Zaky Abdelrahman Saleh, Greetham Darren, Louis Edward J, Tucker Greg A, Du Chenyu
Division of Food Sciences, School of Biosciences, University of Nottingham, Nottingham LE12 5RD, UK.
School of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH, UK.
J Microbiol Biotechnol. 2016 Nov 28;26(11):1891-1907. doi: 10.4014/jmb.1605.05074.
Yeasts that are present in marine environments have evolved to survive hostile environments that are characterized by high exogenous salt content, high concentrations of inhibitory compounds, and low soluble carbon and nitrogen levels. Therefore, yeasts isolated from marine environments could have interesting characteristics for industrial applications. However, the application of marine yeast in research or industry is currently very limited owing to the lack of a suitable isolation method. Current methods for isolation suffer from fungal interference and/or low number of yeast isolates. In this paper, an efficient and non-laborious isolation method has been developed and successfully isolated large numbers of yeasts without bacterial or fungal growth. The new method includes a three-cycle enrichment step followed by an isolation step and a confirmation step. Using this method, 116 marine yeast strains were isolated from 14 marine samples collected in the UK, Egypt, and the USA. These strains were further evaluated for the utilization of fermentable sugars (glucose, xylose, mannitol, and galactose) using a phenotypic microarray assay. Seventeen strains with higher sugar utilization capacity than the reference terrestrial yeast NCYC 2592 were selected for identification by sequencing of the ITS and D1/D2 domains. These strains belonged to six species: , , , , , and . The ability of these strains for improved sugar utilization using seawater-based media was confirmed and, therefore, they could potentially be utilized in fermentations using marine biomass in seawater media, particularly for the production of bioethanol and other biochemical products.
存在于海洋环境中的酵母已经进化到能够在恶劣环境中生存，这些环境的特点是外源盐含量高、抑制性化合物浓度高以及可溶性碳和氮水平低。因此，从海洋环境中分离出的酵母可能具有有趣的工业应用特性。然而，由于缺乏合适的分离方法，海洋酵母在研究或工业中的应用目前非常有限。目前的分离方法受到真菌干扰和/或酵母分离物数量少的困扰。在本文中，开发了一种高效且不费力的分离方法，并成功分离出大量无细菌或真菌生长的酵母。新方法包括一个三轮富集步骤，随后是一个分离步骤和一个确认步骤。使用这种方法，从在英国、埃及和美国采集的14个海洋样本中分离出了116株海洋酵母菌株。使用表型微阵列分析法进一步评估了这些菌株对可发酵糖（葡萄糖、木糖、甘露醇和半乳糖）的利用情况。选择了17株糖利用能力高于参考陆生酵母NCYC 2592的菌株，通过ITS和D1/D2结构域测序进行鉴定。这些菌株属于六个物种： 、 、 、 、 和 。这些菌株在基于海水的培养基中提高糖利用的能力得到了证实，因此，它们有可能用于海水培养基中利用海洋生物质的发酵，特别是用于生产生物乙醇和其他生化产品。
