Production of biosurfactant by a genetically-modified strain ofBacillus subtilis expressing green fluorescent protein

Abstract

Biosurfactant production was investigated using two strains ofBacillus subtilis, being one a reference strain (B. subtilis 1012) and the other a genetically-modified strain (B. subtilis W1012) made able to produce the green fluorescent protein (GFP). A new method based on oil displacement technique was set up to measure the biosurfactant level in the medium. Although the tested microorganisms showed similar results in terms of cell growth parameters, the recombinant strain, besides expressing GFP, exhibited an average yield of extracellular surfactant on biomass (Y B/X, av =239 mgB gx −1) more than twice that of the reference strain. The ability of the genetically-modified strain to simultaneously overproduce biosurfactant and GFP even at low cell concentration makes it an interesting candidate for possible use as a biological index-finger to monitor cell viability in bioremediation and oil recovery operations.