Elucidation of microbial communities from South Florida beaches using 16S rRNA sequence analysis

The composition of marine bacterial communities from South Florida beaches were characterized using 16S rRNA sequence analysis. To compare cultivable and non-cultured populations, community genomic DNA was extracted directly from sand and seawater samples and from two cultured equivalents. Only two of the 86 (2.3%) direct extracted sequences and 79 of 150 (52.6%) culture sequences belong to known isolates in Ribosomal Database (version 9.0) at 95% confidence level. At low stringency (p=0.70), the populations cluster into several unknown clads with early divergence, indicating the presence of novel well established bacterial groups. Members of phylum Bacteroidetes, Firmicuites and Proteobacteria were identified, with the latter being the most prevalent in culture. Diversity indices rank Hollywood beach > Fort Lauderdale > Hobie beach. Taxonomic representation indicates marine water as more diverse compared to dry sand and wet sand. A combination of phylogenetic markers will be needed to define the immense diversity of this niche.