Biosurfactant of Pseudomonas aeruginosa JS29 against Alternaria solani: the causal organism of early blight of tomato

Abstract

Alternaria solani (Ellis & Martin) is the causal organism of early blight of tomato (Solanum lycopersicum L.), considered to be one of the most destructive diseases in tomato. Currently, the prevention of the disease outbreak depends on the use of fungicides only. So, an investigation was carried out to study the biocontrol efficacy of the biosurfactant produced by Pseudomonas aeruginosa JS29 on early blight of tomato. In vitro studies indicated that the biosurfactant produced by this bacterial strain inhibits the growth of A. solani by 73 % at a concentration of 3.00 g l−1. In field condition 1.50 g l−1 concentration of crude biosurfactant was sufficient for complete inhibition of A. solani. The biosurfactant was characterized as rhamnolipid using Fourier transform infrared spectroscopy and liquid chromatography–mass spectrometry. This is the first report showing complete inhibition of early blight disease of tomato caused by A. solani using a rhamnolipid biosurfactant in field condition.