SUBMERGED CULTIVATION OF BASIDIOMYCETE FUNGI ASSOCIATED WITH ROOT DISEASES FOR PRODUCTION OF VALUABLE BIOACTIVE METABOLITES

Abstract

Getha K, Hatsu M, Wong HJ & Lee SS. 2009. Submerged cultivation of basidiomycete fungi associated with root diseases for production of valuable bioactive metabolites. This study is part of a screening programme aimed at searching for bioactive metabolites from basidiomycete fungi belonging to the order Polyporales. These fungi are commonly associated with root diseases in forest tree species and agricultural crops. Submerged cultivation of fungal mycelia in liquid media could reduce the time spent in obtaining antimicrobial metabolites. A total of 112 butanol extracts prepared from broth cultures of fungi belonging to several species of the genera Phellinus, Ganoderma, Rigidoporus, Tinctoporellus and Lentinus, and some unidentified polypore species, were evaluated for antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Saccharomyces cerevisiae and Rhodotorulla glutinis. Differences in antimicrobial activities observed in the different fungal genera suggested that the ability to produce bioactive compounds is not homogenously distributed among basidiomycetes. In the primary antimicrobial assay, a total of 26 (23.2%) extracts exhibited strong antimicrobial activity with percentage of inhibition concentration (%IC) ≥ 90% against one or more of the test micro-organisms. Antibacterial activity was more pronounced than antifungal activity. Ten extracts that exhibited strong antibacterial activity showed minimum inhibitory concentration (MIC) values of ≤ 0.125 μg μl^-1 against B. subtilis in a secondary assay.