Abstract
Microbial mats are often found in intertidal areas
experiencing a large range of salinities. This study investigated
the effect of changing salinities on nitrogenase activity
and on the composition of the active diazotrophic community
(nifH transcript libraries) of three types of microbial
mats situated along a littoral gradient. All three mat types
exhibited highest nitrogenase activity at salinities close to
ambient seawater or lower. The response to lower or higher
salinity was strongest in mats higher up in the littoral zone.
Changes in nitrogenase activity as the result of exposure to
different salinities were accompanied by changes in the
active diazotrophic community. The two stations higher up
in the littoral zone showed nifH expression by Cyanobacteria
(Oscillatoriales and Chroococcales) and Proteobacteria
(Gammaproteobacteria and Deltaproteobacteria). At these
stations, a decrease in the relative contribution of Cyanobacteria
to the nifH transcript libraries was observed at
increasing salinity coinciding with a decrease in nitrogenase
activity. The station at the low water mark showed low
cyanobacterial contribution to nifH transcript libraries at all
salinities but an increase in deltaproteobacterial nifH transcripts
under hypersaline conditions. In conclusion,
increased salinities caused decreased nitrogenase activity
and were accompanied by a lower proportion of cyanobacterial
nifH transcripts.
| Original language | English |
|---|---|
| Pages (from-to) | 483-491 |
| Journal | Archives of Microbiology |
| Volume | 194 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 2012 |
Keywords
- NIOO