Isolation and identification of two laccase producer fungi from bagass and sugarcane rhizosphere

Complex of enzymes in the name of Ligninase are involved in lignin degradation. Special properties of Laccase among the lignin degradation enzymes make them more important. Oxidation of wide range of substrates، high heat tolerance and acidic isoelectric pH are main properties of laccase. Identification of new microorganism with higher production and secretion laccase is very valuable. In this research، laccase producing fungi was isolated، screened and identified from bagass and sugarcane rhizosphere. In order to screen laccase producing strains malt extract agar medium containing 0. 1gl-1 ABTS or 0. 5mMl-1 Guaiacol was used. Laccase activity was determined as described by Niku-Paavola et al. In this study، among 22 fungi screened، Alternaria alternata and Retroconis sp isolates were identified with the highest laccase production. Two species were identified using PCR amplification and sequencing of the internal transcribed spacer ‘ITS’regions of the ribosomal DNA and by basic morphology. In this research laccase activity has been determined in agitation and stationary state. These results showed that agitation and stationary conditions had different effects on laccase production rate of these isolates.