A novel approach for extraction of PCR-compatible DNA from activated sludge samples collected from different biological effluent treatment plants.

This paper describes a method that facilitates the extraction of PCR-compatible DNA from different activated sludge samples. The approach involves a novel preprocessing step in DNA extraction, which removes potential PCR inhibitors. The sludge was washed with different ratios of acetone and petroleum ether after pretreatment with 0.01% Tween-20 at 50 degrees C. It was observed that an initial washing step with 50 mM Tris-HCl, pH 9.0, before the detergent-solvent step, improved the quality of the extracted DNA. The extraction protocol resulted in amplifiable amounts of DNA when 10 mg of a sludge sample was used, even in the presence of phenol as a sludge contaminant. The usefulness of the extracted template was demonstrated by carrying out different PCR reactions. The random amplified polymorphic DNA (RAPD) patterns demonstrated the diversity of sludge samples.