Senior Theses 2007
Brian Zielinski (2007). A microbial analysis of Bahamian ooids: defining the microbial community to identify possible calcifying bacteria.
Faculty Advisor: Joel Thompson
Ooid formation has most commonly been attributed to purely physical or chemical processes; however, theories proposing a biological origin have been gaining favor over the past decade. To aid in addressing a microbial community's ability to precipitate calcium carbonate, defining the microbial community is necessary for sound laboratory experiments, which is the goal of this research. Listed here is the phylogenetic characterization of 16S rDNA gene sequences obtained by polymerase chain reaction (FCR) amplification of mixed population DNA extracted through the calcium carbonate dissolution of ooids collected from Joulter's Cay, Bahamas. The phylogenetic analysis of 51 ooid clones by the neighbor joining method shows that the ooid sample contained diverse prokaryotes in 9 different phyla: Proteobacteria, Actinobacteria, Acidobacteria, Planctomycetes, Bacteroidetes, Cyanobacteria, Chloroflexi, Verrucomicrobia, and Spirochetes. Through analyzing all the groups' metabolic capabilities, and comparing them to the literature on biogenic carbonate formation, a list of possible calcifiers from the ooids was obtained: The Ectothiorhodospiraceae family (sulfur-oxidizing), Rhizobiales order (sulfur-oxidizing or phototrephic), Desulfobacteraceae family (sulfate reducers), Synechococcus genus and the Chloroflexi phylum (photoautotrophic or sulfur oxidizing). These results imply that the processes of phototrophy and sulfur metabolism may be intimately linked to calciuI1;l carbonate precipitation in ooids.