碳源对土曲霉中洛伐他汀生物合成的影响

通过摇瓶培养考察碳源种类及其初始水平对土曲霉次级代谢物洛伐他汀生物合成的影响。蔗糖和葡萄糖等快速利用碳源产洛伐他汀量较低,且易积累其直接前体monacolin J;淀粉和甘油等缓慢利用碳源有利于细胞生长和产物合成,其monacolin J积累相对较少,甘油为碳源时,可获得最高产物量(937.5±12.3)mg/L,乳糖不利于细胞生长导致较低的产物量。以淀粉为碳源时,其初始水平的增加可促进洛伐他汀的合成,碳质量分数为2%时对底物利用率较高,4%时最高产物量可达(875.4±23.1)mg/L,monacolin J则在2%—3%时积累较多,同时产生较多的2-甲基丁酸。     

复合诱变选育衣康酸高产菌株的研究

采用紫外线-LiCl、硫酸二乙酯(DES)复合诱变,经平板菌落筛选、摇瓶筛选以及连续传代稳定性考察,从土曲霉(Aspergillus terreus)2433出发菌株获得一株衣康酸高产突变株土曲霉At DES-11,其产酸量达到48.22 g/L,较出发菌株提高了156.08%;糖酸转化率为61.82%,较出发菌株提高了101.36%,且连续传代5次后,遗传性状仍较稳定,产酸量稳定在48 g/L左右,菌落及菌丝形态基本不变。     

FORMATION OF SULFATE CONJUGATES METABOLITES IN THE DEGRADATION OF PHENANTHRENE,ANTHRACENE, PYRENE AND BENZO[A]PYRENE BY THE ASCOMYCETE ASPERGILLUS TERREUS

Abstract

The metabolism of four PAHs (phenanthrene, anthracene, pyrene and benzo(a)pyrene) by an Aspergillus terreus strain, isolated from a polluted soil, was investigated in liquid submerged culture. The main metabolites identified by the HPLC-MS technique, after solvent extraction of the fermentation broth and mycelium, were aryl-sulfates and hydroxyl-aryl-sulfates. A metabolic pathway was identified involving in sequence: the hydroxylation by a monooxygenase of the PAHs, the conjugation with a sulfate ion, followed by a further hydroxylation to hydroxyl-aryl-sulfates compounds. PAHs degradation by A. terreus yielded a different number of metabolite isomers depending on the type of the parent PAH. The environmental fate and ecotoxicity of the metabolite 9-phenanthrenesulfate was also investigated by a respirometric test of ready biodegradability and by a Vibrio fischeri acute toxicity test respectively. This compound was easily degradable by microbial consortia derived from polluted soil and capable of thriving on phenanthrene as its sole carbon source. Moreover the sulfate conjugate resulted in 2 orders of magnitude less toxic than its precursors phenanthrene.     

土曲霉M11菌丝球对结晶紫的吸附脱色研究

研究了土曲霉M11菌丝球对水溶液中结晶紫染料的生物吸附作用,考察了菌丝球的死活及培养方式、培养温度、溶液盐度、培养时间、染料溶液初始pH值和接种量对结晶紫脱色率的影响。结果表明,土曲霉M11的菌丝球在35℃1、50 r.min-1振荡培养方式下脱色效果较好,灭活菌丝球脱色效果更好,其24 h内对结晶紫脱色率均达90%以上;培养温度和接种量对菌丝球脱色效果影响不大;在初始pH值为6时,脱色效果最好,对结晶紫脱色率达93%以上。另外,较低的盐浓度对菌丝球脱色效果有一定抑制作用,而较高的盐浓度对结晶紫脱色效果无明显影响。     

AstPT Catalyses both Reverse N1‐ and Regular C2 Prenylation of a Methylated Bisindolyl Benzoquinone

Prenylated bisindolyl benzoquinones exhibit interesting biological activities, such as antidiabetic or anti‐HIV activities. A number of these compounds, including asterriquinones, have been isolated from Aspergillus terreus. In this study, we identified two putative genes by genome mining, ATEG_09980 and ATEG_00702, which share high sequence similarity with the known bisindolyl benzoquinone prenyltransferase TdiB from Aspergillus nidulans. The coding sequences were cloned and overexpressed in E. coli. The overproduced recombinant proteins were purified to near homogeneity and used for enzyme assays with asterriquinone D in the presence of dimethylallyl diphosphate. HPLC analysis showed that product formation was only detected in enzyme assays with EAU29429 encoded by ATEG_09980, not in those with EAU39348 encoded by ATEG_00702. Product isolation and structure elucidation by NMR and MS analyses led to identification of N1‐reversely and C2‐regularly monoprenylated derivatives, as well as N1′,N1′′reversely, N1′‐reversely, C2′′‐regularly diprenylated derivatives. This proved that EAU29429 functions as an asterriquinone prenyltransferase (AstPT) and indicated the involvement of EAU29429 rather than EAU39348 in the biosynthesis of methylated asterriquinones. Furthermore, incubation of monoprenylated enzyme products with AstPT resulted in the formation of the diprenylated derivatives.     

Physical properties of polycaproamide/cationic dyeable poly(ethylene terephthalate) polyblended fibers

Polycaproamide (PCA) and cationic dyeable poly(ethylene terephthalate) (CDP) polymers were blended mechanically (in ratios of 75/25, 50/50, and 25/75) in a melt twin‐screw extruder to prepare three PCA/CDP polyblended materials. The blends of PCA and CDP were spun into fibers. The molar ratio of dimethyl 5‐sulfoisophthalate sodium salt for CDP was 2%. This study investigated the physical properties of PCA/CDP polyblended fibers with nuclear magnetic resonance, gel permeation chromatography, gas chromatography, potentiometer, differential scanning calorimetry (DSC), thermogravimetric analysis, scanning electron microscopy (SEM), extension stress–strain measurements, density gradient analysis, and rheometry. The experimental results of DSC proved that PCA and CDP formed an immiscible system. In an SEM image of a 50/50 PCA/CDP blend, the morphological aggregation of a larger size, from 3 to 5 μm in diameter, was observed. The rheological behavior of the PCA/CDP polyblended materials exhibited negative‐deviation blends, and the 50/50 blend of the PCA/CDP polyblended fibers showed a minimum tenacity value. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1710–1715, 2004     

Cocontinuous morphology in vinylidene fluoride based polymers/poly(ethylene oxide) blends

In this work, blends of three different vinylidene fluoride (VdF) based homopolymers and copolymers with poly(ethylene oxide) were investigated. We focused on the continuity domain and, more particularly, on the cocontinuous morphology of these systems. The melt‐mixed blends were characterized by different techniques. The morphology was identified through a selective extraction technique and was confirmed by scanning electron microscopy. Dynamic oscillatory shear measurements were performed with a constant stress rheometer in the linear viscoelastic domain in the whole composition range. Because of the high viscosities and long relaxation times of the VdF‐based polymers, the interfacial effects were hidden by the intrinsic behavior of the neat components. Nevertheless, the combination of the different techniques highlighted the similarity of the systems toward morphological development, whatever the VdF monomers. The experiments and theoretical analysis indicated that the rheological behavior dominated the interfacial effects in such systems with a large viscosity ratio and that it also dictated the boundaries of the continuity domain. The originality of this study came from the use of three different VdF‐based polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

洛伐他汀提取工艺研究

通过实验研究确定了从洛伐他汀发酵液中提取洛伐他汀的最佳工艺条件。实验表明乙醇作为溶剂时,其最佳工艺条件:浸提温度45℃,物料比5∶1(乙醇/mL∶菌丝/g),浸提时间4h,闭环温度80℃,闭环时间5h。本工艺简便、收率高,适用于工业化生产。