快中子诱变所得黑曲霉变异株UV-11-NF83的特性研究

产糖化酶的黑曲霉(Aspergillus niger)变异株UV-11(AS3.4309),通过快中子处理诱变,获得一株具有高活力糖化酶的新变异株UV-11-NF83,产酶活力从3600u/ml提高到7000u/ml。培养基配方为玉米粉:豆饼粉:麸皮=10:4:3时,酶活力达13000u/ml。该变异株产酶pH在3-4之间。它的发酵液不仅具有糖化酶活力高的特点,而且具有a-淀粉酶、酸性蛋白酶、葡萄糖转苷酶低的特点,糖化淀粉的DE值达98％以上。 我们曾报道了“快中子对黑曲霉(Asptrgillus niger)变异株UV-11(AS3.4309)产糖化酶的诱变效应”的研究情况。在这个基础上,我们又用快中子诱变获得了一株比变异株UV-11产酶能力提高90.1%的新变异株UV-11-NF83。现报道如下。     

固定化己酸菌新材料研究报告

简要介绍了上世纪八十年代白酒行业微生物细胞固定化技术研究和应用情况。天津酿酒厂和天津啤酒厂合作,研究成功PVA和颗粒活性炭两种己酸菌固定化新材料。颗粒活性炭通过生产规模试验,产酸可达620mg/100m L以上,比传统方法提高两倍,比国内最先用于固定化细胞的琼脂包埋法提高29.4%,载体使用次数提高近两倍,达29次以上。细胞固定化技术,极大的简化了己酸菌培养工艺,降低发酵液成本,对提高津酒和同一类浓香型白酒质量,展示出很大潜力和美好前景,试验中还与南开大学合作,拍了电子显微镜照片,可清楚地看到菌体形态。     

固定化果胶酶产生菌澄清果汁研究

以多孔聚氨酯泡洒（PUF）固定化果胶酶产生菌黑曲霉P－6021可以实现菌丝体重复发酵产酶,重复5个批次,菌体数目增多,产酶量上升,发酵液酶活达以664．4U／ml.以PUF固定化黑曲霉P－6021进行了同时产酶澄清苹果汁试验,以苹果汁基质发酵12h后,产酶量可达到643．2u/ml,苹果汁基本澄清,透光率提高,粘度降低,表明固定化黑曲霉摇瓶间隙同时产酶澄清苹果汁工艺是可行的。     

固定化细胞生产糖化酶——Ⅱ、发酵条件与半连续发酵试验

黑曲霉As·3.4309的孢子用海藻酸钙凝胶固定化,制成固定化细胞胶粒,用于生产糖化酶的研究。 固定化黑曲霉细胞,产糖化酶的最适温度为32℃,培养基的pH值以5.0为宜。培养基中碳源和氮源的配比对糖化酶的生产有显著的影响。 固定化细胞半连续发酵生产糖化酶的研究结果表明,第一次发酵的周期为120小时左右,发酵液中糖化酶活力接近游离细胞发酵的水平。第二次以后发酵的周期缩短到60小时以下,而产酶水平随着反复使用次数的增加不断提高,最高时达到游离细胞产酶的130％以上。固定化细胞可以连续使用30天。     

生物反应器发酵海藻功能食醋的研究(Ⅰ)——多元混菌固定发酵海藻酒醪

以海带为主要原料，采用PVA固定化酿酒酵母、产香酵母和醋酸菌双轮发酵酿造海藻功能食醋进行了研究。对游离细胞与固定化细胞与固定化细胞的分批发酵和连续发酵产酒的动力学进行了研究并建立了相应的发酵动力学方程。结果表明：酿酒酵母和产香酵母二种菌种菌量的最佳配比为4：1，发酵温度20℃，固定化细胞分批发酵和连续发酵凝胶粒的充填系数分别为O．25和O．5，游离混合细胞的发酵时间为7d，固定化细胞连续发酵稀释速率0．12／h其发酵时间为0．5d左右。经160d连续发酵实验，PVA固定化细胞粒子的机械强度良好。     

固定化根霉细胞产生糖化酶的研究

选取精化用菌Rh delemer3．5进行细胞固定化,经增殖后于液体培养基中进行好气性发酵,产生糖化酶实验结果表明,海藻酸钙是适宜的固定化载体,相同条件下固定化细胞的产酶能力较游离细胞高60~80%,并可连续使用300小时以上。电子显微镜观察表明:根霉在海藻酸钙凝胶内生长良好,保持较长的稳定期,处于不断产酶状态。     

混合多菌种固定化发酵海带酒的研究

采用固定化酿酒酵母和产香酵母发酵海带,酿造海带酒。对游离细胞与固定化细胞的分批发酵和连续发酵产酒的动力学进行了研究并建立了相应的发酵动力学方程。实验结果表明:酿酒酵母和产香酵母二种菌种菌量的最佳配比为4∶1,发酵温度20℃,固定化细胞分批发酵和连续发酵凝胶粒的充填系数分别为0.25和0.5,游离混合细胞的发酵时间为7d,固定化细胞连续发酵稀释速率0.12/h其发酵时间为0.5d左右。经160d连续发酵实验,PVA固定化细胞粒子的机械强度良好.     

优良生淀粉酶产生菌Asp.882的研究第Ⅱ报——酶性质及动力学初探

报导了用新方法选育的优良生淀粉糖化酶产生菌Asp.882的酶性质及动力学情况。实验证明它对多种生淀粉有较强的分解能力;顺序是:糯米>小米>大米>小麦>木薯>玉米>甘薯>马铃薯。酶最适反应pH为3.0～4.0,45℃保温30分钟不失活,2％葡萄糖对酶有抑制作用。酶作用于大米粉的米氏常数是1.3％。酶曲产生淀粉糖化酶达230～245u/g(pH3.6,40℃),蛋白酶3000～4000u/g,液化酶6～7u/g,纤维素酶20～25u/g。□(谢敏)     

共固定化多菌种混合发酵生产苹果醋的研究

以苹果或苹果加工厂下脚料为主要原料,对采用多菌种共固定化活细胞混合发酵生产苹果醋进行了研究,实验表明,固定化多菌种发酵生产苹果醋的最佳工艺是将酿酒酵母,产香酵母,乳酸菌共同固定,按与发酵液1：7－1：8的比例,加入到总糖为12％的苹果汁发酵液中,反应温度控制在30度,然后再把固定好的醋酸菌加入到已经酒化好的发酵液中,进行醋酸发酵,反应温度控制在34－36度。     

优良生淀粉酶产生菌Asp.882的研究第1报——小型酒精发酵试验

本文报导新选育的优良生淀粉酶产生菌Asp.882用于酒精发酵小型试验的研究情况。该菌酶曲含生淀粉酶190～240u/g,液化酶6～7u/g,蛋白酶3000～4000u/g,纤维素酶20～25u/g,其复合酶系能适于多种淀粉原料发酵。当它与酵母共酵生产酒精时,其用酶量约10u/g左右,加水比例为1:2.5～3.3,33℃发酵72～96小时,淀粉利用率达90％左右,酒度10％～14％(V/V),残糖1.25％～1.50％。而且酒糟易过滤,具有较大的应用价值。     

啤酒酵母的基因改良研究动态

近年来 ,利用基因工程进行酵母的育种在发酵广谱碳水化合物、提高糖化效率 ,改良酵母凝聚特性和改善啤酒风味方面取得了很大成绩。基因重组菌株将逐步应用到生产实践中。     

The natural diversity and ecology of fission yeast

While the fission yeast is a powerful model of eukaryote biology, there have been few studies of quantitative genetics, phenotypic or genetic diversity. Here I survey the small collection of fission yeast diversity research. I discuss what we can infer about the ecology and origins of Schizosaccharomyces pombe from microbiology field studies and the few strains that have been collected.     

Construction of an insertion marker collection of Sz. japonicus (IMACS) for genetic mapping and a fosmid library covering its genome

Measuring relative genetic distances is one of the best ways to locate genetic loci. Here we report the construction of a strains set for genetic mapping in Schizosaccharomyces japonicus, which belongs to the genus Schizosaccharomyces together with the well‐studied fission yeast Sz. pombe. We constructed 29 strains that bear a positive‐negative selection marker at different loci. The marker was inserted every 500 kb in the genome of Sz. japonicus. Each marker thus becomes a ‘scale mark’ of a chromosome that behaves like a yardstick. By determining the genetic distances from the inserted markers, the relative location of a genomic mutation can be determined. We also constructed a fosmid library that covers an entire genome of Sz. japonicus. These tools together would facilitate identification and cloning of the gene. Copyright © 2012 John Wiley & Sons, Ltd.     

IFA在酿酒污染野生酵母快速检测中的应用

用荧光抗体技术进行快速检测,方法简便、灵敏、快速。用三种混合血清可以检测出常见全部污染野生酵母。该技术在工厂中应用结果表明,酿酒种酵母中野生酵母污染现象是存在的,而且随着种酵母使用代数的增加而越趋严重。     

Karyotyping of yeast strains of several genera by field inversion gel electrophoresis

Field inversion gel electrophoresis has been used to improve the resolution of the large chromosomes (greater than 1000 kb) present in Saccharomyces kluyveri and in several genera of yeasts other than Saccharomyces cerevisiae, and thus establish more accurately the electrophoretic karyotype of these yeasts. Field inversion gel electrophoresis has also been used to demonstrate the presence of chromosome length polymorphisms in several of the yeasts studied. By Southern blotting techniques the greater degree of relatedness of S. kluyveri and Kluyveromyces lactis to S. cerevisiae, as compared to that of the other genera of yeasts studied, has been established.     

Effect of Growth Media and Strains on Structural Stability in Small Chromosomes (Chromosome I,VI and III) of Bottom‐Fermenting Yeast

The PFGE analysis results of 50 clones, each isolated from cultures of two lager strains (P and Q), after passage of 700 generations in wort or YEPD, showed that small chromosomal DNAs (I, VI and III) are susceptible to changes during successive cultivation. These changes may be strain‐dependent (P > Q) and the media may also affect the instability in the chromosomal DNAs (YEPD > wort).     

Impact of dried,creamed and cake supply formats on the genetic variation and ethanol tolerance of three Saccharomyces cerevisiae distilling strains

Scotch whisky fermentations typically employ high‐gravity fermentation practices to maximize product formation and to minimize both energy and water inputs. This approach increases ethanol concentrations at the end of fermentation, creating stressful conditions for the yeast. In this work we examined the relative tolerance of four Saccharomyces cerevisiae distilling yeast strains, supplied in dried, creamed, cake or slurry format, to ethanol under CO₂‐induced anaerobic conditions. The cells were assessed for their capacity to recover and grow on inhibition spot plates and to maintain cell viability in ethanol‐dosed suspensions. Variations in ethanol tolerance were observed between strains and between the same strain supplied in different formats. The creamed yeast format typically exhibited a higher tolerance to ethanol. One possible explanation for this observation is that cells surviving the dehydration and rehydration process might incur sub‐lethal genome damage. Thus the genetic integrity of the most ethanol‐tolerant strain was assessed as a function of supply format (two dried and one creamed). The mitochondrial DNA was examined using mitochondrial restriction fragment length polymorphism and the chromosomal DNA using pulsed field gel electrophoresis and polymerase chain reaction with both ITS and delta‐specific primers. In one dried yeast sample, genetic integrity was compromised, highlighting the requirement for yeast intake quality assurance programmes. Copyright © 2012 The Institute of Brewing & Distilling     

A set of genetic markers for the chromosomes of the imperfect yeast Arxula adeninivorans

The nuclear genome of the anamorphic yeast Arxula adeninivorans was analysed by benomyl-induced haploidization of parasexual hybrids marked with 32 auxotrophic mutations and pulsed field gel electrophoresis followed by DNA hybridization. Twenty-seven genes have been arranged into four linkage groups by haploidization, 15 genes belong to group 1, six to group 2, and three each to groups 3 and 4. Five genes could be localized by DNA hybridization on three out of four separated chromosomes. The gene LYS2 of the largest linkage group 1 and the 25S rDNA were identified on the largest chromosome, the GAA and the TEF1 gene on chromosome 2, and the ILV1 gene of linkage group 4 on the smallest chromosome.     

A set of genetically diverged Saccharomyces cerevisiae strains with markerless deletions of multiple auxotrophic genes

Genome analysis of over 70 Saccharomyces strains revealed the existence of five groups of genetically diverged S. cerevisiae wild‐type isolates, which feature distinct genetic backgrounds and reflect the natural diversity existing among the species. The strains originated from different geographical and ecological niches (Malaysian, West African, North American, Wine/European and Sake) and represent clean, non‐mosaic lineages of S. cerevisiae, meaning that their genomes differ essentially by monomorphic and private SNPs. In this study, one representative strain for each of the five S. cerevisiae clean lineages was selected and mutated for several auxotroph genes by clean markerless deletions, so that all dominant markers remained available for further genetic manipulations. A set of 50 strains was assembled, including eight haploid and two diploid strains for each lineage. These strains carry different combinations of leu2?0, lys2?0, met15?0, ura3?0 and/or ura3?::KanMX‐barcoded deletions with marker configurations resembling that of the BY series, which will allow large‐scale crossing with existing deletion collections. This new set of genetically tractable strains provides a powerful tool kit to explore the impact of natural variation on complex biological processes. Copyright © 2013 John Wiley & Sons, Ltd.