Degradation of eucalypt waste components by Lentinula edodes strains detected by chemical and near-infrared spectroscopy methods

There are many changes, both qualitative and quantitative, in eucalypt waste during growth and fructification of Lentinula edodes. Wet chemical analysis and near-infrared (NIR) spectroscopy were used in conjunction with multivariate regression and principal components analysis to monitor biodegradation of eucalyptus waste during growth of several L. edodes strains. Weight and component losses of eucalypt residue after biodegradation by L. edodes strains were compared for periods of 1 to 5 mo. Decrease in cellulose, hemicellulose, and lignin contents occurred, however it was not concomitant. Measurement of lignin degradation by NIR and wet chemical analysis indicated its attack in the early stages of biodegradation. Selective lignin degradation by L. edodes was observed up to 2 mo of biodegradation for strains DEBIQ and FEB-14. One group of degraded substrate was identified based on the principal component analysis (PCA) of the data on their biodegradation time. Samples treated for 5 months by L. edodes strains (DEBIQ, UFV or FEB-14) differed from other, but no discrimination was observed among them. By the end of 5 mo, NIR analyses showed decrease of about 18-47% cellulose, 35-47% polyose and 39-60% lignin. These data were used for comparison with those obtained by wet chemical method for the degradation of the substrate by other five L. edodes strains cultivated at the same conditons. NIR calibration developed in this study was proven to be perfectly suitable as an analytical method to predict the changes in lignocellulose composition during biodegradation.