Responses of Aspergillus oryzae to stimuli from near-UV light irradiation in the presence or absence of titanium dioxide.

摘要

The responses of Aspergillus oryzae to the stimuli from near-UV irradiation were investigated by using a black light fluorescent lamp in the presence or absence of TiO₂ particles. Light irradiation at an intensity of 6 W/m2 strongly inhibited the growth of germinated pellets of A. oryzae. This growth inhibition was weakened by TiO₂ particles (0.05 g/l), especially in the initial growth phase, in which the expression level of catalase gene (catB) was approximately three times higher than that in the absence of TiO₂ particles. However, the initial induction of catB expression by H₂O₂ pretreatment did not restore the growth under the black light irradiation. The weakening of growth inhibition is thought to result from alternative physiological responses of A. oryzae against stimulus by photo-excited TiO₂.