Selection of the main micronutrients for the production of biosurfactant by an isolated Bacillus subtilis strain

Abstract

Biosurfactants possess various unique properties, such as good environmental compatibility, low toxicity, high selectivity, high biodegradability and are stable over a wide range of temperature, pH and ionic strengh. These advantages allow the substitution of chemically synthesized surfactants by those of biological origin in different industrial sectors, mainly for enhanced oil recovery. This study presents the influence of different micronutrients (B, Fe, Zn, Cu, Mn, Ca, Mo and Co) in biosurfactant production by Bacillus subtilis, LFB 732 strain, using very high polarization (VHP) raw sugar, as the one and only cost-effective carbon source. A Plackett-Burman design, with 12 tests, in replicate, was employed for screening eight mineral salts, which are regular constituents of fermentative medium, aiming to reduce the cost of the bioprocess. Batch fermentation experiments were carried out in shake-flasks at the controlled agitation speed of 150 rpm and temperature of 30°C, for 24 and 48 h. The experimental data revealed that Fe and Zn ions were the most important micronutrients in the fermentation broth for production of this biosurfactant and the absence of the others did not affected the production.