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

Background and objective: 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 suggest more practical, faster, and less costly methodologies. Methods: Bacterial species used were Escherichia coli, provided by Dr. Leão Sampaio University Center. The evaluated/adapted methodologies were: sodium dodecyl sulfate (SDS); salting-out; Promega kit and cetyltrimethylammonium bromide (CTAB), and phenol/chloroform. Extracted DNA was examined by the agarose gel electrophoresis. Results: The SDS method revealed the best result in extracting DNA from E. coli. Its advantages include rapidness, low cost, and good concentration of the extracted material. Others 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 is better than others with better DNA quality, low cost, and good efficiency.