Growth and Some Enzymatic Responses of E. coli to Photocatalytic TiO2

Abstract

The effects of photocatalytic nano-TiO2 on the survival or die-off of E coli (e.g. TB1) were investigated under ambient conditions. Experimentally, 18-h E. coli culture was exposed to photocatalytic nano-TiO2 at various concentrations, e.g., 0 to 1,000 mg/L and particle sizes, e.g., 3 to 55 nm both in darkness and the presence of several light sources including a simulated solar light. Preliminary results indicated that there was bacteria die-off in the presence of nanoscale TiO2 in dark. Generally it appears that the growth rate decreases as the particle size decreases. The presence of light irradiation significantly enhanced the killing of E. coli due to additional photocatalytic activity. Upon exposure of E. coli to nano-TiO2 the photocatalytic activity that was generated has markedly increased the production of MDA, TTC and GST. SEM observations vividly indicate cell wall damages.