毕业论文外文翻译-标准分离方法.docVIP

6.0标准分离方法 6.1富集培养 6.2用微量移液管进行单细胞分离 6.3用琼脂进行单细胞分离 6.3.1细胞在琼脂板上划线分离 6.3.2琼脂倾注平板 6.3.3雾化细胞喷淋技术 6.3.4通过琼脂划线后分离 6.4稀释技术 6.5重力分离：离心、沉淀 6.6生物趋光性分离技术 6.0标准分离方法 6.1富集培养 Enrichment cultures have long been used as a preliminary step toward single-cell isolations. They are established by adding nutrients to the natural sample, which enrich the sample so that algal growth occurs. Common enriching substances include culture medium, soil- water extract, or macronutrients (i.e., nitrate, ammonium, and phosphate), but in some cases the limiting factor is a trace metal (e.g., Boothbay Harbor, Maine, seawater in May 2003). Soil-water extract is perhaps the simplest and most successful, provided that the original soil is of good quality (Pringsheim 1912, 1950; see Chapter 2). Peat moss can be substituted for soil-water extract when enriching for desmids and some other algae from acid habitats. Organic substances, such as yeast extract (primarily for vitamins), casein (for amino acids), or urea (for nitrogen), can be added when trying to isolate osmotrophic algae, but the amount should be small, because these organic compounds almost always result in rapid bacterial growth. If bacterial growth is too high, then the enrichment culture can become anoxic or toxic, and the alga will die. For species not previously brought into culture, it sometimes pays to be inventive. Droop (1959) purchased various fruits and vegetables and added tiny amounts when trying to isolate Oxyrrhis into culture with phytoplankton for prey. He discovered that unfiltered lemon juice, and subsequently extracts from lemon rind, led to success. Ultimately, from analysis of the lemon rind, he was able to determine that the requirement was satisfied with ubiquinone or plastiquinone (Droop 1966, 1971). Conversely, this “grocery cart” approach failed when trying to isolate Dinophysis accuminata Claparède et Lachmann (Andersen, unpublished observations). 富集培养一直是作为单细胞分离的一个初步的步骤。通过在天然样品中添加丰富的营养来完成藻类的生长。常见的富集培养物包括培养基、土-水提取液，