N2 fixation (nitrogenase activity), primary production, and diazotrophic community composition of stromatolite mats from Highborne Cay, Exuma, Bahamas, were examined over a 2-year period (1997-1998). The purpose of the study was to characterize the ecophysiology of N2 fixation in modern marine stromatolites. Microbial mats are an integral surface component of these stromatolites and are hypothesized to have a major role in stromatolite formation and growth. The stromatolite mats contained active photosynthetic and diazotrophic assemblages that exhibited temporal separation of nitrogenase activity (NA) and photosynthesis. Maximal NA was detected at night. Seasonal differences in NA and net O2 production were observed. Photosynthetic activity and the availability of reduced organic carbon appear to be the key determinants of NA. Additions of the de novo protein synthesis inhibitor chloramphenicol did not inhibit NA in March 1998, but greatly inhibited NA in August 1998. Partial sequence analysis of the nifH gene indicates that a broad diversity of diazotrophs may be responsible for NA in the stromatolites.
Similar content being viewed by others
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Steppe, T., Pinckney, J., Dyble, J. et al. Diazotrophy in Modern Marine Bahamian Stromatolites. Microb Ecol 41, 36–44 (2001). https://doi.org/10.1007/s002480000066
Received:
Issue Date:
DOI: https://doi.org/10.1007/s002480000066