A quantitative method for fungal ligninolytic enzyme screening studies

Abstract

AbstractScreening is conducted to select a fungus with desired characteristics intended for various applications, e.g. bioremediation and enzyme production. A qualitative method was used in this study for screening of fungal ligninolytic enzyme activities. The fungal ligninolytic activity was correlated with its growth from the screenings to identify a suitable fungus for solid substrate fermentation. Four strains of fungi, namely, Phanerochaete chrysosporium, Pycnoporus sanguineus, Phlebia radiata and Pleurotus sajor‐caju, were screened for their ligninolytic enzyme activities using guaiacol and remazol brilliant blue‐R (RBB‐R) as screening reagents. The screenings were conducted at both, the optimal growth temperature of each fungus and 35 °C. All the fungi, except P. radiata, showed positive guaiacol oxidation and RBB‐R decolourisation activities. On the basis of the results, P. sajor‐caju may be a suitable fungus for use in bioconversion of lignocellulose because it maintained guaiacol oxidation and RBB‐R decolourisation activities at 35 °C. Its halo‐to‐colony area ratios of guaiacol oxidation and RBB‐R decolourisation after 6 days were 7.0 and 2.7, respectively. In the subsequent growth study, the measured colony area was closely correlated with the dry fungal cell weight with a regression value (R2) of 0.971. Thus, the colony size could be used as an indicator of fungal growth if the screening media do not significantly slow the growth of fungus. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.