Demonstration of extraction and PCR amplification of DNA from phytoplankton of lakes with high humic acid content

Lakes with high levels of dissolved organic matter are common in northern t emperate regions. These habitats are sensitive to environmental and climate change, but the molecular ecology and eco-physiology of their phytoplankto n have been under studied, in part because the DOM interferes with molecula r and biochemical analyses of these populations. We developed a procedure w hich uses polyvinylpyrrolidone to adsorb interfering material during the ex traction of nucleic acids from these populations. This procedure does not d epend on enzymatic lysis and yields DNA of sufficient quality to serve as a template for PCR amplification of specific genetic sequences. In particula r, we detected fragments of the conserved rbcL gene encoding the large subu nit of the Rubisco enzyme from the phytoplankton of lakes with high DOM. Ou r extraction procedure may be useful to other workers studying similar popu lations.