A rapid and less instrument\|dependent protocol for direct extraction of DNA from activated sludge sample was developed. To optimize the cell lysis step, four cell lysis treatments (Freeze\|thaw, lysozyme, SDS , and thermal shock +lysozyme + SDS) were used to disrupt dispersed cells and release DNA. The efficiency of cell lysis was assessed microscopically after each treatment step. The quality and quantity of extracted DNA was determined by using both agarose gel electrophoresis and spectrophotometric meas...