The strain of Pseudomonas aeruginosa NS2001, isolated from a sample soil in Thailand, was used. The stock culture of this strain was maintained on minimum medium plates [(NH4)2SO4 1.3 g/l, KH2PO4 0.9 g/l, K2HPO4 0.6 g/l, MgSO4.7H2O 0.2 g/l, yeast extract 0.1 g/l and olive oil 10 g/l, adjusted to pH 7.0].