“高效酒精生产酵母工程菌技术成果发布会”在南宁召开

【本刊讯】由广西食品工业协会和广西区经贸委糖业处组织的“高效酒精生产酵母工程菌技术成果发布会”于 8月 2日在南宁广西科技活动中心召开。来自区内 6 0多家制糖、酒精企业 ,相关学校和科研单位的 12 0多名专家及工程技术人员参加了会议。　　由清华大学和云南大学联合攻关完成的这一最新技术成果是一支耐高糖、耐高酒精、高产率的酵母工程菌 (酵母1912 )。　　一般的酵母菌在碳源充足且无氧的条件下可生产乙醇 ,在碳源不足时 ,会把乙醇作为碳源消耗掉 ,而且乙醇会在乙醇脱氢酶 作用下生成乙醛。该新技术用分子生物学方法将乙醇脱氢酶 …     

无酵母生淀粉酒精发酵的研究

利用根霉—3(Rhizopus—3)麸曲进行无酵母生淀粉酒精发酵研究。以生玉米淀粉为原料,无酵母酒精发酵醪液酒度8.5％(v/v,20℃),淀粉利用率84.87％。研究了该工艺过程中的一些条件。发现发酵终产物乙醇对生淀粉糖化酶的活性有抑制作用。生淀粉的糖化是该过程的限速步骤。15gRhizopus—3鲜曲的酒化力与10ml酒母相当。发酵时添加一定量的α-淀粉酶、纤维素酶或果胶酶有协同作用,可提高淀粉利用率。同时探讨了无酵母生淀粉酒精发酵的机制,认为选育具有高活性生淀粉糖化酶和酒化酶等复合酶系的菌种是关键问题。     

利用原生质体融合技术构建梨酒酵母工程菌

以菌株酿酒酵母Saccharomyces cerevisiae YDJ05及产香酵母Issatchenkia orientalis YS03为融合亲本X和Y,通过原生质体融合技术构建适合梨酒酿造的酵母工程菌,研究结果表明:利用EMS诱变亲本菌株Y,得到了一株精氨酸营养缺陷型菌株,亲本菌株X和Y采用蜗牛酶液在35℃下处理100min,得到菌株X、Y的原生质体融合率分别为93.6％、94.2％,再生率分别为27.8％、31.6％.以加热的方式灭活亲本菌株X,灭活时间为14min.在以PEG为促融剂的条件下对两株菌进行原生质体融合,经过优选得到融合子D J02,其产酒精率、产香率等指标最优,分别达到了9.87％、0.37g/L.     

利用原生质体融合技术构建梨酒酵母工程菌

以菌株酿酒酵母Saccharomyces cerevisiae YDJ05及产香酵母Issatchenkia orientalis YS03为融合亲本X和Y,通过原生质体融合技术构建适合梨酒酿造的酵母工程菌,研究结果表明:利用EMS诱变亲本菌株Y,得到了一株精氨酸营养缺陷型菌株,亲本菌株X和Y采用蜗牛酶液在35℃下处理100min,得到菌株X、Y的原生质体融合率分别为93.6%、94.2%,再生率分别为27.8%、31.6%。以加热的方式灭活亲本菌株X,灭活时间为14min。在以PEG为促融剂的条件下对两株菌进行原生质体融合,经过优选得到融合子DJ02,其产酒精率、产香率等指标最优,分别达到了9.87%、0.37g/L。      

热带假丝酵母在木薯淀粉酒精废液治理中的应用研究

利用热带假丝酵母治理木薯淀粉酒精废液,以COD值的去除率为指标,探索不同条件对治理效果的影响,小试及中试实验表明:调节处理液BOD5∶N∶P比为100∶1∶0.2,其中N或P不足需在废液中添加尿素或磷酸盐,调节接种pH值为5.3,温度30℃,溶氧DO值3 mg/mL,接种量1‰,可以在约100 h内使COD值由3×104 mg/L-4×104 mg/L降至2000 mg/L以下,且废液的色值有明显的降低.     

影响酒精酵母产生乙醇耐性的因素

乙醇对细胞的抑制主要表现在对生长率、发酵率、糖分解酶、膜势能的抑制及膜磷脂的裂解。该文主要阐述了细胞质膜不饱和脂肪酸、曲霉蛋白脂、特定的崮醇及加氧作用对酒精酵母产生乙醇耐性的影响。     

高温和高酒精浓度下的酵母特性

在酒精生产中，应用嗜热微生物有很多优势。酒精浓度和温度是影响酵母发酵的2个重要因素，当2个因素相互作用时，随着温度和酒精浓度的上升，使细胞中脂肪酸的组成及热冲击蛋白发生变化，酵母的耐受力下降。     

半乳糖苷酶基因重组酵母的酒精发酵

半乳糖苷酶催化半乳糖苷键的水解,包括α-半乳糖苷酶和β-半乳糖苷酶。就半乳糖苷酶的应用研究,尤其是半乳糖苷酶遗传修饰酵母在酒精发酵中的作用进行了简要综述。     

固定化酵母发酵技术及其在糖蜜酒精生产应用中的经济效益

固定化酵母发酵技术，解决厂传统游离酵母发酵生产酒精出现容易感染杂菌酸败、发酵水平不高、成熟醪残糖高的问题。该技术应用在糖蜜酒精生产中，发酵液中酵母数达1.6～2.0亿／mL，，成熟酿酒分稳定在9.5×10－2～11×10－2、残糖在1.7×10－2～1.8×10－2，它操作简单、粗放、操作条件弹性大、发酵速度快、提高生产能力、成熟醑残糖低，从而创造了明显的经济效益。     

CAMBRIDGE PRIZE LECTURE DEVELOPING NEW STRAINS OF YEAST*

Genetic engineering or recombinant DNA technology is now routinely applied to the construction and development of new strains of brewing yeast. This is a direct consequence of the power of the technology which facilitates the modification, introduction and stable maintenance of specific genes in brewing yeast, without compromising the intrinsic brewing properties of the yeast itself. The way in which gene technology has been applied to the development of new strains of Bass yeast is briefly illustrated by the provision of plasmid-based systems for ensuring the stable maintenance of recombinant genes, the construction of amylolytic and β-glucanolytic yeast and the design and development of genetic systems for enhancing the value of waste brewers yeast. Commercial and regulatory issues are discussed.     

基因重组技术在啤酒酵母育种、改进啤酒风味方面的应用

随着DNA重组技术的发展，新型啤酒酵母的定向育种工作迅速发展。着重介绍了基因重组技术在育种、去除异杂味和改进啤酒风味方面的应用。     

营养盐加量对酵母发酵的影响初探

研究了玉米淀粉浆在不同添加比例的营养盐1#、2#、3#、4#、5#液化、糖化,在发酵22h、46h、60h进行发酵试验对比,将能使酵母生长状态好,酵母数多、出芽率高、产酒率高的样品应用到生产中。     

Genetically-modified brewing yeasts for the 21st century. Progress to date

Academic studies and traditional breeding of yeasts depend upon their sporulation lifestyle. The strains used have been specially selected to sporulate readily and to mate producing new yeast types. Unfortunately brewing yeast strains do not behave in this way. They sporulate poorly, any spores which are formed are usually non-viable and any haploid strains produced are invariably non-maters. Only in recent years, with the development of recombinant-DNA techniques, has the specific breeding of new brewing yeast strains become widespread. Strains have been produced with the ability to ferment a wider range of carbohydrates, with altered flocculation properties and which produce beers with modified flavours. Many have been tested on the pilot scale and one, an amylolytic brewing yeast, has received approval for commercial use.     

Identification of major ADH genes in ethanol metabolism of Pichia pastoris

The methylotrophic yeast Pichia pastoris (syn. Komagataella phaffii) is a successful host widely used in recombinant protein production. The widespread use of a methanol-regulated alcohol oxidase 1 (AOX1) promoter for recombinant protein production has directed studies particularly about methanol metabolism in this yeast. Although there is comprehensive knowledge about methanol metabolism, there are other mechanisms in P. pastoris that have not been investigated yet, such as ethanol metabolism. The gene responsible for the consumption of ethanol ADH2 (XM_002491337, known as ADH3) was identified and characterized in our previous study. In this study, the ADH genes (XM_002489969, XM_002491163, XM_002493969) in P. pastoris genome were investigated to determine their roles in ethanol production by gene disruption analysis. We report that the ADH900 (XM_002491163) is the main gene responsible for ethanol production in P. pastoris. The ADH2 gene, previously identified as the only gene responsible for ethanol consumption, also plays a minor role in ethanol production in the absence of the ADH900 gene. The investigation of the carbon source regulation mechanism has also revealed that the ADH2 gene exhibit similar expression behaviours with ADH900 on glucose, glycerol, and methanol, however, it is strongly induced by ethanol.     

发酵木糖产酒精酵母菌的初步研究

采用稀释平板法及划线分离法从自然环境中筛选获得120株形态特征不尽相同的酵母菌,然后通过发酵木糖、葡萄糖试验获得6株能利用木糖为唯一碳源生长的酵母菌株,其中有1株分解木糖产乙醇能力较佳,其发酵条件为:96r/min摇瓶发酵、温度为30℃、木糖浓度为3.0%时木糖转化率最高达7.1%。     

固定化酵母发酵产酒精载体选择的研究

以海藻酸钙和甘蔗块为载体固定酵母细胞,进行蔗汁和废糖蜜酒精发酵。结果表明,以甘蔗汁为发酵培养基时甘蔗块固定化酵母发酵液中平均残糖锤度(20℃)比海藻酸钙包埋酵母发酵低0.36,酒精平均体积分数比海藻酸钙包埋酵母发酵高0.20%;以废糖蜜为发酵培养基时甘蔗块固定化酵母发酵液中平均残糖锤度(20℃)比海藻酸钙包埋酵母发酵低0.43,酒精平均体积分数比海藻酸钙包埋酵母发酵高0.23%,显示出甘蔗块固定化法酵母发酵优于海藻酸钙包埋法固定化酵母。此外,甘蔗汁培养基与废糖蜜培养基对总体发酵效果的影响非常接近,但综合考虑甘蔗汁与废糖蜜的成本,废糖蜜是工业发酵生产乙醇用培养基的更优选择。     

The influence of vitamin E supplementation on yeast fermentation

Ethanol is a well‐known toxic metabolite of yeast, affecting cell growth, and it is a major factor responsible for reduced ethanol production. Therefore, yeast strains that can withstand high ethanol concentrations are highly desirable. The effects of vitamin E supplementation and enhanced cell membrane fluidity in ethanol fermentations were studied. The results showed that ethanol tolerance was significantly improved by vitamin E supplementation, which correlated with the increased level of polyunsaturated fatty acids. The data showed that, after 0.1 g L^?1 vitamin E was added to the highest ethanol concentration, one could attain 118.7 g L^?1, in contrast to 106.4 g L^?1. The experimental results indicated that the increase in vitamin E suppressed unsaturated fatty acid oxidation, resulting in enhanced ethanol tolerance and increased production yield. Copyright © 2016 The Institute of Brewing & Distilling     

利用马铃薯淀粉生产的废水及废渣发酵制备蛋白饲料

以马铃薯淀粉生产的废水及废渣为原料,采用微生物发酵的方法,制备高附加值的蛋白饲料,同时降低废水的COD值,达到综合利用的目的。经试验筛选得到1株酵母,并确定了蛋白饲料的制备条件:废水中薯渣添加量20%、pH自然、温度28℃、接种量10%、发酵时间72 h。在适宜条件下,制备的蛋白饲料蛋白含量达37.40%,废水COD降低72.29%。     

酵母流加发酵生产中乙醇浓度的在线测量

研制了乙醇浓度在线监测仪 ,并对其在酵母流加生产中的应用情况进行了考察 .结果表明 ,采用乙醇浓度反馈流加培养方式 ,细胞产率和发酵活力可分别达到 0 .4 1 6g/ g和 980～ 1 1 0 0mL ,显示出良好的应用前景 .