重组大肠杆菌厌氧发酵产丁二酸培养条件的优化

采用Plackett-Burman设计法(Plackett-Burman,PB)对影响Escherichia coli NZN111(sfcA)厌氧发酵生产丁二酸的11个因子进行了筛选。结果表明,影响该菌厌氧发酵生产丁二酸的主要影响因子为乙酸钠、MgCO3、接种量、诱导剂IPTG加入时间和发酵周期。在此基础上采用响应曲面法(Response Surface Methodology,RSM)对这5个因子的影响进行了研究,得出多元二次回归方程拟合的5种因素与丁二酸产量间的函数关系,并根据优化结果与实验验证,当初始葡萄糖浓度为22 g/L,乙酸钠1 g/L,MgCO317 g/L,接种量10%,IPTG初始时加入,发酵周期76 h时,丁二酸产量从原始发酵培养条件下的11.84 g/L提高到15.64 g/L,收率从53.8%提高到71.1%。     

啤酒废酵母酶解液作为有机氮源厌氧发酵制备丁二酸的研究

确定了以啤酒废酵母为原料,酵母酶解液中α-氨基氮含量为考察指标的蜗牛酶酶解破壁条件;并以啤酒废酵母酶解液为有机氮源,厌氧发酵制备丁二酸。结果表明蜗牛酶破壁效果最好,其最佳反应条件为蜗牛酶用量10mg/g干物质,pH6.5,40℃水浴,反应16h,酵母酶解液中α-氨基氮含量为0.504g/100mL;当发酵培养基中葡萄糖浓度为50g/L,啤酒废酵母酶解液作为有机氮源时,菌株Actinobacillus succinogenes NJ113可以产34.6g/L丁二酸,收率69%,和以酵母膏为有机氮源厌氧发酵制备丁二酸(丁二酸浓度为35.1g/L,收率70.2%)比较,产量相近,成本较低。     

红酵母生物合成类胡萝卜素的培养条件优化

采用红酵母(Rhodotorula mucilaginosa)发酵生产类胡萝卜素,对其培养基及培养条件进行了研究。得到2组适合红酵母生长的培养基,其中葡萄糖组各组分最佳添加量:3%葡萄糖,2.0%蛋白胨,1.5%酵母膏,生物量、色素含量和产量分别为11.38g/L、120.63μg/g、1.37mg/L,最佳培养条件为pH值为6.0,温度30℃,转速160r/min,培养时间168h,此条件下的生物量、色素含量和产量分别为14.38g/L、176.6μg/g、2.54mg/L,其中产量提高了85.4%。最后优化了蔗糖组各组分的最佳添加量:4%蔗糖,1.5%磷酸氢二铵,1%酵母膏,产量为2.53mg/L。     

碱预处理秸秆同步糖化发酵生产丁二酸

研究了碱预处理秸秆及用琥珀酸放线杆菌Actinobacillus sucinogenes同步糖化发酵秸秆生产丁二酸。结果表明:用1.0%NaOH溶液于120℃分别预处理玉米、小麦和水稻3种秸秆2 h,其木质素的脱除率、纤维素与半纤维素的总保留率均在85%以上。以3种碱预处理后的秸秆为原料,在补加纤维素酶与纤维二糖酶的条件下,A.sucinogenes F3-21摇瓶厌氧发酵72 h,产丁二酸浓度分别为30.74 g/L、24.98 g/L和26.57 g/L;在7 L罐中厌氧发酵72 h,丁二酸浓度分别达到40.21 g/L,30.06 g/L和39.07 g/L,每克预处理秸秆产丁二酸分别为0.50g、0.38 g和0.49 g。并用钙盐法对玉米秸秆同步糖化发酵液进行提取,得到纯度为99.98%的丁二酸结晶。说明了玉米、小麦和水稻3种秸杆为原料进行同步糖化发酵生产丁二酸的可行性。     

响应面法优化酿酒酵母产孢培养基及单倍体的鉴定

采用响应面法对酿酒酵母4608菌种的产孢培养基进行了优化。用Plackett-Burman方法对影响培养各因素的效应进行评价,筛选出有显著效应的3个因素：酵母膏、蛋白胨和葡萄糖;通过中心组合实验及响应面分析优化此3个主要因素。采用优化后的条件,酵母膏2.8 g/L,蛋白胨1.2 g/L,葡萄糖0.48 g/L,经培养验证,实测值与预测值间有-0.58%的偏差,实际酵母产孢率为44.12%,比优化前的产孢率提高了60.4%。利用PCR技术检验酵母的单倍体,验证了酵母的交配型,方法准确、迅速。     

产高光学纯度L-乳酸菌株HY-38发酵培养基优化

以产L-乳酸光学纯度为99.3%的粪肠球菌（Enterococcus faecium）HY-38作为出发菌株,通过Plackett-Burman试验设计确定影响L-乳酸的产量的主要因素,筛选出3个有显著影响效应的因素,分别为葡萄糖、酵母膏及乙酸钠,最陡爬坡试验逼近影响因素最佳值区域,采用Box-Behnken设计及响应面分析对L-乳酸发酵培养基成分进行优化。结果表明,L-乳酸发酵培养基成分确定为葡萄糖148 g/L、酵母膏12.4 g/L、碳酸钙80 g/L、乙酸钠5.0 g/L、磷酸二氢钾1.0 g/L、硫酸镁1.2 g/L、硫酸锰0.04 g/L,在此条件下,L-乳酸的产量达到134.7g/L,比优化前（108.3 g/L）提高了24.3%。     

玉米皮渣类纤维兼氧发酵产丁二酸

采用酶酸两步法水解玉米皮渣,重点考察了稀HCl水解条件变化对还原糖产率的影响,并以产琥珀酸放线杆菌为发酵菌株,探讨以玉米皮渣类纤维为原料替代葡萄糖为碳源,兼氧发酵产丁二酸的可行性。结果表明:在HCl浓度1.5%,底物浓度为12%,100℃水解4h的水解工艺下,还原糖产率达83%。在还原糖质量浓度40g/L,玉米浆为氮源,35℃发酵60h的条件下,丁二酸产率达到19.41g/L。应用玉米加工副产物玉米皮渣和玉米浆为原料发酵产丁二酸具有良好的应用前景。     

近平滑假丝酵母发酵产甘露醇

从甘蔗汁中筛选出1株利用葡萄糖产甘露醇的菌株,经鉴定为近平滑假丝酵母(Candida parapsilosis)。研究其发酵生产甘露醇的条件,通过单因素实验和正交实验优化后,培养基配方为:200 g/L葡萄糖,30 g/L酵母膏,0.05 g/L CaCl2·2H2O,0.02 g/L FeCl3·2H2O,0.5 g/L MgSO4·7H2O,此条件下摇瓶培养甘露醇产量为61.7 g/L。进行30 L发酵罐扩大培养,根据发酵曲线得知72 h时甘露醇最大产量为80.3 g/L。     

黑曲霉SFGT601产葡萄糖酸钠发酵培养基及工艺条件的研究

以一株耐高温、耐高糖的葡萄糖酸钠生产菌株Aspergillus niger SFGT601为研究对象,在前期研究工作的基础上,首先利用5 L发酵罐对其发酵培养基组成进行了优化,得到了理想的培养基组成为葡萄糖320 g/L,玉米浆3.5 g/L,酵母膏2.0 g/L,硫酸镁1.5 g/L,然后进一步考察了pH值和溶解氧对其发酵的影响,确定了最佳的pH和溶解氧控制策略为溶解氧20%,0～8 h控制pH值5.5～6.0,8～22 h控制pH值5.0～5.5。在此最佳工艺条件下菌株SFGT601的葡萄糖酸钠产量提高到326.0 g/L。     

菠萝皮渣生产虾青素的发酵条件研究

以菠萝皮渣为培养基的主要原料,采用法夫酵母（Phaffia rhodozyma）对其进行发酵生产虾青素,采用响应面分析法对法夫酵母的发酵条件进行优化研究。先用Plackett-Burman设计法实验确定重要因素,再用最陡爬坡实验法确定因素水平,最后用响应面分析方法求得的最佳发酵条件为：发酵温度为20.0℃,初始pH为5.29,糖度为6.1%,酵母膏2g/L,MgSO42g/L,（NH4）2SO44g/L,KH2PO41.5g/L,种龄36h。用此优化的发酵培养基培养法夫酵母,虾青素产量可达6.5751mg/L。     

响应面试验优化产琥珀酸放线杆菌GXAS137发酵粗甘油产丁二酸工艺

通过优化产琥珀酸放线杆菌GXAS137发酵粗甘油产丁二酸的培养基,提高丁二酸产量,降低生产成本。先通过单因素试验对粗甘油发酵产丁二酸的电子受体、初始粗甘油质量浓度及氮源进行了优化,再利用响应面试验确定重要参数的最佳水平。结果表明：二甲基亚砜（dimethyl sulfoxide,DMSO）为最适电子受体,玉米浆可替换酵母粉作为氮源,各因素的最佳条件为：初始粗甘油质量浓度55.43?g/L、DMSO质量浓度10.35?g/L、玉米浆质量浓度17.69?g/L。优化后丁二酸产量达到37.02?g/L,丁二酸得率为66.79%,生产强度为0.51?g/（L·h）。与初始条件下丁二酸产量（16.88?g/L）相比,优化后提高了1.19?倍。本研究为微生物发酵粗甘油原料生产丁二酸提供了理论支持。     

Optimization of Lactic Acid Production by Lactobacillus delbrueckii through Response Surface Methodology

ABSTRACT: This article describes the optimization through response surface methodology of a low-cost medium based on Corn Steep Liquor (CSL) for lactic acid production by Lactobacillu delbrueckii NRRL B445. The effect of the fermentation time was also considered. A maximum lactic acid concentration (93.4 g/L) was predicted using 15 g of CSL/L and 6 g of yeast extract/L at a fermentation time of 80.1 h. However, the maximum productivity (3.50 g/L/h) was predicted by using 15 g of CSL/L, 6 g of yeast extract/L, and 8.9 g of peptone/L after 24 h. From an economical perspective, better results were obtained using 15 g of CSL/L, 6 g of yeast extract/L, and 8.9 g of peptone/L after 24 h. From an economical perspective, better results were obtained using 15 g of CSL/L alone and 24 h, achieving a maximum economical productivity of 229.7 g of lactic acid per hour and considerable savings in nutrients.     

Production of malic and succinic acids by sugar-tolerant yeast <Emphasis Type="Italic">Zygosaccharomyces rouxii</Emphasis>

Zygosaccharomyces rouxii V19 was grown in YPG medium (yeast extract, 0.5%, peptone, 1.0%, glucose, 10%). Fermented broth was purified through a series of ion-exchange columns and ODS column and the purified sample was TMS-esterified. Malic and succinic acids were identified with GC-MS analysis. The yeast was cultivated under various cultural conditions and quantitative determination of the organic acids was carried out with HPLC on Shodex column. Glucose concentration of 30%, initial pH 5.0, and 25 °C incubation temperature were the optimum conditions. Inclusion of glutamic, malic, and succinic acid precursors in the medium increased the production of malic acid. On the other hand, only addition of malic acid enhanced the production of succinic acid. Maximum amount of malic acid produced was 74.9 g/L (32.8% yield, based on glucose consumption) in the medium with 0.5% glutamic acid supplement, and that of succinic acid was 7.7 g/L (8.1% yield) when 0.3% malic acid was added in the medium.     

一种新的检测啤酒有害菌培养基的优化

为研制出更适合国产啤酒有害菌检测的培养基,参考目前国内啤酒行业使用量最大的2种进口培养基MRS和NBB,利用2水平正交试验考察牛肉浸粉、酵母浸出物、葡萄糖、吐温-80、麦根浸出物、精氨酸、叶酸等因素对菌落数的影响。主要的影响因素是:牛肉浸粉、酵母浸出物、葡萄糖和叶酸,最优的培养基配方为:牛肉浸粉8 g/L、酵母浸出物6 g/L、葡萄糖18 g/L、叶酸0.22 g/L。并且通过反复实验,确定此配方为最佳的培养基配方。     

L-鸟氨酸发酵用培养基的改进研究

利用价格低廉的废酵母制作酵母水解液替代酵母浸膏做有机氮源,加入丁二酸做调控物对产L-鸟氨酸的谷氨酸棒杆菌进行发酵培养。结果表明,使用废酵母作为有机氮源后,L-鸟氨酸的产量增加了26.4%。加入1.0%的丁二酸,L-鸟氨酸的产量提高了10.4%。     

Characterization of composition,antioxidant potential and microbial organisms upon submerged <Emphasis Type="Italic">Cicer arietinum</Emphasis> fermentation

The aim of this work was to investigate the composition, antioxidant potential and microbial content of chickpea (Cicer arietinum) steep liquor (CSL) during a submerged fermentation. Chickpea seeds (250 g) were soaked in boiled distilled water (1:2, w/v) for 24 h at 37 °C then filtered and freeze-dried to obtain 8.2 g of CSL. Lysine was the main amino acid accounted for 77.0 % of total free amino acids followed by serine (6.49 %). The results of total amino acids found in CSL indicated that arginine was the main amino acid accounted for 24.0 % of total amino acids followed by tyrosine (20.0 %). Total carbohydrate in the freeze-dried CSL was 1.47 %, wherein reducing sugar was 1.25 % of total carbohydrates. Levels of nicotinic acid, pyridoxine, thiamin, riboflavin, folic acid, and vitamin B₁₂ were 14.3, 3.14, 24.2, 1.11, 0.59 and 24.5 mg/100 mg CSL, respectively. CSL exhibited antioxidant activity (AA) wherein AA was increased with increasing the fermentation time. After 24 h of fermentation, AA of CSL reached 77.0 % while tertiary butyl hydroquinone exhibited 82.0 %. Twenty-five Bacilli isolates were separated from freeze-dried CSL on nutrient broth medium. CSL might be used as an alternative to yeast extract for syngas fermentation because it is rich in nutrients and cheaper compared to yeast extract.     

Optimization of succinic acid production from cane molasses by Actinobacillus succinogenes GXAS137 using response surface methodology (RSM)

A method combining a Plackett-Burman design (PBD), the steepest ascent method (SA), and a Box-Behnken design (BBD) was developed to optimize succinic acid production from cane molasses by Actinobacillus succinogenes GXAS137. The important parameters were (g/L): total sugars of cane molasses (85 g/L), yeast extract (8.84 g/L), and MgCO₃ (63.1 g/L). Verification experiments indicated that the maximal succinic acid production reached 57.43±0.86 g/L, which agreed with the predicted value (57.12 g/L). In addition, batch and fed-batch fermentations were carried out in a 1.3 L stirred bioreactor. Compared with a batch fermentation that produced 57.96 g/L of succinic acid at 60 h, a fed-batch fermentation, performed to minimize the inhibition effect of the substrate, produced 64.34 g/L of succinic acid at 60 h. The combined method is powerful for selection of optimized conditions for succinic acid production from cane molasses.     

响应面法优化枯草芽孢杆菌3-羟基丁酮发酵培养基

采用响应面法对枯草芽孢杆菌TH-55 3-羟基丁酮发酵培养基进行了优化,确定了葡萄糖、酵母浸膏和玉米浆是影响菌株3-羟基丁酮发酵产率的主要因素.优化获得的发酵培养基组成:葡萄糖102g/L,酵母浸提物6.8g/L,玉米浆26.5g/L,硫酸铵5g/L,硫酸锰0.05g/L,硫酸镁0.6g/L,磷酸二氢钾0.5g/L.在此条件下,菌株摇瓶发酵3-羟基丁酮平均产率达到46.25g/L,较优化前的菌株产率35.21g/L相比提高了31％.10L发酵罐发酵试验,发酵周期72h,3-羟基丁酮发酵产率达到47.85g/L.