Continental-scale patterns of extracellular enzyme activity in the subsoil: an overlooked reservoir of microbial activity
- Award ID(s):
- 1831952
- Publication Date:
- NSF-PAR ID:
- 10205013
- Journal Name:
- Environmental Research Letters
- Volume:
- 15
- Issue:
- 10
- Page Range or eLocation-ID:
- 1040a1
- ISSN:
- 1748-9326
- Sponsoring Org:
- National Science Foundation
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ABSTRACT At any given time, only a subset of microbial community members are active in their environment. The others are in a state of dormancy, with strongly reduced metabolic rates. It is of interest to distinguish active and inactive microbial cells and taxa to understand their functional contributions to ecosystem processes and to understand shifts in microbial activity in response to change. Of the methods used to assess microbial activity-dormancy dynamics, 16S rRNA/rRNA gene amplicons (16S ratios) and active cell staining with 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) are two of the most common, yet each method has limitations. Given that in situ activity-dormancy dynamics are proxied only by laboratory methods, further study is needed to assess the level of agreement and potential complementarity of these methods. We conducted two experiments investigating microbial activity in plant-associated soils. First, we treated corn field soil with phytohormones to simulate plant soil stress signaling, and second, we used rhizosphere soil from common bean plants exposed to drought or nutrient enrichment. Overall, the 16S ratio and CTC methods exhibited similar patterns of relative activity across treatments when treatment effects were large, and the instances in which they differed could be attributed to changes in community sizemore »