Antimicrobial Activity and Biodegrading Enzymes of Endophytic Fungi from Eucalyptus

A total of thirty endophytic fungi were isolated from leaves and twigs of Eucalyptus globulus and Eucalyptus citriodora. Among thirty endophytic fungal isolates, four (P3MT1, P3MT2, OP4MT2 and P7ML2) are consistently producing compounds which are inhibiting Pseudomonas aeroginosa, Mycobacterium smegmatis and Candida albicans even after 10 generations tested under dual culture, well diffusion and disc diffusion methods. P3MT1 and OP4MT2 are inhibiting even a filamentous fungi Penicillium chrysogenum. The fungal isolate OP4MT2 showed highest zone of inhibition (20 mm) against Penicillium chrysogenum among two test fungi. The crude ethyl acetate extract of P3MT1 isolate showed highest zone of inhibition against Candida albicans (19 mm) by both well and disc diffusion method when compared to other fungal isolates. Another four fungal isolates (P3ML1, P6MT1, P5MT1 and P2MT1) from the same set of thirty isolates showed positive for the secretion of amylase, protease and laccase enzymes in agar plate method. Two endophytic fungal isolates (P6MT1 & P2MT1) among thirty are able to oxidize guaiacol indicating the presence of Lignin degrading enzymes. Four fungal isolates indicated presence of laccase enzymes by qualitative test were able to decolorize both methylene blue and aniline blue (synthetic dyes) in solid and liquid media. The quantitative estimation of percent decolorization of synthetic dyes by spectrophotometric method confirmed more than 90 % reduction in color is made possible by the endophytic fungi. All these fungal strains with good bioactivity are of worth studying in detail for the purification and characterization of the active compounds and enzymes. INTRODUCTION: Eucalyptus genus belonging to the family of Myrtaceae grows rapidly to a gigantic size and is one among the tallest trees of the world . There are about 500 species of Eucalyptus plants which produce essential oils . Eucalyptus oil has antibacterial, antiviral and anti fungal components and used for the treatment of cold, influenza, rhinitis, sinusitis and other respiratory infections . Almost all the plants which were studied are known to support a vast group of micro-organisms called endophytes living inside the live parts of plants . Endophytic fungi are one among these endophytes living inside the plants without causing any apparent symptoms .