The measurement and distribution of dissolved nucleic acids in aquatic environments

Abstract

Nucleic acids (DNA and RNA) are ubiquitous components of the dissolved organic matter (DOM) pool of all oceanic, neritic, estuarine, and freshwater habitats studied to date. A new method for the quantitative determination of dissolved nucleic acids (DNA and RNA) in water and sediment samples was developed, evaluated, and utilized in a study of various marine and freshwater ecosystems. Under appropriate reaction conditions, dissolved DNA (D‐DNA) and dissolved RNA (D‐RNA) are efficiently removed from solution with the addition of cetyltrimethylammonium bromide (CTAB) and subsequent formation of insoluble CTA‐nucleic acid salts. The insoluble salts are collected, by filtration, onto glass‐fiber filters and analyzed for DNA and RNA with fluorometric and colorimetric procedures, respectively. The performance of this CTAB method is simple, reliable, and reproducible for measuring dissolved nucleic acids in natural aquatic environments. For the ecosystems investigated herein, D‐DNA and D‐RNA concentrations ranged from 0.56 to 88 µg liter−1 and 4.03 to 871 µg liter−1; the ratio of D‐RNA to D‐DNA ranged from 4.1 to 11.5.