Role of ligninolytic enzymes of white rot fungi (Pleurotus spp.) grown with azo dyes.

Background: Total three Pleurotus species (P. ostreatus, P. sapidus, P. florida) was compared for ligninolytic enzyme production grown with Coralene Golden Yellow, Coralene Navy Blue and Coralene Dark Red azo dyes in liquid medium under shaking condition.

Results: The biodegradation competency varied from species to species and it was found that P. ostreatus, P. sapidus and P. florida to 20 ppm dye concentration shows 88, 92 and 98 % decolorization, respectively for all three dyes. Production pattern of laccase, manganese dependent peroxidase and lignin peroxidase were studied during the growth of the organisms for 10 days. Laccase was found to be the major extracellular ligninolytic enzyme produced by fungus with negligible detection of lignin peroxidases. In all concentration of three dye studied, maximum laccase activity was observed on day 8, for 20 mg/l of dye laccase specific activity was 1-1.58 U/mg in P. ostreatus, 0.5-0.78 U/mg in P. sapidus and 1-1.92 U/mg in P. florida. Different factors (dye concentration, pH, protein and sugar estimation) influencing the ability of Pleurotus species to degrade dyes is documented and degradation was attributed to microbial action irrespective of pH change. HPTLC analysis of samples indicated degradation of dyes into intermediate products.

Conclusion: Level of ligninolytic enzymes is playing a major role in degradation of dye, which is dependent on time of incubation and species of fungi.