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The structure of the microbial community and the diversity of the functional gene for dinitrogenase reductase and its transcripts were investigated by analyzing >1400 16S rRNA gene and nifH sequences from two microbial mats situated in the intertidal zone of the Dutch barrier island Schiermonnikoog. Although both microbial mat communities were dominated by(More)
The filamentous, non-heterocystous cyanobacterium Microcoleus chthonoplastes is a cosmopolitan organism, known to build microbial mats in a variety of different environments. Although most of these cyanobacterial mats are known for their capacity to fix dinitrogen, M. chthonoplastes has not been assigned as a diazotrophic organism. None of the strains that(More)
All cyanobacterial mats that have been investigated have been proven to be diazotrophic, i.e., use atmospheric dinitrogen (N(2)) as the source of nitrogen. Many cyanobacteria possess the capacity to fix N(2) and different species have evolved various ways to cope with the sensitivity of nitrogenase toward oxygen which is produced by these oxygenic(More)
The fixation of nitrogen in cyanobacterial mats situated along the littoral gradient on a Dutch barrier island was investigated by using a high-resolution online, near-real-time acetylene reduction assay. Light-response curves of nitrogenase activity yielded a variety of physiological parameters that changed during a day-night cycle. The fitted parameters(More)
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(More)
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.(More)
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