Comparing protocols of DNA extraction from Escherichia coli: Analysis of purity and concentration by gel electrophoresis


Background and objectives: Given the difficulty in establishing an ideal method that can successfully extract bacterial deoxyribonucleic acid (DNA) in Gram-negative bacteria, the objective of this work was to compare protocols for the extraction of bacterial DNA and to report the more practical, faster, and less costly ones.Methods: Bacterial species used were Escherichia coli, provided by Dr. Leão Sampaio University Center. The methods used to extract bacterial DNA were: sodium dodecyl sulfate (SDS), salting-out, cetyltrimethylammonium bromide (CTAB)/Phenol-Chloroform, and commercial kit for DNA isolation from Promega. The extracted DNA by all the methods was detected and assessed by the agarose gel electrophoresis. Results: The best result was that obtained by the SDS method, it showed the greatest advantage for bringing speed, low cost, and good concentration of the extracted material. The other methods showed low-quality DNA, probably due to the presence of large amounts of proteins in the cell wall of E. coli interfering with the quality of the samples. Conclusions: It was concluded that the SDS method can provide better DNA in terms of quality, which is preferred for the amplification by the polymerase (PCR) chain reaction. This will be helpful for diagnostic microbiologists because of the low cost and good quality of the extracted DNA.