Effects of Pulsed Light on Mycelium Growth and Conidiation in Aspergillus oryzae

Understanding how Aspergillus oryzae responds to light is critical for developing efficient light regulation strategies in the brewing and waste treatment industries. Although continuous light is known to restrict A. oryzae, little is known about A. oryzae’s sensitivity to light with photoperiod. In this study, we used pulse wave modulation (PWM) to generate nine pulsed blue light (PBL) treatments with varying peak light intensities and frequencies. The effect of PBL on A. oryzae was then compared to that of continuous blue light (CBL). Our findings showed that A. oryzae GDMCC 3.31 mycelium developed faster and produced more conidia under PBL with specific peak intensities and frequencies than under CBL treatment when the light dose and average light intensity were held constant. The colony diameter and conidia count under the two PBL treatments (PL-20_40%_1 Hz and PL-400_20%_10 kHz) were 1.13 and 1.22 times greater than under the CBL treatments, respectively. This different response may be mainly attributed to A. oryzae’s adaptation to the light–dark cycles in nature. Furthermore, an interactive effect was found between peak light intensity and frequency. This work includes pulsed wave modulation as a new factor that influences the A. oryzae photoresponse and recommends it in the development of light regulation methods for fermentation.