Antifungal activity of Streptomyces fradiae JT13 isolated from rhizosphere of Gloriosa superba Linn.

Abstract

Rhizosphere is the intense zone of microbial diversity and activities. The associated microflora of rhizosphere is found to exhibit strong antagonistic activities against phytopathogens which can cause enormous loss to crop plants. A bacterial strain was isolated from the rhizosphere of Gloriosa superba Linn., commonly known as glory lily or ‘agnisikha’ a potent medicinal plant belonging to the family Colchicaceae. The strain showed antifungal activity toward a number of fungal plant pathogens as tested in vitro . The bacterial strain was characterized through biochemical tests and identified as Streptomyces fradiae (NCBI accession no. MG679514) by16s rRNA gene sequence analysis and molecular phylogeny. The bacterial strain produces broad spectrum antifungal metabolite as it inhibited the growth of eight fungal pathogens, tested in vitro . However, the antifungal spectrum is varying with different fungal pathogens and is maximum toward Pyricularia oryzae and Acremonium sp whereas minimum toward Penicillium sp and followed by Fusarium oxysporum. The antifungal metabolite of S. fradiae JT 13 was extracted in ethyl acetate and examined in FT-IR and Uv-Vis spectroscopy. FT-IR spectrum of the metabolite suggested the presence of hydroxyl groups, hydrocarbon chassis and also indicated a double bond in the compound. Uv-vis spectrum exhibited characteristic peaks between 200-400 nm also suggested a high polyenic nature of the compound.