Isolation and characterization of a lipopeptide bioemulsifier produced by Pseudomonas nitroreducens TSB.MJ10 isolated from a mangrove ecosystem

Abstract

Pseudomonas nitroreducens TSB.MJ10 exhibiting growth and bioemulsifier production with 0.5 percent sodium benzoate as the sole carbon source was isolated from a mangrove ecosystem in the vicinity of a petroleum pump. The bioemulsifier is a lipopeptide that is stable over a pH range of 5-11 and a temperature range of 20-90 degrees C and showed emulsifying activity in the presence of relatively high NaCl concentrations (up to 25 percent). The bioemulsifier formed stable emulsions with aliphatic (hexadecane, n-heptane, cyclohexane), aromatic (xylene, benzene, toluene) and petroleum (gasoline, diesel, kerosene, crude oil) compounds. It exhibited a maximum emulsification activity with weathered crude oil (97 percent) and was capable of transforming the rheological behavior of the pseudoplastic to a Newtonian fluid. The results reveal the potential of the bioemulsifier for use in bioremediation of hydrocarbons in marine environments and in enhanced oil recovery.