Objective:To compare the different DNA extraction methods and establish an efficient and sensitive method of DNA extraction from bacteria for PCR and Real-time PCR.Methods:Bacillus coli DNA with the same concentration was extracted by 5 different DNA extraction methods

the Proteinase K method

the alkali-lysis method

the Chelex-100 with NP40 or Triton X-100 and the water-boiling method to determine OD260/280.Bacillus coli DNA with different concentrations wewe extracted to be amplified by PCR and Real-time PCR for compariing the sensitivity.Results:Among these extraction methods

Chelex-100 + NP40 method was with the best purity and sensitivity and offered a higher OD260/280(1.79±0.03).Neither false positive nor false negative was found in PCR and Real-time PCR

The sensitivity was at 10/ml of bacteria concentratio.Conclusion:The DNA extraction based on Chelex-100 + NP40 is effective

specific and sensitive

and it accommodate to PCR and Real-time PCR.