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NifH expression by five groups of phototrophs compared with nitrogenase activity in coastal microbial mats

Severin, I. and Stal, L.J. (2010) NifH expression by five groups of phototrophs compared with nitrogenase activity in coastal microbial mats. FEMS Microbiology Ecology, 73, 55-67. ISSN 0168-6496.

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Official URL: http://dx.doi.org/10.1111/j.1574-6941.2010.00875.x

Abstract

Diazotrophic (nitrogen-fixing) Cyanobacteria are often structurally dominant in coastal microbial mats but diazotrophs from other bacterial lineages are also present and active. The expression of nifH by four nonheterocystous Cyanobacteria and one member of the Gammaproteobacteria was followed over a 24-h cycle using quantitative reverse transcriptase-PCR. Daily nifH expression patterns were compared with the actual nitrogenase activity (NA) of the entire mat community. Lyngbya sp. was identified as the dominant cyanobacterium but, although recognized as a diazotroph, its cell-specific and abundance-related nifH expression was low. Unexpectedly, the other three cyanobacterial phylotypes dominated community nifH expression at all stations. Also, the gammaproteobacterium showed high levels of cell-specific nifH expression but its nifH copy number was low. Its contribution to the whole community nifH expression was therefore low. These results indicate that there were varying levels of cell-specific expression of nifH in the different mat types and more so, varying contributions to the overall nifH expression by the different diazotrophs. Furthermore, NA did not follow nifH expression patterns.

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:6456
Deposited On:01 Jul 2010 02:00
Last Modified:24 Apr 2012 16:43

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