Spencer J F, Spencer D M, Reynolds N
Department of Life Sciences, Goldsmiths' College, London.
J Basic Microbiol. 1988;28(5):321-33. doi: 10.1002/jobm.3620280506.
In recent years, yeasts other than those belonging to the species Saccharomyces cerevisiae and Schizosaccharomyces pombe have become increasingly important in industrial processes. Species such as Pichia stipitis, Hansenula polymorpha, Zygosaccharomyces rouxii, Saccharomyces exiguus, Torulaspora delbrueckii, Yarrowia lipolytica and others whose perfect stage is known, can be manipulated genetically by classical methods, but those belonging to the genera Candida (C. utilis, C. tropicalis, C. bombicola, C. zeylanoides, C. boidinii, etc.), Brettanomyces, Cryptococcus, Rhodotorula, and others of the different form genera, cannot be treated in this way. Some, such as Schwanniomyces and Debaryomyces spp., which have a perfect stage, are still difficult to manipulate by conventional means. Genetic manipulation of these yeasts can be approached from two points of view; the first involving improvement of strains by cross-breeding within one species, and the second, the introduction of desirable genes from unrelated species and even from plants or animals. Two techniques are available for construction of industrially-useful strains from these yeasts: protoplast fusion and transformation with chimaeric plasmids containing the gene(s) it is desired to introduce into the recipient strain. The methods for the latter procedure are well known but can be laborious and time-consuming, especially if it is desired to introduce genes from plant or animal sources for production of enzymes, hormones, vaccines and similar products. Protoplast fusion is a simple technique which can be utilized in most laboratories and used for construction of improved yeast strains for brewing, baking, ethanol production and wine-making, either by the fusion of desirable strains of the same species which do not sporulate, or by introduction of genes from non-Saccharomyces species. Methods for fusion of species from different genera and isolation of the desired hybrids have been improved considerably in recent years. We have developed a method for isolation of strains carrying the desired genes by fusing a non-Saccharomyces species with an auxotrophic strain of Saccharomyces cerevisiae and selecting hybrids having the desired characteristics on appropriate media, after which the genes are transferred to the industrial strain by rare-mating, repeated protoplast fusion, or classical mating as required. The advantages and limitations of the method are under investigation.
近年来，除了酿酒酵母和粟酒裂殖酵母之外的其他酵母在工业生产过程中变得越来越重要。诸如树干毕赤酵母、多形汉逊酵母、鲁氏接合酵母、异常毕赤酵母、德巴利酵母、解脂耶氏酵母等已知其有性阶段的酵母，可以通过经典方法进行基因操作，但属于念珠菌属（产朊假丝酵母、热带假丝酵母、博伊丁假丝酵母、锡兰假丝酵母、波氏假丝酵母等）、酒香酵母属、隐球菌属、红酵母属以及其他不同形态属的酵母，则不能以这种方式处理。一些具有有性阶段的酵母，如许旺酵母属和德巴利酵母属的某些种，仍然难以通过传统方法进行操作。这些酵母的基因操作可以从两个角度入手：第一个角度是通过同一物种内的杂交育种来改良菌株，第二个角度是从无关物种甚至植物或动物中引入所需基因。有两种技术可用于从这些酵母构建具有工业用途的菌株：原生质体融合和用含有希望导入受体菌株的基因的嵌合质粒进行转化。后一种方法是众所周知的，但可能费力且耗时，特别是当希望从植物或动物来源引入基因以生产酶、激素、疫苗和类似产品时。原生质体融合是一种简单的技术，可在大多数实验室中使用，用于构建用于酿造、烘焙、乙醇生产和酿酒的改良酵母菌株，方法是将不产孢的同一物种的优良菌株进行融合，或者从非酿酒酵母物种中引入基因。近年来，不同属物种的融合方法以及所需杂种的分离方法有了很大改进。我们已经开发出一种方法，通过将非酿酒酵母物种与酿酒酵母的营养缺陷型菌株融合，并在合适的培养基上选择具有所需特性的杂种，从而分离出携带所需基因的菌株，之后根据需要通过稀有交配、重复原生质体融合或经典交配将基因转移到工业菌株中。该方法的优点和局限性正在研究中。
