Department of Microbiology, ELTE Eötvös Loránd University, Pázmány Péter stny. 1/C, Budapest, 1117, Hungary.
Centre for Ecological Research, Balaton Limnological Institute, Klebelsberg Kunó u. 3, Tihany, 8237, Hungary.
Sci Rep. 2020 Nov 16;10(1):19871. doi: 10.1038/s41598-020-76822-8.
Astatic soda pans of the Pannonian Steppe are unique environments with respect to their multiple extreme physical and chemical characteristics (high daily water temperature fluctuation, high turbidity, alkaline pH, salinity, polyhumic organic carbon concentration, hypertrophic state and special ionic composition). However, little is known about the seasonal dynamics of the bacterial communities inhabiting these lakes and the role of environmental factors that have the main impact on their structure. Therefore, two soda pans were sampled monthly between April 2013 and July 2014 to reveal changes in the planktonic community. By late spring in both years, a sudden shift in the community structure was observed, the previous algae-associated bacterial communities had collapsed, resulting the highest ratio of Actinobacteria within the bacterioplankton (89%, with the dominance of acIII-A1 lineage) ever reported in the literature. Before these peaks, an extremely high abundance (> 10,000 individuum l) of microcrustaceans (Moina brachiata and Arctodiaptomus spinosus) was observed. OTU-based statistical approaches showed that in addition to algal blooms and water-level fluctuations, zooplankton densities had the strongest effect on the composition of bacterial communities. In these extreme environments, this implies a surprisingly strong, community-shaping top-down role of microcrustacean grazers.
就其多种极端物理和化学特性（日水温波动大、高浑浊度、碱性 pH 值、盐度、多腐殖质有机碳浓度、富营养化状态和特殊离子组成）而言，潘诺尼亚干盐湖盆是独特的环境。然而，对于栖息在这些湖泊中的细菌群落的季节性动态及其对结构有主要影响的环境因素的了解甚少。因此，于 2013 年 4 月至 2014 年 7 月间每月对两个苏打盆进行采样，以揭示浮游生物群落的变化。在这两年的晚春，观察到群落结构的突然转变，先前与藻类相关的细菌群落已经崩溃，导致浮游细菌中放线菌的比例达到文献中报道的最高值（89%，以 acIII-A1 谱系为主）。在这些峰值之前，观察到甲壳类动物（短尾秀体溞和刺胸镖水蚤）的极高丰度（>10,000 个个体 l）。基于 OTU 的统计方法表明，除了藻类大量繁殖和水位波动外，浮游动物密度对细菌群落的组成有最强的影响。在这些极端环境中，这意味着甲壳类动物食草动物对群落结构具有令人惊讶的强大、自上而下的作用。
