酿酒酵母发酵生产谷胱甘肽的研究

以诱变获得的酿酒酵母突变株YF(ZnCl2r,Ethr)为试验菌株,通过摇瓶发酵、发酵罐补料分批发酵,对突变株发酵生产谷胱甘肽进行研究.确定发酵罐分批发酵的最佳培养条件为:温度30℃,pH 6.0,接种量为20%,搅拌转速为150 r/min,通气量为250 L/h.在补料分批操作方式下,分别考察了摇瓶培养、发酵罐培养...     

酿酒酵母生产谷胱甘肽的营养条件研究

通过L9(34)正交实验考查了培养基中的葡萄糖浓度、尿素浓度和磷酸二氢钾浓度对酿酒酵母KH37合成谷胱甘肽的影响。结果表明,葡萄糖浓度为影响谷胱甘肽产量的主要因素,其次是尿素浓度和磷酸二氢钾浓度。最优培养基组成为:35g/L葡萄糖、100mg/L尿素和250mg/L磷酸二氢钾。方差分析表明,葡萄糖浓度对谷胱甘肽产量的影响作用显著,而其他2个因素(尿素和磷酸二氢钾)对谷胱甘肽产量无显著影响。     

产胞外谷胱甘肽酿酒酵母的诱变选育及发酵优化

为获得一株能产胞外谷胱甘肽（glutathione,GSH）的突变株,对酿酒酵母GAQ4进行紫外迭代诱变处理,最终筛选得到突变菌株UV3-10,其胞外谷胱甘肽含量为18.56 mg/L,是出发菌株GAQ4胞外谷胱甘肽含量的2.52倍。为进一步提高胞外谷胱甘肽含量,通过单因素试验优化突变株UV3-10发酵条件,得到其最优摇瓶发酵条件为发酵周期48 h、发酵温度34℃、摇瓶转速140 r/min、摇瓶装液量75 mL/300 mL、初始pH值为6.5;优化后其胞外GSH含量达到52.05 mg/L,是发酵条件优化前胞外GSH含量的2.80倍。     

酿酒酵母生产谷胱甘肽的培养条件的研究

本实验对酿酒酵母(Saccharomyces cerevisiae)CS10515产谷胱甘肽的培养条件进行了初步研究,确定了其最佳培养基组成为:葡萄糖为5%、酵母膏1.2%、硫酸铵0.6%、硫酸镁0.02%、磷酸二氢钾0.1%;当发酵液初始pH为6.0、装液量50%～60%、振荡速度300r/min时,经过24h振荡培养后,谷胱甘肽的产量为90.20mg/L。     

谷胱甘肽生产菌株的选育及培养条件研究

以Saccharomyces cerevisiae WZ-36为出发菌株,通过紫外诱变结合ZnCl2平板筛选、硫酸二乙酯结合乙硫氨酸联合处理,获得一株高产GSH的酿酒酵母优良菌株Saccharomyces cerevisiaeSE-4。该菌株具有稳定的遗传性能。经过培养条件的优化,其GSH产量达到85.45 mg/L,比出发菌株提高73.1%。     

酿酒酵母生产谷胱甘肽分批发酵动力学研究

以麦芽汁为发酵培养基,对7.5L 自动发酵罐中酿酒酵母Y518 分批发酵生产谷胱甘肽的实验数据进行分析,建立谷胱甘肽分批发酵动力学模型。通过对符合菌体生长的Logistic 方程、产物生成的Luedeking-Piret 方程和基质消耗的物料衡算方程进行最优参数估计和非线性拟合,分别得到了相应的动力学模型和最佳模型参数值。对动力学模型的拟合曲线进行分析,发现模型的计算值与实验值能较好地拟合,表明本实验建立的分批发酵动力学模型能较好地反映谷胱甘肽分批发酵过程。     

高产谷胱甘肽酵母菌株的选育

以BY-14面包酵母（Saccharomyces cerevisiae）为出发菌株,通过紫外线和氮离子注入复合诱变,氯化锌、乙硫氨酸耐性平板筛选,获得一株高产谷胱甘肽的面包酵母优良菌株（S．cerevisiae）BL-23。该菌株经摇瓶发酵谷胱甘肽产量为113．46mg／L,较出发菌株提高62％,每1g干细胞含谷胱甘肽20．86mg,较出发菌株提高56％。传代培养结果表明,该菌株具有稳定的遗传性能。     

不同发酵时期添加金属离子对酿酒酵母合成谷胱甘肽的影响

通过摇瓶发酵培养,研究了Cu2+,Mg2+,K+,Fe2+,Mn2+5种金属离子在不同发酵时间添加对酿酒酵母CS10515-1生产谷胱甘肽的影响。实验结果表明:在发酵初期(0 h),当K+、Mg2+、Fe2+添加量分别为0.15、0.12、0.09 g/L时,GSH的产量分别为88.53、52.73、41.42 mg/L,相比空白对照分别提高了63.50%、36.58%和44.25%。在15 h时,当Mg2+添加量为0.09 g/L时,GSH产量为61.75 mg/L,比对照组提高82.01%。当发酵至24 h时,金属离子的添加对GSH的产量无明显促进作用。     

一株德国酿酒酵母无抗性电转化条件的研究

无抗性基因转化是实现转基因食品安全性的重要途径之一,转化子筛选是该技术面对的最大瓶颈.本研究以一株德国酿酒酵母NSLA112为材料,探讨了电激转化过程中各参数对该细胞存活率的影响.结果表明:①该酵母与国内常见酿酒酵母有较大差别,电激转化参数需要随不同酵母种类进行调整;②无筛选标记的转化方法要求细胞具有较高的转化效率,同时降低转化操作后细胞的存活数量,以提高筛选工作的效率,较好地平衡了细胞死亡率与转化效率的关系.     

响应面法优化酿酒酵母谷胱甘肽的提取条件

利用Box-Benhnken 中心组合设计和响应面法优化乙醇提取酿酒酵母胞内谷胱甘肽的条件。结果表明,谷胱甘肽最佳提取条件为乙醇体积分数43.7%、乙醇添加量7.03mL/0.1g 干酵母粉、抽提时间80min、谷胱甘肽提取率达最大为9.54mg/g。     

The adaptive response of Saccharomyces cerevisiae to mercury exposure

The budding yeast Saccharomyces cerevisiae has been shown to possess a number of discrete but overlapping adaptive stress responses. We show here that yeast has an adaptive stress response towards mercury and that this response overlaps to some extent with the H(2)O(2) and cadmium-inducible stress responses. Expression of the yeast GSH1 gene, encoding gamma-glutamylcysteine synthetase, is known to be regulated by hydrogen peroxide; in this study we show that expression of a GSH1-lacZ reporter gene is shown to be regulated by exposure to heavy metals, such as mercury and cadmium. Other redox-active metals, including copper and iron, were found not to induce GSH1 expression. We show that mercury-mediated regulation of the GSH1 gene is not by the same mechanism used by cadmium. Moreover, our experiments suggest the possibility that the oxidative stress produced by mercury exposure is similar to that produced by treatment with H(2)O(2), consistent with our finding that the Yap1 protein is also involved in the response of yeast towards mercury.     

酿酒酵母工业菌株胁迫条件耐受性分析

对酿酒酵母（Saccharomyces cerevisiae）工业菌株胁迫条件，包括高浓度酒精、高渗透压、高温、营养饥饿、氧化胁迫、糠醛毒性的耐受性进行了分析，同时测定了抗生素G418对这些菌株的最低抑菌浓度。结果表明，所测定的酵母菌株对这些逆境条件的耐受性有明显差别，表现出良好耐受性的是6508和安琪酵母菌株，同时多倍性的酿酒酵母工业菌株的耐受性均比单倍性实验室菌株高。     

外源性氧化胁迫对酿酒酵母突变株Y518合成谷胱甘肽的影响

利用外源过氧化氢对酿酒酵母突变株Y518进行氧化胁迫来研究外源性氧化胁迫对Y518合成谷胱甘肽的影响。结果表明:添加过氧化氢会抑制Y518细胞生长,但会促进其合成谷胱甘肽;当过氧化氢的添加时间为24h,添加量为0.6mmol/L时,Y518胞内谷胱甘肽含量达到(13.69±0.28)mg/g,比未添加过氧化氢时提高了约14%;在24h时添加0.6 mmol/L过氧化氢会对Y518产生外源性氧化胁迫,激活转录调节子YAP1和SKN7调控γ-谷氨酰半胱氨酸合成酶和谷胱甘肽合成酶编码基因GSH I和GSH II的表达,提高γ-谷氨酰半胱氨酸合成酶和谷胱甘肽合成酶的活力,以促进Y518合成谷胱甘肽。因此,添加外源过氧化氢能够使酿酒酵母突变株Y518产生外源性氧化胁迫,促进Y518进一步合成谷胱甘肽。     

基于酶活性调节的酿酒酵母谷胱甘肽发酵调控研究

研究了酿酒酵母分批补料发酵合成谷胱甘肽（GSH）过程中pH与温度对GSH产量的影响。通过先研究工程菌所表达的酿酒酵母中γ-谷氨酰半胱氨酸合成酶在不同pH及温度下的酶学特性,再以此为基础在分批补料发酵过程进行pH值和温度控制的优化。结果表明：与初始发酵条件相比,pH控制在5.5~7.5的变化范围内菌体生物量达到（44.80±1.20）g/L,胞内GSH含量为（19.74±0.51）mg/g,GSH产量为（884.35±27.30）mg/L,分别提高了10.07%、3.35%、13.76%。当温度控制在35℃时,菌体生物量达到（46.30±1.55）g/L,胞内GSH含量为（19.84±0.44）mg/g,GSH产量为（918.59±29.22）mg/L,分别提高了3.87%、13.70%、18.17%。研究表明在发酵过程中,通过对pH控制和温度的优化来提高GSH产量是有效的。     

The positive relationship between codon usage bias and translation initiation AUG context in Saccharomyces cerevisiae

The relationship between the codon usage bias and the sequence context surrounding the AUG translation initiation codon was examined in 211 Saccharomyces cerevisiae mRNA sequences. The codon usage bias and the number of matches to optimal AUG context, (A/U)A(A/C)AA(A/C)AUG UC(U/C), for translation initiation showed a positive relationship, indicating that these two factors are evolutionally under the similar natural selection constraint at the translation level. A new index (A_UGCAI=AUG Context Adaptation Index) for the measure of optimal AUG context was devised, and the importance of each position of AUG context was also examined. Copyright © 1999 John Wiley & Sons, Ltd.     

酿酒酵母温度敏感性突变株的选育

为获得酵母胞内产物的高效分泌,以酿酒酵母二倍体(2n)及单倍体(n)为出发菌,经紫外诱变处理,筛选获得5株可能具有温度敏感性的突变株。为进一步鉴定,以野生菌Y_1为对照菌,测定其胞外核酸、蛋白质及果糖-1,6-二磷酸(FDP)的含量,发现突变菌株Ts_4(2n)自溶程度最高,其核酸、蛋白质渗透率达1.709,1.483,胞外FDP浓度为38μg/mL,较Y_1(2n)提高了24.1%。此外突变株Ts~*_2(n)、Ts~*_3(n)也会发生一定程度的自溶。因此,该试验共获得温度敏感性突变株3株,即Ts_4(2n)、Ts~*_2(n)和Ts~*_3(n)。     

A new strategy for improved glutathione production from Saccharomyces cerevisiae: use of cysteine‐ and glycine‐rich chicken feather protein hydrolysate as a new cheap substrate

BACKGROUND: Glutathione (GSH) is composed of the amino acids glutamic acid, cysteine and glycine. This study investigated the usability of chicken feather protein hydrolysate (chicken feather peptone, CFP) as a substrate for GSH production from Saccharomyces cerevisiae. RESULTS: CFP was found to be rich in ash (36.7 g per 100 g), protein (61.1 g per 100 g) and minerals (S, P, K, Ca, Fe, Na and Mg). It also had high contents of cysteine and glycine. CFP augmented biomass and GSH production by 53 and 115% respectively compared with the control medium. The highest biomass (17.4 g l^?1) and GSH (271 mg L^?1) concentrations were attained in CFP medium. The second highest biomass (16.8 g l^?1) and GSH (255 mg L^?1) concentrations were obtained in fish peptone medium. It was assumed that the high mineral, cysteine and glycine contents of CFP were related to cell growth and GSH synthesis in S. cerevisiae. CONCLUSION: This is the first report on the effect of cysteine‐ and glycine‐rich protein hydrolysates on GSH production from S. cerevisiae. In this regard, CFP was tested for the first time as a GSH production substrate. As an additional contribution, a new hydrolysis process was developed for the preparation of protein hydrolysates. © 2012 Society of Chemical Industry