Selective recovery of microalgae from diverse habitats using "phyto-specific" 16S rDNA primers

Environmental PCR is a common tool for surveying aquatic microalgae; however, universal primers generally employed are not specific to phytoplankton and typically recover nonphotosynthetic bacteria at high frequencies. Using a 16S rDNA "phyto-specific" primer, we were able to selectively amplify sequences of photosynthetic species from several mixed aquatic samples, even when large numbers of nonphotosynthetic microorganisms were present. We identified 21 microalgal sequences from three different habitats: salt marshes in Virginia, river basins in North Carolina, and sea ice in Alaska. In contrast, universal 16S primers recovered a majority of nonphotosynthetic organisms from some of the same samples. Our results indicate that phytoplankton-specific primers are efficient in selectively amplifying a broad diversity of microalgae in mixed environmental samples and, therefore, can reduce the noise from extraneous species that often dominates molecular surveys of aquatic samples.