Production of a novel exopolysaccharide by Rahnella aquatilis

A bacterium Tomakomai B-1 that was isolated from the activated sludge of a treatment process for wastewater of the pulp industry was found to produce soluble and insoluble exopolysaccharides (EPSs) when grown aerobically in a medium containing sucrose as the sole carbon source. The sugar component of soluble EPSs consisted of rhamnose, mannose, galactose, glucose, mannuronic acid, galacturonic acid and glucuronic acid, and that of insoluble EPSs consisted of rhamnose, mannose, galactose, glucose, mannuronic acid and glucuronic acid. The concentrations of insoluble and soluble EPS were approximately 1.63 and 2.58 g/l, respectively, by Erlenmeyer flask culture at 20 degrees C for 3 d with a synthetic medium containing 1% sucrose, 0.05% CaCO(3), 0.05% MgSO(4), 0.1% K(2)HPO(4), 0.0001% Na(2)MoO(4), 0.01% urea, 1.07% MES and small amounts of trace metals. Tomakomai B-1 was identified as Rahnella aquatilis. To our knowledge the production of EPSs by R. Aquatilis is reported here for the first time.     

红酵母发酵生产胡萝卜素培养条件的优化研究

研究了不同的碳源、氮源和添加核黄素在红酵母Yh3发酵生产胡萝卜素过程中,对菌体生长和色素形成的影响,并用正交实验方法对碳源、氮源、pH值和通气量等培养条件进行了优化研究、结果表明,30g／L麦芽糖,10g／L酵母膏作为碳源和氮源,在pH60,摇床转速为150r／min,添加3×10－6mol／L的核黄素对色素形成较为有利,在此条件下发酵红酵母Yh3其生物量及色素产量最大值分别为9．8g／L和10．38mg／L。红酵母Yh3所产胡萝卜素主要成分为β-胡萝卜素。     

Production of two types of exopolysaccharide by Novosphingobium rosa

A bacterium, Ikeda-3, that was isolated from the wastewater of a winery was found to produce floating and precipitating exopolysaccharides (EPSs) when grown aerobically in a medium containing sucrose as the sole carbon source. The concentrations of floating and precipitating EPSs were approximately 2.7 g/l and 0.6 g/l, respectively, in a mini-jar fermentor after incubations of the bacterium at 15 degrees C for 5 d in a synthetic medium containing 1% sucrose, 0.01% CaCO3, 0.05% MgSO4, 0.05% K2HPO4, 0.0001% Na2MoO4, 0.05% peptone and 0.82% bicine. A component analysis of two types of EPS suggested that they represent a novel type of sphingan composed of glucose, rhamnose, mannose and mannuroic acid. Glucoronic acid, which is commonly found in sphingans, was absent. From physiological, biochemical and chemotaxonomic characterization, phylogenetic analysis and DNA-DNA relatedness, Ikeda-3 was identified as Novosphingobium rosa. To our knowledge the production of EPS by N. rosa is reported here for the first time.     

Production and composition of microbial fat from Rhodotorula glutinis

The fatty acid, sterol and hydrocarbon compositions of oil produced by a new strain of Rhodotorula glutinis isolated from soil and grown on molasses, were determined. The major constituent fatty acids were: palmitic (37%) oleic (47%) and linoleic (8%). The major sterols were campesterol (42%) and stigmasterol (27%) and the major hydrocarbons were n-C₂₃ (37%), iso-C₂₉ (30%) and n-C₂₁ (19%). Minor constituents in each class of lipids were also detected and estimated. The oil produced was 54% on a dry weight basis. The fatty acid composition was found to be close to that of palm oil.     

红酵母超高压诱变及其β-胡萝卜素发酵条件的初步研究

为了提高红酵母Rhodotorula glutinis NR06的β-胡萝卜素生产能力，利用超高压技术对其进行诱变处理，在300MPa处理10min时获得一突变株NR06-H39，其β-胡萝卜素产量达到9.64mg/L，比出发菌株NR06的6.30mg/L提高了53.02%，且遗传稳定性良好。分别研究了培养基碳、氮源等因素对该突变株胡萝卜素发酵的影响，获得了适宜的培养条件组合为培养基装量40ml/250ml、发酵液初始pH6.5、葡萄糖40g/L、（NH4）2SO45g/L、酵母膏5g/L、花生油0.4ml/L、番茄汁3ml/L和接种量8%，此时该突变株的胡萝卜素发酵产量可达12.42mg/L，比对照提高了28.84%。     

一株融合菌株G23产胞外多糖的流变学特性

融合菌株G23是由植物乳杆菌C88和发酵乳杆菌F6通过原生质体融合获得的菌株.采用动态流变仪,在不同多糖质量浓度、温度、pH值务件下测定融合菌株G23所产生的胞外多糖的流变学性质.所产胞外多糖溶液是典型的非牛顿流体,胞外多糖质量浓度的增大可提高溶液体系的黏度.在10～80℃的较大温度范围内黏度变化较小,在所测温度范围内溶液黏度基本保持不变.在不同pH值条件下,胞外多糖溶液均表现为剪切力作用下黏度迅速下降趋势.胞外多糖加入脱脂乳溶液中能够明显的增加脱脂乳的黏度,且溶液的黏度下降变慢.在试验的频率范围内,随着胞外多糖溶液质量浓度的增加,对应的交叉频率的值相应变大,胶体特征越明显.     

固定化酵母细胞转化肉桂酸生产L-苯丙氨酸

建立了一套较之传统方法更为准确的测定固定化细胞生产L-苯丙氨酸(L-phe)的新方法,采用高效液相色谱法(HPLC)测定反复冲洗凝胶所得冲洗液可以更准确地测定L-phe的生成,并采用新方法研究了固定化黏红酵母细胞的活力与稳定性。复合凝胶聚乙烯醇(PVA)+琼脂糖为最适载体,最佳质量浓度为PVA 120 g/L、琼脂糖10 g/L,反复冻融4次。此法得到的固定化细胞颗粒,机械强度良好,酶活保持时间长达200 h,L-苯丙氨酸产量高。通过流化床反应器测定其半衰期为100 h,200 h后总产量为44.58 mg/10 mL,固定化细胞无崩解现象。     

红酵母Y-5产类胡萝卜素培养基无机盐组分的优化

为提高红酵母菌株Y-5 发酵产类胡萝卜素的产量,对培养基中无机盐组分进行优化。采用Plackett-Burman试验设计从8 种无机盐中筛选出对提高类胡萝卜素产量具有显著效应的无机盐组分KH₂PO₄、MgSO₄ 和NaCl。通过Box-Behnken 设计及响应面分析确定其质量浓度为KH₂PO₄ 0.58g/L、MgSO₄ 0.49g/L、NaCl 0.28g/L 时,菌株的类胡萝卜素产量达到14.51mg/L,与未添加无机盐组分培养基相比,类胡萝卜素产量提高了25.09%。     

黏红酵母产油脂培养基的响应面优化

利用单因素试验和响应面设计相结合,对黏红酵母产油脂培养基进行了优化。单因素试验得到初步发酵培养基成分为葡萄糖、蛋白胨、KH2PO4。经响应面优化发现,当发酵培养基中葡萄糖含量为73.40g/L,蛋白胨含量为1.06 g/L,KH2PO4含量为3.56 g/L时,油脂产量的理论预测值可达到3.49 g/L,比优化前提高了13%。气相分析其油脂组成,多不饱和脂肪酸质量分数为26.97%。然后又对高产菌株的发酵特性进行研究,在10 d时,生物量和油脂产量达到最高,此时达到发酵终点,生物量为47.98 g/L(菌体湿重),油脂产量达到7.81 g/L。     

一株西藏灵菇嗜热链球菌产胞外多糖的流变学特性

以一株西藏灵菇嗜热链球菌为研究对象,系统地研究质量浓度、剪切速率、热处理、pH及盐离子对其所产胞外多糖流变学特性的影响。结果表明,该胞外多糖溶液具有良好的增稠性,质量浓度为8.6 mg/mL时其黏度可达到85.63mPa.s;多糖溶液呈高度假塑性,剪切稀释现象明显;热稳定性差,当温度由20℃升至100℃时,其黏度下降了74.4%,分别于60,80℃热处理150min,对多糖溶液黏度有不同程度的影响;多糖溶液黏度在酸性条件下相对稳定,但在中性和碱性条件下明显升高;并且随Ca2+浓度升高,多糖溶液黏度显著下降。     

光镊拉曼光谱技术结合响应面法优化红酵母产类胡萝卜素的发酵条件

拉曼光谱具有快速、实时、无损分析的特点,在生物学领域应用广泛。作者利用光镊拉曼光谱技术(LTRS)测定红酵母细胞中类胡萝卜素。采用Plackett-Burman法对影响红酵母发酵的相关因素进行评价,发现葡萄糖、蛋白胨、pH和温度对类胡萝卜素的产量影响显著。利用BoxBehnken设计和响应面分析法对影响类胡萝卜素产量的关键因素进行优化,获得的最优发酵条件为:葡萄糖42.86 g/L,蛋白胨5 g/L,酵母提取物5 g/L,KH2PO41 g/L,MgSO4。7H2O 0.5 g/L,pH 7.0,温度28.3℃,优化后类胡萝卜素产量较优化前提高了45%。     

N~+注入选育类胡萝卜素高产菌株及其固态发酵条件优化

为获得类胡萝卜素高产菌株,利用N+注入方法对黏性红圆酵母菌RM-1进行诱变处理,结果表明,当注入能量为10keV时,最适诱变注入剂量为2.0×1014ion/cm2,筛选所得突变株RM-21产类胡萝卜素的能力明显提高,较出发菌株增加了60.85%。传代结果表明,传代10次突变株RM-21遗传性状稳定,可作为工业生产菌种。以玉米粉和稻米为原料,对突变株RM-21固态发酵产类胡萝卜素进行条件优化研究,结果表明,当m玉米粉:m稻米=3:1,含水量75%时,固态发酵最适条件为:葡萄糖4.0g/L、NH4NO32.5g/L、初始pH6.0、接种量10%。在此基础上,对固态发酵产类胡萝卜素进行变温培养研究,结果表明,在96h的发酵时段中,0～84h温度控制在33℃,85～96h温度控制在28℃,类胡萝卜素产量达到7.04μg/g(以干基计),比恒温发酵提高了20.96%。     

离子注入选育高产类胡萝卜素红酵母

通过离子注入N+ 诱发基因突变 ,从而获得高产类胡萝卜素红酵母菌株RY 3 9,其出产率较出发菌株RY 3提高 76.2 % ;经复筛和传代实验表明 ,该高产菌株遗传性能较为稳定 ,3代平均类胡萝卜素产量提高了 74.0 %、质量浓度达 1 0 .9mg/L .     

真菌Simplicillium lanosoniveum胞外多糖合成条件的优化及其动力学分析

Simplicillium lanosoniveum（DT06）是一种能够合成特殊胞外多糖的半知菌类真菌。本文以真菌DT06为研究材料,采用BBD设计原则的响应面法优化其胞外多糖的合成工艺条件,并对其发酵动力学参数进行分析。在单因素实验的基础上,以胞外多糖得率为响应值,确定多糖合成的最优条件:初始p H4.87,葡萄糖40.65 g/L,蛋白胨10.38 g/L,温度30℃,转速140 r/min。优化后真菌DT06胞外多糖得率可达0.139 g/g,比优化前提高了32%。在此优化条件下,对DT06的发酵过程进行动力学分析,结果表明:DT06最大比生长速率μmax=0.156 h-1,其多糖合成与菌体生长部分偶联。与其它产多糖的真菌相比,DT06合成多糖的最大比合成速率较高达到0.066 h-1,但总的多糖得率却较低。碳平衡计算发现DT06还产生一种未知的中性含碳产物,其碳得率为0.129 g/g。上述实验为DT06多糖发酵过程的调控及其胞内代谢网络的优化提供了依据。      

Influences of pH and electrolyte on the rheological properties of aqueous solution of exopolysaccharide secreted by a deep-sea mesophilic bacterium

The effects of pH and electrolytes (NaCl and CaCl₂) on the viscosity, dynamic modulus (storage modulus G′ and loss modulus G″) and thixotropy of aqueous solution of new exopolysaccharide (SM-A87 EPS) secreted by a deep-sea mesophilic bacterium Wangia profunda SM-A87 were investigated. It was found that at pH 3–12 and the electrolyte concentration of 0.1–80 g/L, the SM-A87 EPS solution showed very weakly pH-dependent and salt-dependent rheological properties and dominant elastic behavior. These properties were considered to arise from the hyper-branched structure of the SM-A87 EPS molecules through the comparison of rheological properties of SM-A87 EPS solutions with those of partially hydrolyzed polyacrylamide ones at different electrolyte concentrations. Such good pH stability and salt resistance of the SM-A87 EPS solution indicate that SM-A87 EPS has great potential for application as food additive, thickener, stabilizer and enhanced oil recovery system. In the studied conditions, 2 g/L SM-A87 EPS solution showed positive thixotropy. The relative thixotropic recovery decreased with pH increasing and the electrolyte concentration decreasing.     

酵母生产类胡萝卜素发酵动力学研究

在5L发酵罐中,对酵母发酵生产类胡萝卜素的动力学特性进行了研究,得到了菌体生长、基质消耗和产物合成动力学模型。通过对实验数据的计算,模型的拟合结果和实验值能够较好吻合,说明该动力学模型能正确描述类胡萝卜素的发酵过程。     

Production of aldehyde oxidases by microorganisms and their enzymatic properties

In order to establish an efficient process to decompose environmentally toxic aldehydes, dioxygen-dependent aldehyde oxidase (ALOD) from microorganisms was first sought, and some bacteria and actinomycetes were found to produce the enzyme in their cells. Methylobacillus sp., Pseudomonas sp. and Streptomyces moderates were selected as the representative ALOD-producing strains and their enzymes were partially purified and characterized. The three ALODs could oxidize a wide range of aldehydes including formaldehyde, aliphatic aldehydes, and aromatic aldehydes, though their preferences differ depending on their producing strains. The other enzymatic properties were also determined with regard to their producing strains. Methylobacillus sp. ALOD had the most acidic optimum pH for its activity and stability and Pseudomonas sp. ALOD had the highest stability against heat treatment. Three native ALODs had molecular weights ranging from 140 to 148 kDa and were composed of three subunits of different sizes: large (85 to 88 kDa), medium-sized (37 to 39 kDa) and small (18 to 23 kDa).     

红酵母产生类胡萝卜素的研究注

研究了红酵母RY－98菌株产生类胡萝卜素的营养与环境条件,并对发酵过程生理现象的变化作了测试。结果表明：培养基组成、糖浓度和添加剂以及培养基初始pH值、通气量（摇瓶装量）与培养时间等,均对该菌细胞生物量和类胡萝卜素产量有影响,其中ZS添加剂的加入可以明显促进菌体类胡萝卜素的形成,这是本次研究的新发现,在初步优化的培养基组成（葡萄糖40g/L、玉米浆15g/L、（NH4）2SO42g/L、ZS添加剂1g/L）和培养条件下,菌体生物量与类胡萝卜素含量分别为27mg/mL和498.2μg/g,发酵液产色素能力为13.3mg/L。通过观测发酵过程生理现象的变化,认为该菌类胡萝卜素是菌体的次生代谢产物,主要形成于对数生长期的末期和稳定期。     

利用粘红酵母生产微生物油脂研究进展

粘红酵母是一种良好的产油微生物,其油脂可用来生产生物柴油。本文介绍了粘红酵母生产油脂的情况,包括其常用基本培养基,廉价工农业废弃物培养基,以及促进粘红酵母生长和产油的方法和培养条件,并对粘红酵母生产微生物油脂方面存在的问题和未来的发展方向进行了概述。