Investigation into the physiological state of Escherichia coli K 12 cells under the action of TiO_2 nanoparticles in acidic conditions

摘要

The physiological state of E. coli K12 bacterial cells under the action of TiO_2 nanoparticles (0.04 g/L) was investigated with the method of staining by an acridine orange fluorescent dye in order to elucidate the mechanism of the antibacterial activity of nanoparticles. Experiments were performed in deionized water at initial pH 4.05-4.15, at which the surfaces of cells and nanoparticles carry opposite charges, without and with UV irradiation. The staining of the cells after incubation with TiO_2 nanoparticles showed that both in the absence and under the action of UV irradiation, inactive cells were detected only in the composition of aggregates formed in the process of incubation and predominantly in their inner part. Active cells were found mainly in the composition of small aggregates and on the surface of the large aggregates, as well as single cells. The results obtained in this study allow suggesting that the compression due to the mutual attraction of the cells coated with TiO_2 nanoparticles plays a significant role in the process of E. coli K12 cell inactivation.