大豆异黄酮的微生物转化

大豆异黄酮是近年来发现的具有多种生物学活性的大豆营养成分。综述了微生物对大豆异黄酮的转化过程,对大豆异黄酮的生物利用和营养成分的影响,指出在富含大豆异黄酮类制品生产过程中合理利用微生物活动的重要意义和可能途径。     

微生物转化合成香兰素

香兰素是食品工艺中应用最广泛的香料之一。本文首先探讨了能够合成香兰素的微生物,其次讨论了可用于合成转化香兰素的底物,阐述了测定香兰素的方法,最后对生物合成香兰素的前景进行了展望。     

京尼平苷的微生物转化研究

本文利用高产β-葡萄糖苷酶菌种制备游离细胞和固定化细胞,在温和条件下可将京尼平苷转化为京尼平,转化率高达98%.通过条件优化,得到了最优转化条件:京尼平添加量1.5%,pH自然,摇瓶装量20%,28 ℃、150 rpm转化24 h.固定化细胞可连续使用4次.这种微生物转化法安全、高效,产品纯度高,是生产京尼平的一种新方法.     

微生物转化方法生产香草酸与香草醛的初步研究

从实验室保藏的菌种中筛选到一株黑曲霉（Aspergillus niger）SW-33,能够将1g/L的阿魏酸底物转化为0.23g/L的香草酸,相应的摩尔转化率为29.35％;流加四次底物阿魏酸后,产物浓度达到1.11g/L,相应的摩尔转化率为44.9％。为了提高产物浓度,对培养基和发酵条件进行优化,使得该菌株能够将1g/l的阿魏酸底物转化为0.46g/L的香草酸,相应的摩尔转化率为57.81％。提取得到的香草酸,经HPLC测定,纯度为85.9％;提取收率为75.2％。用含香草酸的转化液,或者用提取的结晶香草酸,加入朱红密孔菌（Prcnporus cinnabarnus）SW-0203发酵培养液,可得到转化产物香草醛。     

天然碱泥絮凝用微生物絮凝剂产生条件的研究

报道了内蒙天然碱碱泥絮凝用微生物絮凝剂适宜产生条件的研究结果。高糖低氮培养基有利于絮凝剂的产生。适宜摇床发酵条件为：初始PH值7．5－8．5,培养温度30℃,摇床转速180r/min,发酵60h;在摇床优化的培养条件的基础上进行5L罐放大试验,发酵周期缩短12h,絮凝活性提高了14．45％。     

微生物转化雄甾-4-烯-3，17-双酮的菌种筛选和转化条件的初步研究

雄甾-4-烯-3,17-双酮(简称4AD)是甾体药物的重要中间产物,其11α羟化产物可制成治疗心血管疾病的药物。通过对30株不同种属真菌转化4AD能力的筛选,获得球孢白僵菌(Beauveria bassiana)QY2A对4AD有高效C11α羟化能力,得到目标产物C11α-羟基雄甾-3,17-双酮(简称11α-OH-4AD)。另对该菌株的转化条件进行优化,结果表明:初始pH值6.0,温度28℃,转速180r/min,转化时间60h,助溶剂甲醇终浓度和底物浓度分别为2.5%和2.5g/L时,11α-OH-4AD的转化率为65%,比未优化的转化率提高了51.2%。     

Actinobacillus succinogenes 130Z厌氧发酵产丁二酸条件初步研究

对Actinobacillus succinogenes130Z厌氧发酵产丁二酸的培养条件进行了初步研究。研究了不同有机氮源,不同碳、氮源浓度配比、CO2供体、培养温度,培养基起始pH值对菌株生长和产酸的影响,并在5 L发酵罐中进行了放大试验。结果表明最佳培养基配方为(g/L):葡萄糖10,酵母膏5,NaHCO310,Na2HPO40.3,NaH2PO4.2H2O 9.6,K2HPO43,MgCl20.2,MnCl20.2,NaCl 0.1;pH7.0。在最佳条件下,血清瓶37℃培养24 h,丁二酸产量达到8.3 g/L,在5 L发酵罐中培养,葡萄糖质量浓度分别为10和100 g/L时,丁二酸产量分别达到8.2和45.6 g/L,收率分别为80%和65%。     

木糖醇微生物转化的研究

一、引言 木糖醇是一种被广泛用于国防、医药、食品和化学等工业的五碳糖醇。木糖醇也是一种具有营养价值的甜味剂,由于它的代谢不需胰岛素,可作为糖尿病人的食糖代用品。另外木糖醇还可以作为防龋食品。目前国内外生产木糖醇的方法是化学法,即由农业纤维废料如玉米芯和甘蔗渣等经酸水解和提     

新型羟基化酶基因的克隆及其洛伐他汀转化的应用

无锡他汀由洛伐他汀经拟无枝酸菌Amycolatopsis sp. CGMCC1149羟基化而来。为获得该转化过程中的关键酶——羟基化酶,运用简并PCR和SEFA PCR技术,从Amycolatopsis sp. CGMCC1149中克隆获得长度为1 212 bp的新型羟基化酶基因,并实现其在大肠杆菌中表达。BLAST序列分析表明该基因属于细胞色素P450基因超家族,并可编码一个含403氨基酸的蛋白,其分子量为44.8 kDa。二级结构预测结果表明：该蛋白包含有氧结合区、离子对结合区和血红素结合区等P450典型功能区。同时文中利用NADH、铁氧还蛋白和铁氧还蛋白还原酶建立了体外酶催化功能验证系统,首次实现无锡他汀转化底物洛伐他汀的体外羟基化。该结果为具有我国独立知识产权的无锡他汀大规模制备奠定了基础。     

微生物除臭剂发酵工艺条件优化及硫素转化的研究

利用酵母菌、乳酸菌、醋酸菌三种可食性微生物复配发酵制备微生物除臭剂,研究微生物复配比、发酵时间、发酵温度、接种量四个因素对H_2S去除率的影响。以单因素实验为基础,利用Box-Behnken响应面法优化最佳发酵条件,进一步研究硫元素转化及含量动态变化。结果表明酵母菌、乳酸菌、醋酸菌质量比为1∶2∶2时,各因素对H_2S去除率的影响由高到低依次为发酵温度发酵时间接种量,最优发酵条件为发酵时间48. 5 h、发酵温度30℃、接种量12. 75%,H_2S的去除率可达到71. 84%;实验组与对照组的硫元素转化及含量动态变化相比,实验组的SO_4~(2-)含量显著较高(P0. 05),H_2S释放量显著较低(P0. 05)说明该微生物除臭剂可以调节硫元素转化,有效抑制H_2S产生。     

Enhanced lovastatin production by solid state fermentation ofMonascus ruber

The purpose of this study was to optimize the solid state cultivation ofMonascus ruber on sterile rice. A single-level-multiple-factor and a single-factor-multiple-level experimental design were employed to determine the optimal medium constituents and to optimize carbon and nitrogen source concentrations for lovastatin production. Simultaneous quantitative analyses of the β-hydroxyacid form and β-hydroxylactone for of lovastatin were performed by the high performance liquid chromatography (HPLC) method with a UV photodiode-array (PDA) detector. The total lovastatin yield (4≈6 mg/g, average of five repeats) was achieved by adding soybean powder, glycerol, sodium nitrate, and acetic acid at optimal composition of the medium increased by almost 2 times the yield observed prior to optimization. The experimental results also indicated that the β-hydroxylactone form of lovastatin (LFL) and the β-hydroxyacid form of lovastatin (AFL) simultaneously existed in solid state cultures ofMonascus ruber, while the latter was the dominant form in the middle-late stage of continued fermentation. These results indicate that optimized culture conditions can be used for industrial production of lovastatin to obtain high yields.     

一株高产洛伐他汀红曲霉的筛选与液态发酵条件优化

【背景】洛伐他汀(lovastatin)是红曲霉的次生代谢产物,是重要的临床用降血脂药物。在液态发酵条件下,红曲霉的洛伐他汀产量较低,难以满足工业化生产的要求。【目的】筛选获得一株高产洛伐他汀的红曲霉株,并通过优化液态发酵条件提高洛伐他汀的产量。【方法】从红曲米中筛选获得一株高产洛伐他汀的红曲霉株,依据形态学特征、生理生化特性及18S rRNA基因序列分析对分离菌株进行鉴定;通过响应面法对其产洛伐他汀的液态发酵条件进行优化。【结果】获得一株产洛伐他汀的紫红曲霉(Monascus purpureus M4),该菌在甘油57.80g/L、酵母浸粉5.52 g/L、接种量为6.90%条件下,洛伐他汀产量(173.60 mg/L)较优化前提高了4.8倍。【结论】菌株M4产洛伐他汀最优液态发酵条件的建立,为洛伐他汀的大规模生产及该菌株的工业化应用提供了技术支撑。     

雷帕霉素发酵条件研究

研究了不同发酵条件对雷帕霉素产量的影响。结果显示在最优条件下,进行了100L发酵罐的发酵试验,发酵190-200h雷帕霉素的产量为1200mg／L,产量较优化前提高一倍,达到了工业化生产的要求,为进一步放大生产奠定了基础。     

Juvenile toxicity assessment of open-acid lovastatin in rats

BACKGROUND: Lovastatin, an inhibitor of 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase, reduces de novo cholesterol biosynthesis primarily in the liver. Since cholesterol is a major component of brain myelin and peak periods of brain myelination occurs after birth, this study was designed to encompass this period in rats and evaluate the potential neurotoxic effects. METHODS: The pharmacologically active, open‐acid form of lovastatin was administered to groups of 50 Sprague–Dawley rats per sex subcutaneously once daily at dose levels of 0 (vehicle), 2.5, 5, or 10 mg/kg/day beginning on postnatal day 4 and continuing until termination on postnatal day 41 to 51. Physical signs and body weights were monitored during the study. Animals were assessed in a battery of behavioral tests, and at termination a set of animals were examined for gross and histological changes. RESULTS: There were no test article‐related deaths, physical signs, or effects on preweaning and postweaning body weights during the study. In the behavior tests there were no test article‐related effects in the passive avoidance, auditory startle habituation, open‐field motor activity, or FOB. No test article‐related postmortem findings were observed, including brain weights and histomorphology of brain, spinal cord, eye, optic nerve, or peripheral nerve. CONCLUSION: Based on these results, the no‐effect level for general and neurobehavioral toxicity in neonatal rats was ≥10 mg/kg/day for open‐acid lovastatin. Birth Defects Res (Part B) 92:314–322, 2011. © 2011 Wiley‐Liss, Inc.     

弹性蛋白酶产生菌发酵条件的研究

针对不同碳氮源及无机盐对芽胞杆菌EA915产弹性蛋白酶的影响进行了研究,结果表明,最适碳源为葡萄糖,最适氮源为酵母膏,无机盐硫酸镁,硫酸亚铁对弹性蛋白酶的产生有促进作用.初步研究了产酶条件,在初始pH为7.0、摇瓶装液量20mL/250mL ,37℃下发酵52h,酶活最高,达到160 U/mL.     

粗壮假丝酵母(Candida valida 20231)产脂肪酶发酵条件的研究

对粗壮假丝酵母(Candida valida 20231)产脂肪酶所需的培养基成分和发酵条件进行了优化。结果表明,粗壮假丝酵母在接种后3 h即进入对数期,18 h后转入稳定期,66 h后进入衰退期;发酵36 h达到最大酶活,至72 h仍然无明显下降趋势。最适合的培养基成分为:4.0%大豆粉,2.0%菜籽油,0.3%葡萄糖,0.3%NH_4NO_3,1.2%K_2HPO_4,0.42%NaH_2PO_4,0.4%MgSO_4·7H_2O。使用优化的培养基,最佳产酶的条件为:装液量80 mL(250 mL摇瓶),初始pH 6,接种量为2.0%,种子菌龄为12 h。在最佳产酶条件下,脂肪酶活力达到32.6 U/mL。     

Oxidative state in idiophase links reactive oxygen species (ROS) and lovastatin biosynthesis: Differences and similarities in submerged- and solid-state fermentations

The present work was focused on finding a relationship between reactive oxygen species (ROS) and lovastatin biosynthesis (secondary metabolism) in Aspergillus terreus. In addition, an effort was made to find differences in accumulation and control of ROS in submerged (SmF) and solid-state fermentation (SSF), which could help explain higher metabolite production in the latter. sod1 expression, ROS content, and redox balance kinetics were measured during SmF and SSF. Results showed that A. terreus sod1 gene (oxidative stress defence enzyme) was intensely expressed during rapid growth phase (trophophase) of lovastatin fermentations. This high expression decreased abruptly, just before the onset of production (idiophase). However, ROS measurements detected high concentrations only in idiophase, suggesting a link between ROS and lovastatin biosynthesis. Apparently sod1 down regulation promotes the rise of ROS during idiophase. This oxidative state in idiophase was further supported by a high redox balance observed in trophophase that changed to a low value in idiophase (around six-fold lower). The patterns of ROS accumulation, sod1 expression, and redox balance behaviour were similar in SmF and SSF. However, sod1 expression and ROS concentration (ten-fold), were higher in SmF. Our results indicate a link between ROS and lovastatin biosynthesis. Also, showed differences of physiology in SSF that yield lower but more steady ROS concentrations, which could be associated to higher lovastatin production.