Intracellular morphological changes in Staphylococcus aureus induced by treatment with sodium hypochlorite

AbstractSodium hypochlorite (NaOCl) is commonly used as a disinfectant; however, its bactericidal mechanism has not yet been clarified. In the present study, the bactericidal mechanism of NaOCl was examined using microscopy and gel electrophoresis techniques withStaphylococcus aureus strain 209P.S. aureus cells treated with 500 and 1000  ppm NaOCl for 5 and 15 min were observed by SEM and TEM. SEM images of the bacterial cells treated with NaOCl showed an irregular surface, with cells being partially invaginated. TEM images of the bacterial cells showed cytoplasmic alterations, accompanied by a partially irregular cellular surfac e. Under a fluorescence microscope, we clearly observed fluorescence quenching in the 1000 ppm NaOCl-treated cells. Based on these observations, which indicated that NaOCl damaged chromosomal DNA, we next extracted chromosomal DNA from bacterial cells treated with NaOCl and performed agarose gel el ectrophoresis. Chromosomal DNA was absent in the DNA sample from the bacterial cells treated with 500 ppm NaOCl. From these biochemical results, it was strongly suggested that NaOCl degrades the chromosomal DNA ofS. aureus. We consider that the morphological changes in the cytoplasm induced by NaOCl may be related to NaOCl-induced degradation ofS. aureus chromosomal DNA.
Source: Medical Molecular Morphology - Category: Molecular Biology Source Type: research