The stability and degradation of a new biological pesticide, pyoluteorin

BACKGROUND: Pyoluteorin (Plt) is a polyketide metabolite produced by fluorescent Pseudomonas. it controls a wide range of pests, including bacteria, epiphytes and weeds. It could become widely used as a new biological pesticide. However, ignorance of the stability of Plt is an obstacle to its use. This work studied the stability of Plt and its degradation under different conditions, including temperature, pH and UV-visible light irradiation. RESULTS: Degradation of Plt followed first-order reaction kinetics. The degradation rate increased with increased temperature. The derived activation energy was 11.06 J mol(-1) K-1. Plt was relatively stable in neutral solutions, in contrast to acid and alkaline solutions. Visible irradiation had no obvious effect on Plt stability, while UV irradiation greatly decreased its half-life to 3-4 days, in contrast to its half-life of 25 days in the dark. CONCLUSION: Plt is relatively stable in pure water solutions and at room temperature, with a half-life of more than 20 days. However, UV irradiation and acidic or alkaline solutions will enhance its degradation, reducing its half-life by a factor of 0.1-0.3. Before Plt is widely used as a pesticide, it might be necessary to modify the structure of Plt to make it more stable. (C) 2009 Society of Chemical Industry