of H₂O₂ affects positively the E. coli inactivation rate of both photolytic (only light) and photocatalytic (light plus TiO₂) disinfection processes. Addition of some inorganic ions (0.2 mmol/l) like HCO₃⁻, HPO₄²⁻, Cl⁻, NO₃⁻ and SO₄²⁻ to the suspension affects the sensitivity of bacteria to sunlight in the presence and in absence of TiO₂. Addition of HCO₃⁻ and HPO₄²⁻ resulted in a meaningful decrease in photocatalytic bactericidal effect while it was noted a weak influence of Cl⁻, SO₄²⁻ and NO₃⁻. The effect of counter ion (Na⁺ and K⁺) is not negligible and can modify the photocatalytic process as the anions. Bacteria inactivation was affected even at low concentrations (0.2 mmol/l) of SO₄²⁻ and HCO₃⁻, but the same concentration does not affect the resorcinol photodegradation, suggesting that disinfection is more sensitive to the presence of natural anions than photocatalytic degradation of organic compounds. The presence of organic substances naturally present in water like dihydroxybenzenes isomers shows a negative effect on photocatalytic disinfection. The effect of a mixture of chemical substances on photocatalytic disinfection was also studied by adding to the bacterial suspension nutrient broth, phosphate buffer and tap water.     

Thermoelectric characterization of NaxMx/2Ti1−x/2O2 (M=Co, Ni and Fe) polycrystalline materials

Layered -titanate materials, Na_xM_x/2Ti_1−x/2O₂ (M=Co, Ni and Fe, x=0.2–0.4), were synthesized by flux reactions, and electrical properties of polycrystalline products were measured at 300–800 °C. After sintering at 1250 °C in Ar, all products show n-type thermoelectric behavior. The values of both d.c. conductivity and Seebeck coefficient of polycrystalline Na_0.4Ni_0.2Ti_0.8O₂ were ca. 7×10³ S/m and ca. −193 μV/K around 700 °C, respectively. The measured thermal conductivity of layered -titanate materials has lower value than conductive oxide materials. It was ca. 1.5 Wm⁻¹ K⁻¹ at 800 °C. The estimated thermoelectric figure-of-merit, Z, of Na_0.4Ni_0.2Ti_0.8O₂ and Na_0.4Co_0.2Ti_0.8O₂ was about 1.9×10⁻⁴ and 1.2×10⁻⁴ K⁻¹ around 700 °C, respectively.     

Characterization of four diol dehydrogenases for enantioselective synthesis of chiral vicinal diols

Enantiopure vicinal diols are important building blocks used in the synthesis of fine chemicals and pharmaceutical compounds. Diol dehydrogenase(DDH) mediated stereoselective oxidation of racemic vicinal is an efficient way to prepare enantiopure vicinal diols. In this study, four new bacterial DDHs(AnDDH from Anoxybacillus sp. P3 H1 B, HcDDH from Hazenella coriacea, GzDDH from Geobacillus zalihae and LwDDH from Leptotrichia wadei) were mined from the GenBank database and expressed in E. coli T7...     

PHYSICAL CHARACTERISTICS AND DRYING RATE OF ECHINACEA ROOT

Echinacea angustifolia or the purple coneflower is an important medicinal plant that boosts the immune system. It is believed that the active ingredients are predominantly located in the root. Physical characteristics and drying rates of the root of E. angustifolia from a farm in Saskatchewan, Canada were studied. Root consisted of a main (central) root and secondary root branches. Cleaned roots exhibited wide variations in mass ranging from 15 to 95 g. The central root diameter varied from 9 to 20 mm with an average of 14 mm. The average initial moisture content of the fresh root was 57% (wb). The specific densities of the fresh and completely dried root were 1040 and 1370 kg/m³, respectively; and the corresponding bulk densities of loosely piled roots were 305 and 410 kg/m³. Roots were dried in a convection oven at temperatures of 23, 30, 40, 50, 60 and 70°C. Equations for estimating drying rates, drying constants, and equilibrium moisture content were developed. Increased drying temperatures reduced echinacosides but did not affect alkamides 1 and 2 which are known to be also responsible for medicinal value of E. Angustifolia.     

盖子环替换及定点突变提高菜豆环氧化物水解酶对邻甲基苯基缩水甘油醚的催化性能

菜豆环氧化物水解酶1和2（PvEH1、PvEH2）能够动力学拆分外消旋邻甲基苯基缩水甘油醚（rac-oMGE）,从而保留(R)-oMGE。基于对PvEH1和PvEH2结构的同源模拟和分析,发现二者分子中的盖子环差异较大,故本文选择盖子环作为研究目标。经融合聚合酶链式反应（FPCR）,获得了PvEH2的盖子环区域被PvEH1对应区域替换的杂合酶Pv2Pv1。用全细胞酶E. coli/pv2pv1催化rac-oMGE,当(S)-oMGE刚好水解完全时,产物(S)-3-邻甲苯基-1,2-丙二醇（(S)-oTPD）的ee_p由PvEH2的58.3%提高至75.5%。为进一步提高酶的性质,在Pv2Pv1中选取11个氨基酸位点进行丙氨酸(A)突变,获得最优突变子E. coli/pv2pv1^K176A,活性为E. coli/pv2pv1（4.2U/g）的2.1倍,且当S构型的底物刚好完全水解时,(S)-oTPD的ee_p进一步提高为80.3%。分子对接分析发现,盖子环替换和K176位点突变为A,均使(R)-oMGE环氧环中的C_α更易受到酶中D101位点的攻击。利用E. coli/pv2pv1^K176A催化150mmol/L rac-oMGE水解制备(R)-oMGE（ee_s＞99%）和(S)-oTPD（ee_p=80.4%）,二者的产率Y_S和Y_P分别为32.7%和60.1%,时空产率STY_S和STY_P为1.6g/(L·h)和3.3g/(L·h)。本实验为改善EH的催化性质提供了一种有效策略。     

Dilute solution properties of carboxymethylchitins in high ionic-strength solvent

The hydrodynamic characteristics in aqueous solution at ionic strength I=0.2  of carboxymethylchitins of different degrees of chemical substitution have been determined. Experimental values varied over the following ranges: the translational diffusion coefficient (at 25.0°C), 1.1<10⁷×D<2.9 cm² s⁻¹; the sedimentation coefficient, 2.4<s<5.0 S; the Gralen coefficient (sedimentation concentration-dependence parameter), 130<k_s<680 mL g⁻¹; the intrinsic viscosity, 130<[η]<550 mL g⁻¹. Combination of s with D using the Svedberg equation yielded ‘sedimentation–diffusion' molecular weights in the range 40 000<M<240 000 g mol⁻¹. The corresponding Mark–Houwink–Kuhn–Sakurada (MHKS) relationships between the molecular weight and s, D and [η] were: [η]=5.58×10⁻³ M^0.94; D=1.87×10⁻⁴ M^−0.60; s=4.10×10⁻¹⁵ M^0.39. The equilibrium rigidity and hydrodynamic diameter of the carboxymethylchitin polymer chain is also investigated on the basis of wormlike coil theory without excluded volume effects. The significance of the Gralen k_s values for these substances is discussed.     

Absence of E. coli regrowth after Fe and TiO2 solar photoassisted disinfection of water in CPC solar photoreactor

Field disinfection of water in a large solar compound parabolic collector (CPC) photoreactor (35–70 l) was conducted at 35 °C by different photocatalytic processes: sunlight/TiO₂, sunlight/TiO₂/Fe³⁺, sunlight/Fe³⁺/H₂O₂ and compared to the control experiment of direct sunlight alone. Experiments were carried out using a CPC and natural water spiked with E. coli K 12. Under these conditions, total disinfection by bare sunlight irradiation was not reached after 5 h of treatment; and bacterial recovery was observed during the subsequent 24 h in the dark.

The addition of TiO₂, TiO₂/Fe³⁺ or Fe³⁺/H₂O₂ to the water accelerates the bactericidal action of sunlight, leading to total disinfection by solar-photocatalysis. No bacterial regrowth was observed during 24 h after stopping sunlight exposure. For some samples, the decrease of bacteria continues in the dark. A “residual disinfection effect” was observed for these samples before reaching the total inactivation. The effective disinfection time (EDT₂₄), defined as the treatment time required to prevent any bacterial regrowth during the subsequent 24 h in the dark, after stopping the phototreatment, was reached in the presence but not in the absence of different photocatalytic systems. EDT₂₄ was 2 h 30 min, 2 h and 1 h 30 min for sunlight/TiO₂, sunlight/TiO₂/Fe³⁺ and sunlight/Fe³⁺/H₂O₂ systems, respectively. The post irradiation events observed when the phototreated water is poured into an optimal growth medium are also discussed.     

High-quality, oriented and mesostructured organosilica monolith as a potential UV sensor

We synthesized high-quality and oriented periodic mesoporous organosilica (PMO) monoliths through a solvent evaporation process using a wide range of mole ratios of the components: 0.17–0.56 1,2-bis(triethoxysilyl)ethane (BTSE): 0.2 cetyltrimethylammonium chloride (CTACl): 0–1.8 × 10⁻³ HCl: 0–80 EtOH: 5–400 H₂O. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images indicated that the mesoporous channels within the monolith samples were oriented parallel to the flat external surface of the PMO monolith and possessed a hexagonal symmetry lattice (p6mm). The PMO monolith synthesized from a reactant composition of 0.35 BTSE: 0.2 CTACl: 1.8 × 10⁻⁶ HCl: 10 EtOH: 10 H₂O had a pore diameter, pore volume, and surface area – obtained from an N₂ sorption isotherm – of 25.0 Å, 0.96 cm³ g⁻¹ and 1231 m² g⁻¹, respectively. After calcination at 280 °C for 2 h in N₂ flow, the PMO monolith retained monolith-shape and mesostructure. Pore diameter and surface area of the calcined PMO monolith sample were 19.8 Å, 0.53 cm³ g⁻¹ and 1368 m² g⁻¹, respectively. We performed ²⁹Si and ¹³C CP MAS NMR spectroscopy experiments to confirm the presence of Si–C bonding within the framework of the PMO monoliths. We investigated the thermal stability of the PMO monoliths through thermogravimetric analysis (TGA). In addition, rare-earth ions (Eu³⁺, Tb³⁺ and Tm³⁺) were doped into the monoliths. Optical properties of those Eu³⁺, Tb³⁺ and Tm³⁺-doped PMO monoliths were investigated by photoluminescence (PL) spectra to evaluate their potential applicability as UV sensors.     

用CuO/A12O3/堇青石催化剂选择性催化还原脱硝的实验和动力学研究

The CuO/γ-Al2O3/cordierite catalyst, after being sulfated by sulfur dioxide (SO2) at 673 K, exhibits high activities for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH3) at 573-723 K. The intrinsic kinetics of SCR of NO with NH3 over CuO/γ-Al2O3/cordierite catalyst has been measured in a fixed-bed reactor in the absence of internal and external diffusions. The experimental results show that the reaction rate can be quantified by a first-order expression with activation energy of 94.01 kJ&#8226;mol&#61485;1 and the corresponding pre-exponential factor of 3.39×108 cm3&#8226;g&#61485;1&#8226;s&#61485;1 when NH3 is excessive. However, when NH3 is not enough, an Eley-Rideal kinetic model based on experimental data is derived with Ea of 105.79 kJ&#8226;mol&#61485;1, the corresponding A of 2.94×109 cm3&#8226;g&#61485;1&#8226;s&#61485;1, heat of adsorption ΔHads of 87.90 kJ&#8226;mol&#61485;1 and the corresponding Aads of 9.24 cm3&#8226;mol&#61485;1. The intrinsic kinetic model obtained was incorporated in a 3D mathematical model of monolithic reactor, and the agreement of the prediction with experimental data indicates that the present kinetic model is adequate for the reactor design and engineering scale-up.     

Efficient production of cyclic adenosine monophosphate from adenosine triphosphate by the N-terminal half of adenylate cyclase from Escherichia coli

In this study, we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP). First, adenylate cyclase from Escherichia coli MG1655 (EAC) and Bordetella Pertussis (BAC) were expressed in E. coli BL21 (DE3) and comparatively analyzed for their activities. As a result, EAC from E. coli MG1655 exhibited a higher activity. However, amount of EAC were obtained in an insoluble form. Therefore, we expressed the first 446 amino acids of EAC (EAC446) to avoid the inclusion body. The effects of induction temperature, incubation time, and incubation pH were further evaluated to improve the expression of EAC446. Subsequently, the reaction process for the production of cAMP with ATP as a starting material was investigated. As none of cAMP was detected in the whole-cell based biocatalytic process, the reaction catalyzed by the crude enzyme was determined for cAMP production. What's more, the reaction temperature, reaction pH, metal ion additives and substrate concentration was optimized, and the maximum cAMP production of 18.45 g·L^-1 was achieved with a yield of 95.4% after bioconversion of 6 h.     

重组大肠杆菌表达17β-羟基类固醇脱氢酶全细胞催化合成宝丹酮的研究

宝丹酮作为一种重要的蛋白同化雄性激素类固醇,具有提升肌肉质量和耐力的功能。宝丹酮的传统合成方法是以1,4-雄烯二酮（ADD）为底物通过化学法合成,但过程复杂、污染严重。17β-羟基类固醇脱氢酶（17β-HSD）可催化甾体化合物C-17位点的氧化还原反应,实现ADD和宝丹酮的相互转化。本研究通过基因序列同源性分析,筛选到6种不同来源的17β-HSD基因并对其在大肠杆菌中进行异源表达。利用不同重组菌转化ADD合成宝丹酮,结果表明重组菌BL21/pET28a-HSDPy的ADD转化率最高,因此选择BL21/pET28a-HSDPy进行进一步研究。鉴定了重组菌的酶学性质并优化其全细胞转化条件。结果表明在生物量为36 g·L^-1、底物浓度为5.40 g·L^-1条件下,经过两次补料,获得了3.66 g·L^-1宝丹酮,比优化前提高了4.1倍。而且在生物转化过程中未检测到副产物。为生物合成宝丹酮提供了可能。