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Diazotrophic Anaeromyxobacter Isolates from Soils.
- Source :
-
Applied and environmental microbiology [Appl Environ Microbiol] 2020 Aug 03; Vol. 86 (16). Date of Electronic Publication: 2020 Aug 03 (Print Publication: 2020). - Publication Year :
- 2020
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Abstract
- Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based on soil DNA/RNA/protein sequencing could globally detect the nitrogenase genes/proteins of Anaeromyxobacter (in the class Deltaproteobacteria ), commonly distributed in soil environments and predominant in paddy soils; this suggests the importance of Anaeromyxobacter in nitrogen fixation in soil environments. However, direct experimental evidence is lacking; there has been no research on the genetic background and ability of Anaeromyxobacter to fix nitrogen. Therefore, we verified the diazotrophy of Anaeromyxobacter based on both genomic and culture-dependent analyses using Anaeromyxobacter sp. strains PSR-1 and Red267 isolated from soils. Based on the comparison of nif gene clusters, strains PSR-1 and Red267 as well as strains Fw109-5, K, and diazotrophic Geobacter and Pelobacter in the class Deltaproteobacteria contain the minimum set of genes for nitrogenase ( nifBHDKEN ). These results imply that Anaeromyxobacter species have the ability to fix nitrogen. In fact, Anaeromyxobacter PSR-1 and Red267 exhibited N <subscript>2</subscript> -dependent growth and acetylene reduction activity (ARA) in vitro Transcriptional activity of the nif gene was also detected when both strains were cultured with N <subscript>2</subscript> gas as a sole nitrogen source, indicating that Anaeromyxobacter can fix and assimilate N <subscript>2</subscript> gas by nitrogenase. In addition, PSR-1- or Red267-inoculated soil showed ARA activity and the growth of the inoculated strains on the basis of RNA-based analysis, demonstrating that Anaeromyxobacter can fix nitrogen in the paddy soil environment. Our study provides novel insights into the pivotal environmental function, i.e., nitrogen fixation, of Anaeromyxobacter , which is a common soil bacterium. IMPORTANCE Anaeromyxobacter is globally distributed in soil environments, especially predominant in paddy soils. Current studies based on environmental DNA/RNA analyses frequently detect gene fragments encoding nitrogenase of Anaeromyxobacter from various soil environments. Although the importance of Anaeromyxobacter as a diazotroph in nature has been suggested by culture-independent studies, there has been no solid evidence and validation from genomic and culture-based analyses that Anaeromyxobacter fixes nitrogen. This study demonstrates that Anaeromyxobacter harboring nitrogenase genes exhibits diazotrophic ability; moreover, N <subscript>2</subscript> -dependent growth was demonstrated in vitro and in the soil environment. Our findings indicate that nitrogen fixation is important for Anaeromyxobacter to survive under nitrogen-deficient environments and provide a novel insight into the environmental function of Anaeromyxobacter , which is a common bacterium in soils.<br /> (Copyright © 2020 American Society for Microbiology.)
Details
- Language :
- English
- ISSN :
- 1098-5336
- Volume :
- 86
- Issue :
- 16
- Database :
- MEDLINE
- Journal :
- Applied and environmental microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 32532868
- Full Text :
- https://doi.org/10.1128/AEM.00956-20