Saccharomyces yeasts are emerging as model organisms for ecology and evolution, and researchers need environmental Saccharomyces isolates to test ecological and evolutionary hypotheses. However, methods for isolating Saccharomyces from nature have not been standardized, and isolation methods may influence the genotypes and phenotypes of studied strains. We compared the effectiveness and potential biases of an established enrichment culturing method against a newly developed direct plating method for isolating forest floor Saccharomyces spp. In a European forest, enrichment culturing was both less successful at isolating Saccharomyces paradoxus per sample collected and less labour intensive per isolated S. paradoxus colony than direct isolation. The two methods sampled similar S. paradoxus diversity: The number of unique genotypes sampled (i.e., genotypic diversity) per S. paradoxus isolate and average growth rates of S. paradoxus isolates did not differ between the two methods, and growth rate variances (i.e., phenotypic diversity) only differed in one of three tested environments. However, enrichment culturing did detect rare Saccharomyces cerevisiae in the forest habitat and also found two S. paradoxus isolates with outlier phenotypes. Our results validate the historically common method of using enrichment culturing to isolate representative collections of environmental Saccharomyces. We recommend that researchers choose a Saccharomyces sampling method based on resources available for sampling and isolate screening. Researchers interested in discovering new Saccharomyces phenotypes or rare Saccharomyces species from natural environments may also have more success using enrichment culturing. We include step-by-step sampling protocols in the supplemental materials.

中文翻译：

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量化森林酿酒酵母采样策略的效率和偏差。

酵母菌正在成为生态学和进化的典范生物，研究人员需要分离环境中的酵母菌来测试生态学和进化论的假设。然而，从自然界中分离酿酒酵母的方法尚未标准化，分离方法可能会影响所研究菌株的基因型和表型。我们比较了现有的富集培养方法与新近开发的直接电镀分离林底酿酒酵母的直接电镀方法的有效性和潜在偏见。在欧洲的一片森林中，与直接分离相比，富集培养在每个采集的样品分离悖论酵母方面都不太成功，每个分离的S. paradoxus菌落的劳动强度都较小。这两种方法采样了相似的S. paradoxus多样性：采样的独特基因型的数量（即 在两种方法之间，每个S. paradoxus分离株的基因型多样性和S. paradoxus分离株的平均生长率没有差异，并且增长率差异（即表型多样性）仅在三种测试环境之一中有所不同。但是，富集培养确实在森林栖息地中检测到了罕见的酿酒酵母，并且还发现了两个具有异常表型的奇异链球菌。我们的结果验证了使用富集培养分离环境酿酒酵母代表性收藏的历史上通用的方法。我们建议研究人员根据可用于采样和分离筛选的资源选择酿酒酵母采样方法。感兴趣的是从自然环境中发现新的酿酒酵母表型或稀有酿酒酵母物种的研究人员，也可以通过富集培养获得更大的成功。我们在补充材料中包括分步采样协议。