Aims: In general, DNA extraction from the gram-positive bacteria is too hard and expensive. The aim of this study was to utilize Polyethylene Glycol 200 in order to extract DNA from Lactobacillus acidophilus gram-positive bacteria and Pseudomonas aeruginosa gram-negative bacteria, as well as PCR conducting on them to search Lacto and ExoA genes, respectively.

Materials & Methods: Standard strains of Lactobacillus acidophilus gram-positive bacteria and Pseudomonas aeruginosa gram-negative bacteria were cultured on MRS and Mueller-Hinton agar, respectively. Then, the bacteria colony was dissolved in TE buffer and DNA was extracted using PEG 200. PCR reactions were done on the specific Lacto and ExoA genes of each organism.  

Findings: PCR was done on the selected genes for each organism; and bp231 Lacto genes were detected for the standard strain of Lactobacillus acidophilus and the strain of Lactobacillus acidophilus separated from the dairy. In addition, bp396 ExoA genes were detected for the standard strain of Pseudomonas aeruginosa and the clinical strains of Pseudomonas aeruginosa on agarose gel.

Conclusion: Since DNA extraction from gram-positive bacteria is too hard due their very strong walls, PEG 200 might be a very proper, affordable, quick, and available method to extract DNA from the gram-positive bacteria. In addition, DNA of gram-negative bacteria and fungi can simply be extracted through the method.