Morrissey Ember M, Mau Rebecca L, Schwartz Egbert, McHugh Theresa A, Dijkstra Paul, Koch Benjamin J, Marks Jane C, Hungate Bruce A
Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA.
Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV, USA.
ISME J. 2017 Aug;11(8):1890-1899. doi: 10.1038/ismej.2017.43. Epub 2017 Apr 7.
Microorganisms perform most decomposition on Earth, mediating carbon (C) loss from ecosystems, and thereby influencing climate. Yet, how variation in the identity and composition of microbial communities influences ecosystem C balance is far from clear. Using quantitative stable isotope probing of DNA, we show how individual bacterial taxa influence soil C cycling following the addition of labile C (glucose). Specifically, we show that increased decomposition of soil C in response to added glucose (positive priming) occurs as a phylogenetically diverse group of taxa, accounting for a large proportion of the bacterial community, shift toward additional soil C use for growth. Our findings suggest that many microbial taxa exhibit C use plasticity, as most taxa altered their use of glucose and soil organic matter depending upon environmental conditions. In contrast, bacteria that exhibit other responses to glucose (reduced growth or reliance on glucose for additional growth) clustered strongly by phylogeny. These results suggest that positive priming is likely the prototypical response of bacteria to sustained labile C addition, consistent with the widespread occurrence of the positive priming effect in nature.
微生物在地球上进行着大部分的分解作用，介导生态系统中的碳（C）损失，从而影响气候。然而，微生物群落的身份和组成变化如何影响生态系统碳平衡，目前还远不清楚。通过对DNA进行定量稳定同位素探测，我们展示了添加易分解碳（葡萄糖）后，单个细菌类群如何影响土壤碳循环。具体而言，我们发现，随着一组系统发育多样化的类群（占细菌群落的很大比例）转向利用更多土壤碳进行生长，添加葡萄糖后土壤碳分解增加（正激发效应）。我们的研究结果表明，许多微生物类群表现出碳利用可塑性，因为大多数类群会根据环境条件改变对葡萄糖和土壤有机质的利用。相比之下，对葡萄糖表现出其他反应（生长减少或依赖葡萄糖进行额外生长）的细菌在系统发育上聚类性很强。这些结果表明，正激发效应可能是细菌对持续添加易分解碳的典型反应，这与自然界中正激发效应的广泛存在相一致。
