Comparative study of homogeneous and heterogeneous photo-oxidative treatment on bacterial cell via multianalytical techniques

• Heterogeneous photocatalyst, nano-titania is proved to be an effective antibacterial agent over the homogeneous neutral Photo-Fenton system.
• The different mode of bactericidal activity was evaluated by cultivability, viability, cell permeability, extent of inner cell components release and morphological studies.
• The heterogeneous photocatalyst causes disinfection through more of cell permeability unlike the homogeneous photocatalyst.

The present article demonstrates the comparative efficiency of homogeneous and heterogeneous photocatalyst on cell membrane destruction using electron microscopy and spectroscopy techniques to understand the mechanism and evolve an effective water disinfection technique. The antibacterial activity of a heterogeneous photocatalyst nano-TiO2 was compared with a homogeneous neutral Photo-Fenton reagent (Fe2+/3+, H2O2) against Salmonella typhimurium, a gram negative water borne bacterium. To confirm the extent of both types of photooxidation treatment on bacterial cell, production of MDA, release of RNA, DNA and protein were carefully studied and analyzed. Based on the above experimental results, heterogeneous photocatalyst shows better performance than homogeneous neutral Photo-Fenton system and the difference is attributed to the mode of disinfection in the two systems. The damage of cell membrane and release of inner cell components is higher in heterogeneous system in contrast to the neutral Photo-Fenton system which causes disinfection through both cell membrane and internal cell damage. The entrapped RNA/DNA within the cell up to 80% in Fe2+ treated bacteria substantiates destruction via internal cell damage.

Figure optionsDownload as PowerPoint slide