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Quantifying Microbial Associations of Dissolved Organic Matter under Global Change
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  • Jianjun Wang,
  • Ang HU,
  • Mira Choi,
  • Andrew Tanentzap,
  • Jinfu Liu,
  • Kyung-Soon Jang,
  • Jay Lennon,
  • Yongqin Liu,
  • Janne Soininen,
  • Xiancai Lu,
  • Yunlin Zhang,
  • Ji Shen
Jianjun Wang
NIGLAS Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences

Corresponding Author:jjwang79@gmail.com

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Ang HU
Hunan Agricultural University
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Mira Choi
Korea Basic Science Institute
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Andrew Tanentzap
University of Cambridge
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Jinfu Liu
Nanjing Institute of Geography and Limnology, CAS
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Kyung-Soon Jang
KBSI Korea Basic Science Institute
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Jay Lennon
Indiana University
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Yongqin Liu
Tibetan Plateau Research
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Janne Soininen
University of Helsinki
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Xiancai Lu
Nanjing University
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Yunlin Zhang
Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences
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Ji Shen
NIGLAS Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences
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Abstract

Microbes play a critical role in regulating the size, composition, and turnover of dissolved organic matter (DOM), which is one of the largest pools of carbon in aquatic ecosystems. Global change may alter DOM-microbe associations with implications for biogeochemical cycles, although disentangling these complex interactions remains a major challenge. Here we develop a framework called Energy-Diversity-Trait integrative Analysis (EDTiA) to examine the associations between DOM and bacteria along temperature and nutrient gradients in a manipulative field experiment on mountainsides in contrasting subarctic and subtropical climates. In both study regions, the chemical composition of DOM correlated with bacterial communities, and was primarily controlled by nutrients and to a lesser degree by temperature. At a molecular-level, DOM-bacteria associations depended strongly on the molecular traits of DOM, with negative associations indicative of decomposition as molecules are more biolabile. Using bipartite networks, we further demonstrated that negative associations were more specialized than positive associations indicative of DOM production. Nutrient enrichment promoted specialization of positive associations, but decreased specialization of negative associations particularly at warmer temperatures in subtropical climate. These global change drivers influenced specialization of negative associations most strongly via molecular traits, while both molecular traits and bacterial diversity similarly affected positive associations. Together, our framework provides a quantitative approach to understand DOM-microbe associations and wider carbon cycling across scales under global change.