Production of indole-3-acetic-acid (IAA) by the white rot fungus Pleurotus ostreatus under submerged condition of Jatropha seedcake

Abstract

The synthesis of phytohormone, indole-3-acetic acid (IAA), is not only confined to flowering plants but bacteria (especially plant growth-promoting rhizobacteria and few pathogens), yeasts, and other fungi are also known to produce this hormone and in many cases even at higher levels than plants. Three white rot fungi, Trametes versicolor, Pleurotus ostreatus, and Phanerochaete chryosporium, were examined for their ability to produce IAA when incubated with L-tryptophan. The maximum IAA production (473.55 ± 3.32 μg ml-1) was observed upon 18 d of incubation at 37°C using a medium containing 2% (w/v) Jatropha seedcake as substrate, with pH adjusted to 7.0. The IAA produced by P. ostreatus was further confirmed and characterized by thin layer chromatography and Gas Chromatograph-Turbomass Mass Spectrometer. The biological activity of IAA obtained from the culture supernatant of P. ostreatus was determined using wheat coleoptile bioassay. © 2013 Copyright Mycological Society of China.