ABSTRACT: In aquatic ecosystems, the biomass, activity and composition of microorganisms are determined to a large extent by local and regional environmental conditions. While karst aquifers are an important source for drinking water, the ecology of microbial communities in karst waters has hardly been studied. This study examined the regional variations and seasonal dynamics of microbial communities in pristine karst spring waters of Slovenia (Central Europe). Fifteen springs distributed across 5 eco-regions exhibiting a strong altitudinal gradient were sampled 4 times a year. Evaluation of the microbial communities included quantification of prokaryotic biomass via total cell counts and microbial activity estimated via measurements of electron transport system activity. The taxonomic structure of the bacterial communities was analysed by terminal restriction fragment length polymorphism fingerprinting. Biological measures were complemented by a set of physico-chemical parameters, including dissolved organic carbon, nutrients, major ions, temperature, electrical conductivity, pH, and dissolved oxygen. Bacterial community structure differed significantly with seasons and eco-regions, with the latter causing greater variation. While the overall power of the environmental variable tested was a moderate factor (15%) in explaining the variability in microbial community structure, catchment altitude was a key determinant. Prokaryotic cell density and microbial activity in spring water decreased with an increase in catchment altitude and were significantly positively correlated. For a better understanding of karst ecosystems and the ecosystem service of water purification, future investigation should address karst microbial communities at a higher phylogenetic and functional resolution.

中文翻译：

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斯洛文尼亚海拔梯度上岩溶泉水中微生物丰度，活性和多样性的关键驱动力

摘要：在水生生态系统中，微生物的生物量，活性和组成在很大程度上取决于当地和区域的环境条件。虽然岩溶含水层是饮用水的重要来源，但几乎没有研究岩溶水域微生物群落的生态。这项研究检查了斯洛文尼亚（中欧）原始喀斯特泉水中微生物群落的区域变化和季节动态。每年采样4次，分布在5个生态区域中的15个弹簧呈现出很强的梯度梯度。微生物群落的评估包括通过总细胞计数对原核生物量进行定量，并通过电子传输系统活性的测量来评估微生物活性。通过末端限制性片段长度多态性指纹图谱分析了细菌群落的分类结构。一系列物理化学参数补充了生物学措施，包括溶解的有机碳，营养素，主要离子，温度，电导率，pH和溶解氧。细菌群落结构随季节和生态区域的不同而有很大差异，后者引起更大的差异。尽管所测试的环境变量的整体功效是解释微生物群落结构变异性的中等因素（15％），但集水高度是一个关键的决定因素。泉水中原核细胞密度和微生物活性随集水高度的增加而降低，并呈显着正相关。