Abstract
The effect of light illumination wavelengths on mycelial growth and synnema formation of Isaria japonica was examined using light-emitting diode (LED) with four different wavelengths: blue (wavelength: 460nm); green (520nm); yellow (592nm); and red (630nm). No significant differences were seen in the elongation rate of mycelia among the four tested groups. However, a dry weight of mycelia was significantly increased in the groups exposed to a blue or green LED as compared to the control (grown in darkness). When mycelia were grown under a yellow or red LED, no synnema formed. Blue and green LEDs were more effective in the induction of the synnema formation, and they also resulted in higher yields of synnema. However, a larger number of conidiospores formed under illumination with a blue LED. Therefore, we conclude that a green LED is optimal for both a higher yield of synnema and a suppression of conidiospore formation in commercial cultivation.
