Morphological and phylogenetic identification of a hyper laccase producing strain of Schizophyllum commune NI-07 exhibiting delignification potential

Abstract

In nature lignin degrading enzymes of white rot fungi (WRF) degrade lignin, amongst which laccase plays an important role. Our objective was to screen for laccase secreting indigenous WRF. Culture-dependant and molecular methods were used in combination for identification and characterization. NI-07, the most potent laccase producing isolate was identified as Schizophyllum commune, strain (MTCC- 11893). It had pinkish grey split gills, radiating from the attachment point and cylindrical to ellipsoidal smooth white spores. The generative hyphae were thin-walled, having septa and clamp connections, skeletal hyphae were swollen centrally and broad and binding hyphae were comparatively thick-walled and branched. The ITS/ 5.8S rRNA gene sequence as per phylogenetic tree results showed best matching with Agaricaceae sp. 647 (Sequence ID: gb|JQ312209.1|) as per cladogram while the phylogram showed significant variation and is deposited with GenBank (Bank It 1679236 Schizophyllum KF911323). Production of lignolytic enzymes by S.commune was investigated in liquid medium under conditions of vegetative growth as well as solid state fermentation in comparison to the reference culture Trametes versicolor . Laccase was the sole enzyme detected in S. commune with highest activities of 737.78±42.1UmL-1 being obtained in submerged fermentation on day 7 and 338.62±42.5U mL-1 in SSF on day 5 and was considerably higher in comparison to T.versicolor. A preliminary investigation conducted to assess the efficacy of this WRF in delignification confirmed its competence in enhancing digestibility of straw by 10- 14%.