Optimization of Bacillus Licheniformis DSM13 for Biosurfactant Production Using Response Surface Methodology

Biosurfactants are surface-active compounds that can reduce surface tension in both aqueous solutions and hydrocarbon mixtures, which in recent times have become more valuable due to their lower toxicity and are generally referred to as green or organic surfactants. Such products are much better than chemical surfactants in terms of their enhanced biodegradation rates and the bioavailability of organic contaminants. Fungi, yeast and bacteria are mainly capable of producing microbial biosurfactants. Bacteria, especially Bacillus, are one of the most frequently applied and studied biosurfactant producers. This study investigated the kinetics of cell growth, the production of biosurfactants as well as the effect of and interactions between the (A) pH within the range of 4.1 to 9.8, (B) glucose concentration between 3.0 and 36.9 g/l, (C) surface tension and (D) emulsification index to maximize biosurfactant production. The analysis was carried out using a central composite design (CCD) model with four factors and five levels. The optimized medium (pH=8 and glucose concentration = 38 g/l) decreased the surface tension to 60 mN/m and increased the product yield up to 2.7 g/l.