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Genetic characterization of the nitrate reducing community based on narG nucleotide sequence analysis
D Chèneby1, S Hallet, M Mondon
1UMR A111 Microbiologie des Sols, Géosols, Institut National de la Recherche Agronomique, 17, rue Sully, B.P. 86510, 21065 Dijon Cedex, France. philippo@dijon.inra.fr
Microbial Ecology
|May 10, 2003
Summary
This study reveals a more complex soil nitrate-reducing bacterial community than previously known. Maize rhizospheres specifically select for certain nitrate-reducing bacteria, altering community structure.
Area of Science:
- Microbiology
- Environmental Science
- Soil Science
Background:
- Facultative anaerobes utilize membrane-bound nitrate reductase (encoded by narGHJI operon) for nitrate respiration.
- Nitrate reduction is a key step in denitrification, crucial for global nitrogen cycling in soils.
Purpose of the Study:
- To investigate the diversity of nitrate-reducing bacteria in soil and maize rhizosphere.
- To analyze the structure and shifts in the functional community of nitrate-reducing bacteria.
Main Methods:
- Direct PCR, cloning, and sequencing of narG gene fragments.
- Phylogenetic analysis of 128 narG sequences.
- Restriction fragment length polymorphism (RFLP) analysis.
Main Results:
- Identified two main groups of nitrate-reducing bacteria: Gram-positive and Gram-negative.
- Discovered novel narG lineages within Gram-negative bacteria.
- Observed a significant shift in the rhizosphere, with higher abundance of dominant groups and lower diversity.
Conclusions:
- The soil nitrate-reducing bacterial community is more complex than previously understood.
- Maize rhizospheres exert selective pressure, favoring specific bacterial groups.
- RFLP analysis is effective for studying the diversity and structure of nitrate-reducing communities.