通过灭活原生质体融合选育啤酒酵母新菌株

将生产用啤酒酵母(\%Saccharomyces cerevisiae)\% LQ16和QSB7分别进行单倍体化，并筛选LQ16(Ile\+-,Dat\+r)和QSB7(Ala\+-,H\-2S\+-)的遗传标记。经摇振培养后，酶解制备原生质体，对前者进行紫外灭活，而后者进行热灭活，再利用PEG进行融合，在MMR和SMMR培养基上再生，挑选融合子。连续传代稳定后鉴定融合子QSB\|XI\-6。通过细胞体积和生物量的测定，以及遗传型的分析和细胞DNA含量测定等均证实了获得的是融合子。经对啤酒感观评价，双乙酰含量测定与多种成分的气相色谱分析以及啤酒的发酵度，絮凝性、稳定性测定，并经连续多次生产试验证实QSB\|XI\-6是一株口味独特、发酵度高、絮凝性强、遗传性能稳定兼具有多种优良性状的啤酒酵母生产新菌株。

BREEDING OF YEAST FOR BEER MANUFACTURING BY INACTIVATED PROTOPLAST FUSION

QSB XI6 ,one offusants, was obtained by PEG induced fusion between UV inactivated protopolastsof Saccharomyces cerevisiae LQ16(Ile- , Datr) and heat inactivated protoplasts of S. cerevisiae QSB7(Ala- ,H2S- ) .Thecellvolume,bicmass,genotypeand DNAcontentofthefusant were measuredin comparison with ofitsparentsandtheresultsshowedthat QSB XI6 wasafusant. Thefermentation ability andtheflocculentcapacity ofthisfusant were higherthanthose ofitspar ents.The diacetylcontentofthebeerproduced bythefusant was measured andsomeothercomposi tionsofthe beer wasalso analysed by gas chromatography.The sensory evaluation ofthe beer was much better and the flavour was distinctive.the results of many production trials in successioin showedthatallgood characteristics of QSB XI6 werestable.