Abstract

A method was developed for the determination of dissolved DNA in pasturage soil and was based on the concentration of dissolved DNA by ethanol precipitation of 0.2 µm - pore size filtered water. The DNA concentrated extracts were quantified by the fluorescence of Hoechst 33258-DNA complexes. The fluorescence that was not attributable to DNA was corrected by DNase I digestion of the extracts and it averaged 25% of the total fluorescence for all samples. Concentration of dissolved extracellular DNA from a variety in the soil ranged from 131.26 to 29.08 DNA ng/ml in 10 gr soil. The agarose gel stained with ethidium bromide (electrophoresis technique) was used for soil dissolved DNA. The method of Hoefer TKO 100 DNA Mini-Fluorometer is simple for extracellular DNA and is more sensitive than previously described methods for the determination of extracellular DNA. The TKO 100 Mini-Fluorometer is designed specifically for the accurate quantitation of DNA in dilute samples. The unit can also be used for assaying protease, glucuronidase (GUS) and 1-galactosidase activity.

Key words:  Extracellular DNA, fluorescence, electrophoresis technique.