Microbial N assimilation: the forgotten process in the soil N cycle
Abstract
All microorganisms need and assimilate nitrogen (N) for growth and activity, but this part of the N cycle has largely been ignored by microbial ecologists compared to processes done by just a subset of microorganisms, such as nitrification and denitrification. Our objective was to determine if different microbial taxa display preferences for different forms of N, including ammonium (NH4+), nitrate (NO3-), and amino acids. We focused on bacteria and archaea that were present in forest soils that varied in relative N availability and used the Chip-SIP method (where RNA isotopic enrichment is measured on a phylogenetic microarray with an imaging mass spectrometer) to determine the N assimilation preferences of the most important bacterial and archaeal taxa. Short-term laboratory incubations of soil were done in the presence of 15N-labeled NH4+, NO3-, or glycine. Total RNA was extracted when assimilation peaked, hybridized to the custom probe array, and assayed for the degree of 15N labeling using nanoSIMS analysis to determine taxon-specific assimilation of the added 15N-labeled compounds. Most taxa were able to use all of the N sources, with the overall order of preference being: glycine>NH4+>>NO3-; however, the most actively assimilating taxa varied between sites and among N sources. These data demonstrate that diversity exists among microbial taxa in the universal function of N assimilation. Such diversity in N assimilation may influence interactions among members of the soil microbial community.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B11C2151M
- Keywords:
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- 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0465 Microbiology: ecology;
- physiology and genomics;
- BIOGEOSCIENCESDE: 0486 Soils/pedology;
- BIOGEOSCIENCESDE: 0497 Wetlands;
- BIOGEOSCIENCES