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HERO ID
1528770
Reference Type
Journal Article
Title
Nitrate and ammonium uptake by natural stream sediment microbial communities in response to nutrient enrichment
Author(s)
Bunch, ND; Bernot, MJ
Year
2012
Is Peer Reviewed?
1
Journal
Research in Microbiology
ISSN:
0923-2508
EISSN:
1769-7123
Publisher
ELSEVIER SCIENCE BV
Location
AMSTERDAM
Volume
163
Issue
2
Page Numbers
137-141
Language
English
PMID
22155107
DOI
10.1016/j.resmic.2011.11.004
Web of Science Id
WOS:000302446200009
Abstract
Anthropogenic activities have increased nitrogen concentration in many ecosystems. Because microbes have higher metabolic rates relative to larger organisms, microbial activity may influence nitrogen movement and degradation significantly in ecosystems. Thus, the ability for microorganisms to adapt to increasing nitrogen concentrations is essential to ecosystem sustainability. We measured sediment microbial community nitrogen assimilation after sustained nitrogen enrichments using in vitro and isotopic techniques. Mixed-microbial communities were exposed to-enriched concentrations of NO(3)-N (1 mg l(-1)) and NH(4)-N (30 μg l(-1)) for four weeks. Each week, filtered water samples were collected from each mesocosm and sediment was removed to quantify rates of nitrogen assimilation by the sediment microbial community. During the fourth week, isotopic tracers (15)NO(3) and (15)NH(4) were added to mesocosms to directly measure nitrogen incorporation into microbial cells as organic (15)N. Initial microbial responses to nitrogen enrichment were distinctly different from the sustained microbial community responses. NH(4)-N uptake was initially stimulated with NH(4)-N enrichments but increased uptake rates were not sustained over time. Sustained responses to changing nitrogen availability equilibrated within 1-3 weeks (depending on nitrogen form), indicating that even though microbial communities can respond to increased availability, potential for increased assimilation is limited.
Keywords
Nitrogen; Nitrate; Ammonium; Nutrient loading; Uptake; Sediment
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