Use of green light to improve the production of lignocellulose-decay enzymes by Pleurotus spp. in liquid cultivation

The influence of green light on mycelium biomass growth and extracellular enzyme activities of edible mushrooms from the Pleurotus genus, which is popularly cultivated all over the world, were investigated. The mycelium of seven strains of five species of Pleurotus (P. citrinopileatus, P. djamor, P. eryngii, P. ostreatus, and P. pulmonarius) was grown in liquid medium at 28 degrees C in the dark or under green light (515-530 nm). The light source was light-emitting diodes (LED) with photon flux density adjusted to 20 mu mol m- 2 s-1 that was kept on throughout the cultivation period. After 12 days of growth, the mycelium was recovered and used for biomass determination and the cultivation medium was used to total cellulase, endoglucanase, xylanase, and laccase activities determination. Green light reduced the mycelial biomass growth of Pleurotus spp. but increased the cellulolytic and xylanolytic activities. The cellulolytic activity of most strains increased in the presence of green light with increases ranging from 1.5 times (P. ostreatus endoglucanase) to 8 times (P. citrinopileatus total cellulase and endoglucanase). Green light reduced laccase activity for most strains with the greatest reduction for P. eryngii (2.2 times lower). The specific enzymatic activity of cellulase and endoglucanase from P. citrinopileatus, increased by 31 times and 30 times, respectively, compared to the dark. Also, the specific laccase and xylanase activities of P. pulmonarius increased 4.4 times and 6.8 times, respectively, under green light. The use of light at particular wavelengths can be a viable strategy to increase the production of enzymes for different biotechnological applications and species of Pleurotus are particularly interesting for this purpose.

Automated summary

The study found that green light can increase the cellulolytic and xylanolytic activities of Pleurotus fungi, but reduce the biomass growth of mycelium. This suggests that using light at specific wavelengths can be a viable strategy to increase enzyme production for different biotechnological applications.