Tundra microbial community taxa and traits predict decomposition parameters of stable, older soil organic carbon

Authors: Hale, Lauren; FENG, WENTING - Chinese Academy Of Agricultural Sciences; YIN, HUAQUN - Central South University; GUO, XUE - Tsinghua University; ZHOU, XISHU - Central South University; BRACHO, ROSVEL - University Of Florida; PEGORARO, ELAINE - University Of Florida; PENTON, C - Arizona State University; WU, LIYOU - University Of Oklahoma; COLE, JAMES - Michigan State University; KONSTANTINIDIS, KONSTANTINOS - Georgia Institute Of Technology; LUO, YIQI - University Of Oklahoma; TIEDJE, JAMES - Michigan State University; SCHUUR, EDWARD A.G. - University Of Florida; ZHOU, JIZHONG - University Of Oklahoma

Submitted to: The ISME Journal: Multidisciplinary Journal of Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2019
Publication Date: 8/5/2019
Citation: Hale, L.E., Feng, W., Yin, H., Guo, X., Zhou, X., Bracho, R., Pegoraro, E., Penton, C.R., Wu, L., Cole, J., Konstantinidis, K., Luo, Y., Tiedje, J.M., Schuur, E., Zhou, J. 2019. Tundra microbial community taxa and traits predict decomposition parameters of stable, older soil organic carbon. The ISME Journal: Multidisciplinary Journal of Microbial Ecology. 13:2901–2915. https://doi.org/10.1038/s41396-019-0485-x.
DOI: https://doi.org/10.1038/s41396-019-0485-x

Interpretive Summary: Threat of substantial greenhouse gas release from Arctic tundra soil organic carbon (SOC) exposed to warming and longer thaw durations is concerning. However, availability of tundra SOC for microbial decomposition is unclear. A 3-year lab incubation of tundra soils was used to derive SOC decomposition parameters for three SOC pools (fast, slow, and passive). Metagenomic techniques were employed to profile microbial taxa and traits involved in carbon cycling. The analyses revealed a suite of microbial classes and genes to be associated with slow and passive SOC decomposition parameters. These results portray divergent strategies by which microbial communities decompose what is considered to be stable SOC in tundra regions.

Technical Abstract: Susceptibility of soil organic carbon (SOC) in tundra to microbial decomposition under warmer climate scenarios potentially threatens a massive positive feedback to climate change, but underlying mechanisms of stable SOC decomposition remain elusive. Herein, Alaskan tundra soils from three depths (a fibric O horizon with litter and course roots, an O horizon with decomposing litter and roots, and a mineral-organic mix, laying just above the permafrost) were incubated. Resulting respiration data were assimilated into a 3-pool model to derive decomposition kinetic parameters for fast, slow, and passive SOC pools. Bacterial, archaeal, and fungal taxa and microbial functional genes were profiled throughout the 3-year incubation. Correlation analyses and a Random Forest approach revealed associations between model parameters and microbial community profiles, taxa, and traits. There were more associations between the microbial community data and the SOC decomposition parameters of slow and passive SOC pools than those of the fast SOC pool. Also, microbial community profiles were better predictors of model parameters in deeper soils, which had higher mineral contents and relatively greater quantities of old SOC than in surface soils. Overall, the analyses revealed functional potential of microbial communities to decompose tundra SOC through a suite of specialized genes and taxa. These results portray divergent strategies by which microbial communities access SOC pools across varying depths, lending mechanistic insights into the vulnerability of what is considered stable SOC in tundra regions.