乙醇脱氢酶（ADH）产酶菌株的选育

从食醋生产企业的醋醅中采集样品,以乙醇为唯一碳源,用碳酸钙透明圈平板法分离出185株菌株,然后以产酸量和耐乙醇能力为标准,瓶发酵选育出20株ADH产酶菌株;A5-2产酸量为49.85 g/L,耐乙醇能力强,A5-2的菌种形态学和16S rDNA序列分析初步鉴定为巴斯德醋酸杆菌（ Acetobacter pasteurianus）;A5-2乙醇脱氢酶酶学性质研究表明：最适作用温度和pH分别为45℃和pH 4.0,具有一定的耐热性和良好的耐酸碱性;A5-2乙醇脱氢酶粗酶制备条件为硫酸铵饱和度70%~80%,回收率84%。     

发酵戊糖产酒精酵母菌株的选育

介绍了一种新的发酵戊糖产酒酵母菌种筛选方法并利用该方法筛选出一株性能优良的发酵戊糖酵母蓖株Z8,该菌株性能测试结果为：产酒精能力相当于发酵戊糖理论产量的60．0％,耐酒精能力14％（V／V）,在温度高达42℃的条件下仍能正常发酵,初步鉴定该菌株为管囊酵母（Pachysolen tannophilus)。     

耐热性毛霉菌株的筛选,鉴定及生理特性观测

从湖北、河南等地收集、分离的61株霉菌中,筛选得到一株可发酵生产腐乳的耐热性霉菌－H4菌株。经鉴定,H4菌株为毛霉（Mucorsp.）。在35℃条件下,该菌株在豆腐坯上生长、发酵良好,为目前报道的最耐热的腐乳生产用菌种之一。     

低双乙酰啤酒酵母菌株BEZ112的选育

以啤酒酿造生产菌株啤酒酵母(Saccharomyces cerevisiae)FB作为出发菌株,用甲基磺酸乙酯(EMS)诱变,经分离筛选得到一株优良的啤酒酵母菌株BEZ112。该菌株的絮凝性、发酵度、酒精度、发酵液的总酯和总高级醇的含量等特性保持了亲株的优良性状。但以12°Bx麦芽汁为培养基用500mL三角瓶在12℃下发酵,该菌株发酵至第4d,发酵液中的双乙酰含量达到峰值(0.291mg/L),比出发菌株FB发酵4d的峰值降低了30％,发酵至第8d,BEZ112发酵液中的双乙酰含量比出发菌株FB的降低了23％。以12°Bx麦芽汁为培养基用500L罐在12℃下发酵8d,BEZ112发酵液中的双乙酰含量(0.091mg/L)比出发菌株FB的(0.124mg/L)降低了27％。发酵得到的啤酒口感纯正清爽。     

适合甘蔗汁发酵高产酒精酵母的选育

目的:选育出适合发酵甘蔗汁生产燃料乙醇的高产酿酒酵母的菌株.方法:以酵母菌株 YS,作为出发菌株,将酶解破壁后获得的原生质体进行紫外诱变,通过初筛和复筛进行选育.结果:获得一株高产酒精的酿酒酵母突变株 YSs-1,该突变株发酵甘蔗汁的乙醇含量可达12.6%(V/V),较出发菌株的 11.6%(V/V)提高了 8.6%,其糖的转化率高达 94.5%,高于出发菌株的 87.0%.结论:通过 5 次连续传代培养后其突变株的乙醇产量保持稳定,表明该突变株完全可以用于发酵甘蔗汁生产燃料乙醇.     

优良啤酒酵母原生质体融合株GR5的构建及其发酵特性

以发酵度较高的非絮凝性的啤酒酵母菌株X6和发酵度较低、絮凝性较强的啤酒酵母菌株N1为亲本进行原生质体融合。用亚硝酸诱变原养型的菌株X6,经筛选得到一株需酪素水解物的营养缺陷型菌株X6~20。采用正交试验法分别优化菌株X6~20和N1的原生质体形成和再生的条件。用X6~20菌株的原生质体作为受体和热灭活的N1菌株原生质体作为供体进行融合。融合株经三角瓶发酵筛选,得到一株较优良的融合株GR5。该融合株的絮凝性较强(本斯值为2.7),以12°Bx麦芽汁为培养基,用500 L的发酵罐在12℃下发酵,发酵至第8 d菌株GR5的发酵度为69.2%,发酵液中的双乙酰含量为0.0498 mg/L、乙醛含量为6.34 mg/L,总高级醇含量为74.4mg/L。融合株GR5具有双亲的优点,发酵的啤酒风味较好,是一株具有工业应用前景的啤酒酿造酵母菌株。     

利用功能基因组学方法研究酿酒酵母乙醇生物合成的调控机理

酿酒酵母在发酵生产乙醇的过程中存在的主要问题是前期高浓度底物葡萄糖的抑制和后期高浓度产物乙醇的抑制。功能基因组学技术的发展为从基因组水平上系统研究酿酒酵母乙醇生物合成的调控机理提供可能。本研究模拟工业发酵的条件,对酿酒酵母实验菌株BY4743为遗传背景的116个单基因缺失菌株进行了乙醇发酵试验,以发现基因和乙醇发酵的关系。结果表明乙醇对菌体得率系数高于平均值30%以上的基因缺失株有20株,其中高于50%以上基因缺失株有5株;低于平均值30%以上的基因缺失株有11株,其中低于45%以上的有5株。本研究为从整个酿酒酵母基因组水平上系统研究乙醇生物合成的调控机理建立了研究方法,提供了可行性验证。     

利用原生质体融合技术构建耐酸絮凝性产乙醇酿酒酵母

为获得具有多种优良性状的高效乙醇生产菌株,以絮凝性酿酒酵母RHZ-1及耐酸耐温酿酒酵母SEB2为亲本,通过紫外诱变获得营养缺陷型标记菌株,并利用原生质体融合技术选育耐酸絮凝性酿酒酵母。通过对融合子的筛选获得一株优秀的耐酸絮凝性酿酒酵母菌株RS-1;该菌株在30℃,pH2.2,15%YPD条件下发酵24 h,乙醇产生量为47.87 g/L,糖消耗速率和基于糖消耗的乙醇收率分别比亲本菌株RHZ-1提高了19.5%和9.8%。在35℃,p H2.2,15%YPD条件下发酵48 h,乙醇产生量为38 g/L,糖消耗速率和乙醇收率分别比亲本菌株RHZ-1提高了46.8%和21.6%。结果表明,获得的菌株可为提高燃料乙醇的生产效率奠定基础。     

一株产环糊精葡萄糖基转移酶的地衣芽孢杆菌的选育、产酶条件及酶学特性

从土壤分离物中筛选到一株环糊精葡萄糖基转移酶 (CGTase)产生菌 4 0 3,96h发酵酶活为 0 95U mL。经紫外辐射和硫酸二乙酯复合诱变而获得突变株CLS4 0 3,96h发酵酶活达 1 36U mL ,提高 4 3%。该突变菌株被鉴定为地衣芽孢杆菌 (Bacilluslicheniformis) ,产CGTase的最佳碳源为可溶性淀粉 ,最佳氮源为硝酸铵 ,最适初始pH为 6 5 ,最适培养温度为 35℃ ,发酵期间CGTase的产生高峰 (第 96h)滞后于菌体生物量高峰 (第 4 8h) 2d。菌株所产CGTase的最适反应pH为 6 0 ,最适温度为 5 5℃ ,在pH 6 0～ 7 5间和 5 0℃下保持 1h后的剩余酶活均达 90 %以上 ;酶液中适量添加Ca2 能大幅提高CGTase在 5 5℃下的稳定性。经高效液相色谱分析 ,CGTase作用于淀粉后的产物以α 环糊精为主 ,β 环糊精为次 ,二者比例为 2 4 7∶1,环糊精总产率达 2 9 8% ,但产物中不含γ 环糊精     

猪、牛血固态发酵生产蛋白质饲料的研究

从１２株曲霉属（Ａｓｐｅｒｇｉｌｌｕｓ）食品生产菌中筛选出一株能发酵降解猪、牛血的ＲＡ＿３菌株,并对该菌株用于猪、牛血固态发酵生产蛋白质饲料的工艺进行了研究。采用新鲜猪血与麸皮按１：１的比例混合发酵４ｄ（前、后酵各两天）,所得猪、牛血发酵蛋白质饲料的粗蛋白含量达３１％—３５％,明显地提高了猪、牛血的可消化性和适口性,用于产蛋鸡等家禽饲养具有显著增产效果。     

Xylose and cellobiose fermentation to ethanol by the thermotolerant methylotrophic yeast Hansenula polymorpha

Wild-type strains of the thermotolerant methylotrophic yeast Hansenula polymorpha are able to ferment glucose, cellobiose and xylose to ethanol. H. polymorpha most actively fermented sugars to ethanol at 37 degrees C, whereas the well-known xylose-fermenting yeast Pichia stipitis could not effectively ferment carbon substrates at this temperature. H. polymorpha even could ferment both glucose and xylose up to 45 degrees C. This species appeared to be more ethanol tolerant than P. stipitis but more susceptible than Saccharomyces cerevisiae. A riboflavin-deficient mutant of H. polymorpha increased its ethanol productivity from glucose and xylose under suboptimal supply with riboflavin. Mutants of H. polymorpha defective in alcohol dehydrogenase activity produced lower amounts of ethanol from glucose, whereas levels of ethanol production from xylose were identical for the wild-type strain and the alcohol dehydrogenase-defective mutant.     

Breeding of yeast strains able to grow at 42 degrees C

Saccharomyces cerevisiae strain 2-39/10A is able to ferment alcohol at 42 degrees C. The ability of various yeast strains, including 2-39/10A, to grow at high temperatures was compared. The strain 2-39/10A was able to grow at 42 degrees C and the high temperature growth was found to be governed by more than one gene. The yeast strains that can grow at 42 degrees C were bred by crossing the haploid strains, which are inherently unable to grow at high temperatures.     

Potenytial cost savings for fuel ethanol production by employing a novel hybrid yeast strain

Summary A hybrid yeast (Labatt culture collection strain 1393) was investigated for its ability to ferment a corn mash with reduced concentrations of added glucoamylase. It was found that glucoamylase additions could be decreased by as much as 50 percent. This reduction could represent significant cost savings in the production of fuel ethanol.     

酵母菌属间原生质体融合构建高温酵母菌株

酿酒酵母(Saccharomyces cerevisiae) A001和克鲁维酵母(Kluyveromyces sp.) Y034属间原生质体融合构建高温酵母菌株。对制备高再生活性原生质体及融合子细胞形态、生理化特征、同工酶性质、遗传稳定性和高温发酵等方面进行了研究。结果表明,融合子AY023和AY680遗传性能稳定,表达了双亲优良性状,获得了在45℃培养条件下产酒率7.4%的属间融合菌株,是目前已见文献报道的产酒率最高的高温(45℃)酵母菌株。     

Effect of the petite mutation on maltose and alpha-methylgucoside fermentation inSaccharomyces cerevisiae.

Summary Several hundred petite mutants were isolated from yeast strains of different genotype to examine the effect of the petite mutation on maltose and alpha-methylglucoside fermentation. In most cases petite mutants isolated retain the ability to ferment maltose and alpha-methylglucoside, although at a slower rate. In one strain (1403-7A), however, the ability to ferment alpha-methylglucoside is completely lost in all petite mutants isolated from this strain. It is suggested that mitochondrial factors may be involved in the utilization of alpha-methylglucoside in strain 1403-7A.     

Influence of invertase activity and glycerol synthesis and retention on fermentation of media with a high sugar concentration by Saccharomyces cerevisiae.

In the past, the fermentation activity of Saccharomyces cerevisiae in substrates with a high concentration of sucrose (HSuc), such as sweet bread doughs, has been linked inversely to invertase activity of yeast strains. The present work defines the limits of the relationship between invertase activity and fermentation in hyperosmotic HSuc medium. Fourteen polyploid, wild-type strains of S. cerevisiae with different invertase levels gave a similar ranking of fermentation activity in HSuc and in medium in which glucose and fructose replaced sucrose (HGF medium). Thus, invertase is unlikely to be the most important determinant of fermentation in sweet doughs. Yeasts produce the compatible solute-osmoprotective compound glycerol when exposed to hyperosmotic environments. Under low sugar concentrations (and nonstressing osmotic pressure), there was no correlation between glycerol and fermentation activities. However, there was a strong correlation between the ability of yeasts to ferment in HSuc or HGF medium and their capacity to produce and retain glycerol intracellularly. There was also a strong correlation between intracellular glycerol and fermentation activity of yeasts in a medium in which the nonfermentable sugar alcohol sorbitol replaced most of the sugars (HSor), but the ability to produce and retain glycerol was greater when yeasts were incubated in HGF medium under the same osmotic pressure. The difference between the amounts of glycerol produced and retained in HSor and in HGF media varied with strains. This implies that high fermentable sugar concentrations cause physiological conditions that allow for enhanced glycerol production and retention, the degree of which is strain dependent. In conclusion, one important prerequisite for yeast strains to ferment media with high concentrations of sugar is the ability to synthesize glycerol and especially to retain it.     

协同诱变法选育虾青素高产优良酵母菌株

以红法夫酵母(Phaffia rhodozyma)野生型菌株GH1为研究对象,选育虾青素高产优良酵母菌株,并初步研究其生长特性。对野生型菌株GH1用紫外线(UV)和亚硝基胍(NTG)协同诱变,用抗霉素A筛选,选育出虾青素高产突变菌株GH1-7.1。突变菌株GH1-7.1的虾青素最高产量达1200μg/gDCW,比野生菌株GH1的虾青素最高产量271μg/gDCW高出4倍,并且生长加快,达到最高生物量和最高虾青素产量的时间比野生菌株缩短了24h;野生菌株GH1的最适生长温度为20℃,高于28℃则不生长,而突变菌株GH1-7.1的最适生长温度为28～30℃,比野生菌株GH1提高8～10℃。首次采用协同诱变的方法成功选育了虾青素高产酵母菌株,并且生长周期短,最适的生长温度提高,是适宜南方高温环境发酵工程应用的优良菌株。     

The impact of brewing yeast cell age on fermentation performance,attenuation and flocculation

Individual cells of the yeast Saccharomyces cerevisiae exhibit a finite replicative lifespan, which is widely believed to be a function of the number of divisions undertaken. As a consequence of ageing, yeast cells undergo constant modifications in terms of physiology, morphology and gene expression. Such characteristics play an important role in the performance of yeast during alcoholic beverage production, influencing sugar uptake, alcohol and flavour production and also the flocculation properties of the yeast strain. However, although yeast fermentation performance is strongly influenced by the condition of the yeast culture employed, until recently cell age has not been considered to be important to the process. In order to ascertain the effect of replicative cell age on fermentation performance, age synchronised populations of a lager strain were prepared using sedimentation through sucrose gradients. Each age fraction was analysed for the ability to utilise fermentable sugars and the capacity to flocculate. In addition cell wall properties associated with flocculation were determined for cells within each age fraction. Aged cells were observed to ferment more efficiently and at a higher rate than mixed aged or virgin cell cultures. Additionally, the flocculation potential and cell surface hydrophobicity of cells was observed to increase in conjunction with cell age. The mechanism of ageing and senescence in brewing yeast is a complex process, however here we demonstrate the impact of yeast cell ageing on fermentation performance.     

Involvement of thermophilic archaea in the biocorrosion of oil pipelines

Two thermophilic archaea, strain PK and strain MG, were isolated from a culture enriched at 80°C from the inner surface material of a hot oil pipeline. Strain PK could ferment complex organic nitrogen sources (e.g. yeast extract, peptone, tryptone) and was able to reduce elemental sulfur (S°), Fe(3+) and Mn(4+) . Phylogenetic analysis revealed that the organism belonged to the order Thermococcales. Incubations of this strain with elemental iron (Fe°) resulted in the abiotic formation of ferrous iron and the accumulation of volatile fatty acids during yeast extract fermentation. The other isolate, strain MG, was a H(2) :CO(2) -utilizing methanogen, phylogenetically affiliated with the genus Methanothermobacter family. Co-cultures of the strains grew as aggregates that produced CH(4) without exogenous H(2) amendment. The co-culture produced the same suite but greater concentrations of fatty acids from yeast extract than did strain PK alone. Thus, the physiological characteristics of organisms both alone and in combination could conceivably contribute to pipeline corrosion. The Thermococcus strain PK could reduce elemental sulfur to sulfide, produce fatty acids and reduce ferric iron. The hydrogenotrophic methanogen strain MG enhanced fatty acid production by fermentative organisms but could not couple the dissolution Fe° with the consumption of water-derived H(2) like other methanogens.     

休哈塔假丝酵母乙醇发酵性能的研究

木糖的高效发酵是制约纤维素燃料乙醇生产的技术瓶颈之一,高性能发酵菌种的开发是本领域研究的重点。以木糖发酵的典型菌株休哈塔假丝酵母为材料,研究氮源配比、葡萄糖和木糖初始浓度、葡萄糖添加及典型抑制物等因素对其木糖利用和乙醇发酵性能的影响规律。结果表明,硫酸铵更适宜于木糖和葡萄糖发酵产乙醇。在摇瓶振荡发酵条件下,该酵母可发酵164.0 g/L葡萄糖生成61.9 g/L乙醇,糖利用率和乙醇得率分别为99.8%和74.0%;受酵母细胞膜上转运体系的限制,对木糖的最高发酵浓度为120.0 g/L,可生成45.7 g/L乙醇,糖利用率和乙醇得率分别达到94.8%和87.0%。休哈塔假丝酵母发酵木糖的主要产物为乙醇,仅生成微量的木糖醇;添加葡萄糖可促进木糖的利用;休哈塔假丝酵母在葡萄糖发酵时的乙酸和甲酸的耐受浓度分别为8.32和2.55 g/L,木糖发酵时的乙酸和甲酸的耐受浓度分别为6.28和1.15 g/L。