Recovery and phylogenetic analysis of nifH sequences from diazotrophic bacteria associated with dead aboveground biomass of Spartina alterniflora

DNA was extracted from dry standing dead Spartina alterniflora stalks as we ll as dry Spartina wrack from the North Inlet (South Carolina) and Sapelo I sland (Georgia) salt marshes. Partial nifH sequences were PCR amplified, th e products were separated by denaturing gradient gel electrophoresis (DGGE) , and the prominent DGGE bands were sequenced. Most sequences (109 of 121) clustered with those from alpha -Proteobacteria, and 4 were very similar (> 99%) to that of Azospirillum brasilense. Seven sequences clustered with th ose from known gamma -Proteobacteria and five with those from known anaerob ic diazotrophs. The diazotroph assemblages associated with dead Spartina bi omass in these two salt marshes were very similar, and relatively few major lineages were represented.