Abstract
Background: All microorganisms are negatively charged using the sulfate groups in acid mucopolysaccharids , ionized phosphate groups of the phospholipids and some other chemical groups on the their surfaces. Recent researches concerning the effect of electrical fields on the biologic processes, anti-inflammatory and carcinogenic effects provides a good opportunity to investigate whether these fields can gravitate or repel the microorganisms or not, therefore in this experimental study electrical gravitation of Staphylococcus aureus in liquid culture medium was investigated.
Methods: To make the electrical field a plastic tank with positive electrode (cathode) and negative electrode (anode) was constructed on the either sides. Afterwards the tank was filled with sterile nutrient broth medium and S. aureus ATCC 29213 was cultured. For homogenization of the bacteria in all parts of the medium, the medium was stirred and positive and negative charges were generated in the poles of the tank. After 24 hours, sampling was performed from different parts of the tank and the samples were cultured in nutrient agar medium. This experiment repeated three times in the same manner and the average results were calculated.
Results: Average results of bacterial counts on samples taken from different parts of the tank with an electrical field intensity of 20 Nm/colon in all three experiments showed that the numbers of S. aureus near the positive electrode was 8.2×103 CFU/ml, in the middle of the medium was 6.2×103 CFU/ml and near the negative electrode was 3.6×103 CFU/ml .
Conclusion: The electrical fields caused S. aureus gravitation towards positive electrode.