Program in Ecology, Evolution, and Conservation Biology, University of Illinois, Urbana, IL, USA.
FEMS Microbiol Ecol. 2013 Mar;83(3):541-51. doi: 10.1111/1574-6941.12012. Epub 2012 Oct 22.
Shifts in the composition of dissolved organic matter (DOM) may be a principal factor effecting changes in bacterial community composition. Emerald Lake, a high-elevation lake with DOM dominated by terrestrial sources in the spring with increasing phytoplankton-derived inputs throughout the ice-free season, provided a natural experiment with which to investigate the importance of resource-mediated drivers. Glycolate-utilizing bacteria, a subset of the bacterial community able to use algal exudates, were characterized using DNA analysis of glycolate oxidase subunit D (glcD) genes from Emerald Lake samples collected approximately biweekly from ice-cover (June) through fall turnover (September). glcD genes were not detected in early-season samples when the lake was ice-covered and phytoplankton-derived resources were scarce. Following this period, glcD gene composition exhibited significant changes through time, which were strongly correlated with the combination of fluorescence index, an indicator of the proportion of lake vs. terrestrially derived DOM, and dissolved inorganic nitrate + nitrite. These results suggest that seasonal shifts in DOM source and environmental variables that affect the composition of algal-derived dissolved resources drive changes in the relative abundance and composition of putative glycolate-utilizing bacteria. These findings strengthen the evidence for shifts in DOM structuring bacterial communities.
溶解有机物质 (DOM) 组成的变化可能是影响细菌群落组成变化的主要因素。翡翠湖是一个高海拔湖泊，春季 DOM 主要来源于陆地，整个无冰季节浮游植物衍生的输入不断增加，为研究资源介导的驱动因素的重要性提供了一个自然实验。利用 Emerald Lake 样本的 DNA 分析，对能利用藻类分泌物的细菌亚群——乙醛酸盐利用细菌进行了研究，这些样本是从冰盖期（6 月）到秋季翻转期（9 月）每隔两周收集一次。在湖泊被冰覆盖且浮游植物衍生资源稀缺的早期季节样本中未检测到 glcD 基因。在此期间，glcD 基因组成随时间发生显著变化，与荧光指数（指示湖泊与陆地来源 DOM 的比例）和溶解无机硝酸盐+亚硝酸盐的组合密切相关。这些结果表明，DOM 来源和影响藻类衍生溶解资源组成的环境变量的季节性变化，驱动了潜在乙醛酸盐利用细菌的相对丰度和组成的变化。这些发现加强了 DOM 结构细菌群落变化的证据。
