从南极地区乔治王岛分离出的酵母的多样性和细胞外酶活性。
Diversity and extracellular enzymatic activities of yeasts isolated from King George Island, the sub-Antarctic region.
机构信息
Laboratorio de Genética, Depto, de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425 Casilla, Santiago 653, Chile.
出版信息
BMC Microbiol. 2012 Nov 6;12:251. doi: 10.1186/1471-2180-12-251.
BACKGROUND
Antarctica has been successfully colonized by microorganisms despite presenting adverse conditions for life such as low temperatures, high solar radiation, low nutrient availability and dryness. Although these "cold-loving" microorganisms are recognized as primarily responsible for nutrient and organic matter recycling/mineralization, the yeasts, in particular, remain poorly characterized and understood. The aim of this work was to study the yeast microbiota in soil and water samples collected on King George Island.
RESULTS
A high number of yeast isolates was obtained from 34 soil and 14 water samples. Molecular analyses based on rDNA sequences revealed 22 yeast species belonging to 12 genera, with Mrakia and Cryptococcus genera containing the highest species diversity. The species Sporidiobolus salmonicolor was by far the most ubiquitous, being identified in 24 isolates from 13 different samples. Most of the yeasts were psychrotolerant and ranged widely in their ability to assimilate carbon sources (consuming from 1 to 27 of the 29 carbon sources tested). All species displayed at least 1 of the 8 extracellular enzyme activities tested. Lipase, amylase and esterase activity dominated, while chitinase and xylanase were less common. Two yeasts identified as Leuconeurospora sp. and Dioszegia fristingensis displayed 6 enzyme activities.
CONCLUSIONS
A high diversity of yeasts was isolated in this work including undescribed species and species not previously isolated from the Antarctic region, including Wickerhamomyces anomalus, which has not been isolated from cold regions in general. The diversity of extracellular enzyme activities, and hence the variety of compounds that the yeasts may degrade or transform, suggests an important nutrient recycling role of microorganisms in this region. These yeasts are of potential use in industrial applications requiring high enzyme activities at low temperatures.
背景
尽管南极洲的环境条件对生命不利，如低温、高太阳辐射、养分可用性低和干燥，但微生物已成功在此殖民。尽管这些“嗜冷”微生物被认为主要负责养分和有机物的再循环/矿化，但酵母，特别是，仍然特征和理解不足。本研究旨在研究从乔治王岛土壤和水样中采集的酵母微生物群。
结果
从 34 个土壤和 14 个水样中获得了大量的酵母分离物。基于 rDNA 序列的分子分析显示，有 22 种酵母物种属于 12 个属，其中 Mrakia 和 Cryptococcus 属的物种多样性最高。种 Sporidiobolus salmonicolor 是迄今为止最普遍的，在 13 个不同样本的 24 个分离物中被鉴定出来。大多数酵母为耐冷，广泛地同化碳源（消耗了 29 种碳源中的 1 到 27 种）。所有物种均表现出至少 8 种胞外酶活性中的 1 种。脂肪酶、淀粉酶和酯酶活性占主导地位，而几丁质酶和木聚糖酶则较少见。两种鉴定为 Leuconeurospora sp. 和 Dioszegia fristingensis 的酵母具有 6 种酶活性。
结论
本研究中分离出了高度多样化的酵母，包括未描述的物种和以前从未从南极地区分离出的物种，包括 Wickerhamomyces anomalus，它一般不被分离于冷区。胞外酶活性的多样性，以及酵母可能降解或转化的化合物的多样性，表明微生物在该地区具有重要的养分再循环作用。这些酵母在需要在低温下具有高酶活性的工业应用中具有潜在用途。
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