## 3 Results and Discussion
### Protease and Cellulase Activity and Total Protein Content
As these compounds are liberated from rice husks during fermentation with _Trichoderma_, they can affect the estimation of total protein. Therefore, the average value between the two methods was taken into consideration. Irradiation induced a decrease in the total protein from 403 ug/mL in the control to 335 ug/mL (17% decrease) for 60 s irradiation to 260 ug/mL (35.5% decrease) for 300 s irradiation. At the end of the experiment, we evaluated the differences between the specific protease and cellulase activities, as expressed per mg of protein (Figure 3). In the case of protease activity, the behavior was similar to total protease activity, but with slightly higher specific activity than the control at 60 s irradiation (Figure 3a). This difference was marginally statistically significant. The data (Figures 2a and 3a) indicate that, although the total protein decreased by 17%, the proportion of proteases from the total protein stayed at the same level as in the control. The percent of proteases decreased significantly after 300 s compared with the control. The significant decrease of the total protein also included a decrease in protease expression. The proportion of active cellulase from the total protein in the cultures became higher at 60 s irradiation and 300 s irradiation compared to the control (Figures 2b and 3b). The decrease in the total protein resulted in higher specific cellulase activity in the irradiated samples than in the control. The previously reported data proved to be intriguing. Light has previously been shown to stimulate the transcription of cellulase in _T. reesei_[6; 41]. A more recent study found significant differences between the natural isolate of _T. reesei_ QM6 and the derivative strain QM9414, which has improved cellulase gene expression, the latter being more light-tolerant than the former [25]. The investigation showed that, although light induced an increase of transcript levels of specific cellulase genes (in agreement with other studies) of  
Figure 3: Specific protease (**a**) and cellulase (**b**) activity of _T. atroviride_ as a function of irradiation time with the 400 nm laser. The columns with the same letter do not differ significantly. Bars are \(\pm\) error bars, \(\alpha=0.05\), \(n=3\). QM9414, the actual cellulase biosynthesis and CMC-ase activity was inhibited [25]. The authors proposed the involvement of post-transcriptional regulation, but this remains to be confirmed. Even more intriguingly, in the case of QM6 even the transcript level was significantly inhibited by light, which contradicts all other previously reported observations. The effects were optical intensity-dependent, with higher optical intensity having higher effect (in the range 700-5000 lux). It is not clear if there is a correlation between the capacity of enzyme production and light tolerance. Light apparently upregulated protease secretion and activity [25]. Our data indicate that the effects of blue laser light on enzymatic activities are highly complex in _T. atroviride_ as well, but our irradiation system seems to induce a less drastic negative effect than that reported for the CMC-ase activity of _T. reesei_ QM6a and QM9414 where the activity was almost completely abolished. In fact, we even observe positive effects at later time and after three irradiations, showing only an apparent delay in reaching maximum cellulase activity upon irradiation. Until the 12 th day, and after two irradiations, the cellulase activity stayed at the basal level reached in the control after 5 days of incubation. The effects on enzymatic activities can range from inhibition to stimulation and vice versa, depending on the incubation and irradiation times. Because of the complexity of the context and the differences between the irradiation systems used, and also differences between incubation periods, a direct comparison between our data and previously reported results is difficult to make.