We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Gammaproteobacterial diazotrophs and nifH gene expression in surface waters of the South Pacific Ocean.
- Authors
Moisander, Pia H; Serros, Tracy; Paerl, Ryan W; Beinart, Roxanne A; Zehr, Jonathan P
- Abstract
In addition to the cyanobacterial N2-fixers (diazotrophs), there is a high nifH gene diversity of non-cyanobacterial groups present in marine environments, yet quantitative information about these groups is scarce. N2 fixation potential (nifH gene expression), diversity and distributions of the uncultivated diazotroph phylotype γ-24774A11, a putative gammaproteobacterium, were investigated in the western South Pacific Ocean. γ-24774A11 gene copies correlated positively with diazotrophic cyanobacteria, temperature, dissolved organic carbon and ambient O2 saturation, and negatively with depth, chlorophyll a and nutrients, suggesting that carbon supply, access to light or inhibitory effects of DIN may control γ-24774A11 abundances. Maximum nifH gene-copy abundance was 2 × 104 l−1, two orders of magnitude less than that for diazotrophic cyanobacteria, while the median γ-24774A11 abundance, 8 × 102 l−1, was greater than that for the UCYN-A cyanobacteria, suggesting a more homogeneous distribution in surface waters. The abundance of nifH transcripts by γ-24774A11 was greater during the night than during the day, and the transcripts generally ranged from 0-7%, but were up to 26% of all nifH transcripts at each station. The ubiquitous presence and low variability of γ-24774A11 abundances across tropical and subtropical oceans, combined with the consistent nifH expression reported in this study, suggest that γ-24774A11 could be one of the most important heterotrophic (or photoheterotrophic) diazotrophs and may need to be considered in future N budget estimates and models.
- Subjects
SOUTH Pacific Ocean; PROTEOBACTERIA; GENE expression in bacteria; NITROGENASE genetics; GENETIC polymorphisms; NITROGEN fixation; BACTERIAL ecology; BACTERIA
- Publication
ISME Journal: Multidisciplinary Journal of Microbial Ecology, 2014, Vol 8, Issue 10, p1962
- ISSN
1751-7362
- Publication type
Article
- DOI
10.1038/ismej.2014.49