啤酒酵母对Zn~(2+)、Mn~(2+)和Cu~(2+)的吸附探究

文中利用啤酒酵母去除模拟废水中Zn2+、Mn2、Cu2+,通过对预处理试剂、吸附温度、吸附液pH值与浸泡时间等因素进行正交分析,确定了影响吸附的主要因素是酸度和预处理试剂.研究pH值、离子初始浓度、吸附时间、离子强度等条件对吸附率的影响,结果表明,用NaOH浸泡后2h,在pH=5~6时吸附效果最好.用吸附等温线Langmuir(exe)、Freundlich和Temkin方程拟合,相关性都比较好.用不同的吸附动力学方程描述啤酒酵母吸附金属离子的最优模型为Elovich方程.     

Effects of proteinase a on cultivation and viability characteristics of industrial Saccharomyces cerevisiae WZ65

Proteinase A (PrA), encoded by PEP4 gene, is a key enzyme in the vacuoles of Saccharomyces cerevisiae. We characterized the effects of PrA on cell growth and glucose metabolism in the industrial S. cerevisiae WZ65. It was observed that the lag phase of cell growth of partial PEP4 gene deletion mutant (36 h) and PrA-negative mutant (48 h) was significantly ex-tended, compared with the wild type strain (24 h) (P<0.05), but PrA had no effect on glucose metabolism either under shaking or steady state cultivations. The logistic model was chosen to evaluate the effect of PrA on S. cerevisiae cell growth, and PrA was found to promote cell growth against insufficient oxygen condition in steady state cultivation, but had no effect in shaking culti-vation. The effects of glucose starvation on cell growth of partial PEP4 gene deletion strain and PrA-negative mutant were also evaluated. The results show that PrA partial deficiency increased the adaption ofS. cerevisiae to unfavorable nutrient environment, but had no effect on glucose metabolism under the stress of low glucose. During heat shock test, at 60 ℃ the reduced cell viability rate (RCVR) was 10% for the wild type S. cerevisiae and 90% for both mutant strains (P<0.01), suggesting that PrA was a negative factor for S. cerevisiae cells to survive under heat shock. As temperatures rose from 60 ℃ to 70 ℃, the wild type S. cerevisiae had significantly lower relative glucose consumption rate (RGCR) (61.0% and 80.0%) than the partial mutant (78.0% and 98.5%) and the complete mutant (80.0% and 98.0%) (P<0.05), suggesting that, in coping with heat shock, cells of the PrA mutants increased their glucose consumption to survive. The present study may provide meaningful information for brewing industry; however, the role of PrA in industrial S. cerevisiae physiology is complex and needs to be further investigated.     

Construction of recombinant industrial Saccharomyces cerevisiae strain with bglS gene insertion into PEP4 locus by homologous recombination

The bglS gene encoding endo-1,3-1,4-β-glucanase from Bacillus subtilis was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeast mating pheromone α-factor (MFals), and ADH1 terminator with G418-resistance as the selected marker, was constructed. Then one of the PEP4 allele of Saccharomyces cerevisiae WZ65 strain was replaced by bglS expression cassette using chromosomal integration of polymerase chain reaction (PCR)-mediated homologous recombination, and the bglS gene was expressed simultaneously. The recombinant strain S. cerevisiae (SC-βG) was preliminarily screened by the clearing hydrolysis zone formed after the barley β-glucan was hydrolyzed in the plate and no proteinase A (PrA) activity was measured in fermenting liquor. The results of PCR analysis ofgenome DNA showed that one of the PEP4 allele had been replaced and bglS gene had been inserted into the locus of PEP4 gene in recombinant strains. Different endo-1,3-1,4-β-glucanase assay methods showed that the recombinant strain SC-βG had high endo-1,3-1,4-β-glucanase expression level with the maximum of 69.3 U/(h-ml) after 60 h of incubation. Meanwhile, the Congo Red method was suitable for the determination of endo-1,3-1,4-β-glucanase activity during the actual brewing process. The current research implies that the constructed yeast strain could be utilized to improve the industrial brewing property of beer.     

高产乙醇酿酒酵母的筛选鉴定及发酵条件优化

从酵母浸粉中分离筛选出一株高产乙醇的菌株DL5168,经形态学观察、生理生化学及分子生物学鉴定,确定该菌株为酵母属的酿酒酵母(Saccharomyces cerevisiae)。通过优化实验,确定菌株DL5168发酵的最适条件为:初始葡萄糖浓度180 g/L;发酵温度30℃。在此条件下,菌株发酵的最终乙醇浓度为113.9 g/L,比对照菌株的乙醇浓度提高36%;乙醇转化率为0.64 g/g,比对照提高39%。     

啤酒酵母阻断白色念珠菌感染的实验研究

目的:探讨啤酒酵母菌对白色念珠菌感染的影响作用及机制.方法:用啤酒酵母免疫家兔后,经家兔耳的皮下注射白色念珠菌,建立播散性念珠菌病动物感染模型,观察啤酒酵母菌免疫组和对照组家兔的感染状况;通过测定抗体效价和巨噬细胞吞噬功能,了解啤酒酵母的免疫效果.结果:观察显示:①免疫组兔耳皮下注射区红肿面积明显小于对照组;②肾脏充血及肿胀程度免疫组小于对照组,同时,对照组肾脏出现肉眼可见的脓肿灶;③病理诊断显示,免疫组炎性细胞浸润范围小;④免疫组抗体效价明显高于对照组,吞噬百分率与吞噬指数,免疫组与对照组有明显差异(P<0.01).结论:啤酒酵母能够提高机体免疫功能,减轻白色念珠菌的局部感染及全身感染.     

紫外诱变酿酒酵母筛选耐高温菌株

以实验室保存的酿酒酵母为初始菌株,采用紫外分光光度法测定菌株浓度,绘制出菌株生长曲线,由此确定出最佳诱变菌龄为3～10h,在此期间利用紫外线对菌株进行诱变,筛选出一株适于在高温下发酵的菌株,紫外线诱变条件为：紫外灯功率10w,照射距离30cm,照射时间3min。此菌株在37℃下培养72h,其成熟发酵醪酒精产率为3．837％。     

水稻微卫星标记的研究进展

微卫星又称简单重复序列,是一类由几个核苷酸(一般1～6个)为重复单元而形成的串联重复序列.由于它具有含量丰富、多态性高、共显性和检测方法简单等优点,而广泛应用于品种鉴定、种质资源保护、遗传作图、基因定位和QTL分析等方面.文章就微卫星标记在水稻中的开发和应用进展作一概述.     

大气压冷等离子体提高乙醇转化率的实验参数优化研究

以酿酒酵母(Saccharomyces cerevisiae)为研究对象,研究大气压冷等离子体激活酿酒酵母提高乙醇转化率的工艺条件。在单因素实验基础上,选取等离子体处理时间、等离子体电源电压和处理菌液体积为影响因子,以乙醇转化率为响应值,应用Box-Behnken中心组合实验建立数学模型,进行响应面分析。结果表明,大气压冷等离子体提高乙醇转化率的最佳实验参数为:处理时间1 min,电源电压24 V,处理菌液体积9 mL。在此条件下,乙醇转化率达到0.58 g/g,比未处理过的酿酒酵母发酵葡萄糖生成乙醇的转化率高23.6%。     

Rumen fermentation and acetogen population changes in response to an exogenous acetogen TWA4 strain and Saccharomyces cerevisiae fermentation product

The presence of yeast cells could stimulate hydrogen utilization of acetogens and enhance acetogenesis. To understand the roles of acetogens in rumen fermentation, an in vitro rumen fermentation experiment was conducted with addition of acetogen strain (TWA4) and/or Saccharomyces cerevisiae fermentation product (XP). A 2×2 factorial design with two levels of TWA4 (0 or 2×10⁷ cells/ml) and XP (0 or 2 g/L) was performed. Volatile fatty acids (VFAs) were increased (P<0.05) in XP and TWA4XP, while methane was increased only in TWA4XP (P<0.05). The increase rate of microorganisms with formyltetrahydrofolate synthetase, especially acetogens, was higher than that of methanogens under all treatments. Lachnospiraceae was predominant in all acetogen communities, but without close acetyl-CoA synthase (ACS) amino acid sequences from cultured isolates. Low-Acetitomaculum ruminis-like ACS was predominant in all acetogen communities, while four unique phylotypes in XP treatment were all amino acid identified low-Eubacterium limosum-like acetogens. It differs to XP treatment that more low-A. ruminis-like and less low-E. limosum-like sequences were identified in TWA4 and TWA4XP treatments. Enhancing acetogenesis by supplementation with an acetogen strain and/or yeast cells may be an approach to mitigate methane, by targeting proper acetogens such as uncultured low-E. limosum-like acetogens.     

基于支持向量机的酵母重组热点和冷点的预测

使用基于统计学习理论的支持向量机(SVM)方法,提出了针对重组热点和冷点分类预测的新方法.对酵母基因组的303个重组热点开放阅读框(hot ORF)以及48个重组冷点开放阅读框(cold ORF),提取了序列的一般二联碱基丰度特征,以及基于密码子使用偏性的二联碱基丰度特征,然后使用二倍交叉验证方法,选择不同的核函数和对应参数,对数据集进行了训练和分类预测.研究结果表明,当使用径向基核函数,并采用基于密码子使用偏性的二联碱基丰度特征时,预测准确率为87·47%.     

固定化醋酸菌酿造火棘果醋的工艺研究

以火棘为原料,对采用固定化醋酸菌酿造火棘果醋的醋酸发酵工艺进行了研究。对发酵温度、接种量、酒精度三个影响因素进行正交试验,结果表明,固定化醋酸菌酿造火棘果醋的最佳工艺为:发酵温度34℃,接种量10%,酒精度7%。所得火棘果醋醋香浓郁,酸甜适度,香气自然、协调,是一种值得开发的保健果醋。     

硫酸铁催化合成乙酸乙酯

在硫酸铁存在下，乙醇与冰醋酸发生酯化合成了高收率的乙酸乙酯．研究了硫酸铁、乙醇和冰醋酸用量对酯化反应收率的影响．乙酸、乙醇和硫酸铁的恰当摩尔比为1：2．5：0．025，回流反应1h，产品收率达42．6%。     

电导法测定弱电解质醋酸的电离平衡常数

采用DDS— 12A型电导率仪和HS— 4精密恒温浴槽 ,用电导法测定了 2 5℃条件下弱电解质醋酸的电离平衡常数Kc为 1.6 6× 10 -5,与理论值 1.75× 10 -5相比 ,略为偏小 ,可能是系统误差造成的     

Recovery of Dilute Acetic Acid by Catalytic Distillation Using NKC-9 as Catalyst

The reaction kinetics of dilute acetic acid with methanol using NKC-9 as catalyst was studied at temperatures of 308 K, 318 K, 323 K, 328 K. The kinetic model based on Langmuir-Hinshel-wood rate model was derived and the activation energy was 6.13×104 kJ/kmol. The experiment of recovery of dilute acetic acid was conducted in a packed bed catalytic distillation column. The optimal process parameters and operational conditions determined to make up to 85.9% conversion of acetic acid are as follows:the height of catalyst bed is 1 100 mm, reflux ratio is 4:1, and the ratio of methanol to acetic acid is 2:1. The method can be used as a guide in industrial scale recovery of 15%-30% dilute acetic acid.     

Identification of candidate genes for drought stress tolerance in rice by the integration of a genetic （QTL） map with the rice genome physical map

INTRODUCTION Drought stress is a major constraint to rice(Oryza sativa) production and yield stability in rainedecosystems (Dey and Upadhyaya, 1996). Rice mustbe made more drought tolerant, but this is a somewhatcontradictory objective considering that rice is mostcommonly grown under flooded conditions. Achiev-ing drought tolerance in rice will require a deeperunderstanding of the possible physiological mecha-nisms available for water stress tolerance and theidentification of favo…     

混合氯化稀土催化合成乙酸正丁酯

研究了以混合氯化稀土为催化剂,乙酸和正丁醇为原料合成乙酸正丁酯,并考察了影响反应的因素。结果表明：正丁醇与乙酸物质的量之比为2．5：1,催化剂用量为0．25g,带水剂为环己烷,用量为2ml,反应时间1．5h时,反应效果最佳,其酯化率可达95．98％。     

植酸酶产生菌的筛选及产酶动态初探

用平皿培养法根据植酸钙溶解圈的有无从34种已知菌种中得到28株菌在0．1％植酸钙平板分离培养基上有明显的透明圈（占已知菌的82．4％），从中选黑曲霉，白地霉，毕赤酵母，酿酒酵母四株在0．1％植酸钙为唯一磷源的合成培养基中进行产酶动态分析，通过实验得到如下结论：[1]、许多微生物都能产生植酸酶．[2]、在0.1％植酸钙为磷源的合成培养基中，白地霉、黑曲霉均在培养6天酶活最高；酿酒酵母、毕赤酵母培养3天酶活最高；黑曲霉产酶最高，可达9．6IU／ml；毕赤酵母7．21U／ml；酿酒酵母6．0IU／ml；白地霉最低，酶活仅5．0IU／ml．     

Identification of Rhodiola species by using RP-HPLC

INTRODUCTION The roots of Rhodiola species, one of the im-portant traditional Chinese herbal medicines, have anti-viral (Sun et al., 1993), anti-tumor (Wang et al., 1992), anti-ageing (Yi et al., 1992), anti-oxygen de-ficiency, anti-radiation (Luo et al., 1996) effects and other pharmacological properties (Xu et al., 2000). Ten Rhodiola species distribute in the Tianshan Mountains areas of China. Biologically active com-pounds content in the roots has large variation and the value of…     

参红补血颗粒薄层色谱鉴别研究

采用薄层层析法对参红补血颗粒中的红景天、红参、黄精、白术进行定性鉴别.结果表明,红景天、红参、黄精、白术的薄层图谱清晰,并且阴性无干扰.建立的鉴别方法简便,可靠,专属性强,重现性好,可用作参红补血颗粒的质量控制方法.