SPHEROPLAST FUSION OF BREWER'S YEAST STRAINS

Spheroplasts of brewing polyploid yeast strains have been successfully fused with spheroplasts of haploid yeast strains. After regeneration of the cell wall, stable fusion recombinants were isolated. Genetic analysis of these recombinants revealed that they contained the genotype of both parents, sporulated well with each ascus containing four spores and were indeed diploid. Spheroplast fusion thus affords a means to genetically analyse brewing yeast strains, such an analysis having been difficult if not impossible by conventional hybridization techniques.     

CONSTRUCTION OF YEAST STRAINS FOR THE PRODUCTION OF LOW-CARBOHYDRATE BEER

By way of somatic hybridization of a lager brewing strain with Saccharomyces diastaticus, a hybrid was constructed, which is suitable for the production of low carbohydrate beer. The hybrid character of the fusion product was confirmed by physiological tests and segregation analyses, as well as, on a molecular basis, by OFAGE (TAFE) and Ty-hybridization.     

Sterility (ste) genes of Schizosaccharomyces pombe

In previous experiments of Girgsdies (1982), eight sterile (ste) mutants of Schizosaccharomyces pombe did not sporulate when fused with h⁺ or h^? protoplasts. We succeeded in achieving sporulation with these mutants. Two hitherto unknown ste genes, ste7 and ste8, were found.     

纤维素酶Celluclast 1.5 L在酵母菌原生质体制备及再生中的应用

比较了在不同的酶浓度、处理时间、渗透剂和pH值下纤维素酶Celluclast 1.5 L和蜗牛酶在酵母菌原生质体的形成和再生中的应用.在最佳条件下,单独使用纤维素酶的原生质体的形成率可达60%左右,原生质体的再生率可达10%以上,与蜗牛酶类似.     

嗜杀苹果酒酵母的构建

采用核融合缺陷原生质体融合技术 ,将嗜杀质粒供体菌 5 0 45 (α ,his4,kar1— 1[KIL—K1 ]rho+ )中的嗜杀质粒转移到受体菌苹果酒酵母AW中去。用 3 5 %PEG ,3 0℃诱导融合 2 0min ,经嗜杀活性检出、小型酿造实验、遗传稳定性实验、细胞大小及体积的测定、dsRNA质粒的提取及琼脂糖凝胶电泳等实验 ,筛选出 4株遗传性状稳定、具有嗜杀活性且发酵性能良好的融合子F12、F3 0、F5 7、F65。     

啤酒酵母原生质体融合株GR8的中试研究

啤酒酵母原生质体融合株GR8的中试表明:融合株GR8凝絮性较强(本斯值为3.0);以12oBx麦芽汁为培养基,用500L发酵罐在12℃下发酵15d,发酵度为69.6%;发酵液中的双乙酰、乙醛、总高级醇、乙酸乙酯和乙酸异戊酯的含量分别为0.0390mg/L,3.26mg/L,84.7mg/L,11.14mg/L和0.99mg/L。     

跨界融合选育高效脱硫催化剂

为了有效脱除石油及其产品中的有机硫，本实验采用混合有机硫化合物为限制性底物的驯化方式，从被原油污染土壤中驯化、筛选，分离得到对有机硫具有一定脱除效果的菌株，鉴定为枯草芽孢杆菌亚种（Bacillus subtilis subsp.）；以该菌株和白腐真菌作为出发菌株，通过原生质体融合获得了遗传稳定，可产生孢子，能有效脱硫的融合子。成品油的脱硫实验可知：融合子直接应用于油品的脱硫，有较高的脱硫率和较大范围的环境耐受力，具有一定的实际应用价值。     

黑曲霉原生质体诱变及其产纤维素酶条件研究

采用紫外、硫酸二乙酯及复合诱变3种方法对黑曲霉原生质体进行诱变育种,以提高其酶活。结果表明,采用复合诱变效果最好,复合诱变所得菌株的酶活比出发菌株大幅度提高;应用单因素实验优化突变菌株的产酶条件,其最佳产酶条件培养基为:5%蔗糖、1.4%蛋白胨、0.2%磷酸二氢钾、0.05%硫酸镁,在250 mL摇瓶中装液60 mL,10%接种量、29℃下200 r/min培养96 h,酶活达到最大。     

酿酒酵母与粟酒裂殖酵母融合子检出方法的研究

为了快速检出酿酒酵母与粟酒裂殖酵母的融合子,在双亲原生质体融合处理后,利用两亲本再生营养条件的差异及氧化邻苯二胺能力的不同,通过设计选择性底层培养基和鉴定性上层培养基,进行了融合子检出方法的研究,并确定了3株融合子。该方法简单易行,可用于酿酒酵母与粟酒裂殖酵母原生质体融合育种的研究。     

米曲霉菌种选育中原生质体制备方法的研究

米曲霉(Aspergillus oryzae)是一种好气性真菌,在生长过程中可以产生多种酶,广泛的应用于食品发酵工业中。因此,米曲霉优良菌株的选育有着重要意义和实用价值。围绕原生质体制备的方法,重点阐述了菌丝和孢子制备原生质体的优缺点以及破壁酶的选择,为米曲霉菌种选育提供理论支持和技术帮助。