Effects of Blue-Light Laser Irradiation on the Enzymatic Activities and Sporulation of <i>Trichoderma atroviride</i> Grown on Rice Husks

Abstract

Light is known to impact various aspects of Trichoderma, with possible implications for industrial and agricultural applications. In this study, we investigated the irradiation of Trichoderma atroviride with blue light using a laser source system. We determined the cellulase and protease activities and the effects of UV–Vis absorption of the filtrated culture on conidia formation, dimension, and behavior, and on the apparent chlamydospore abundance, as a function of irradiation duration, dose of irradiation, and moment of irradiation. We show that the effects on the enzymatic activities range from positive to neutral to negative. Compared with previous studies, our stimulation with light does not show a drastic negative effect on the cellulase (CMC-ase) activity, but it seems to delay the maximum activity over time. The effects on the proteases are partially in agreement with the only previous study reported for the light effects on protease activity. The number of conidia is increased upon irradiation, representing an expected behavior, and we show for the first time to the best of our knowledge that the conidia dimensions and chlamydospore number also increase. Our data also suggest that the highest dose resulted in the conidia clustering around the liquid–air interface, suggesting an increased hydrophobic character.

Keywords

• <i>Trichoderma</i>
• laser light
• industrial enzymes
• cellulase
• protease
• conidia