Studies of emulsifying properties and stability of the biosurfactant produced by Bacillus subtilis in cassava wastewater

Due to the high surface activity, low toxicity, and biodegradability lipopeptides produced by bacteria of the genus Bacillus are among the best biosurfactants known and studied. These compounds are mentioned as potential inputs for various industrial sectors. However, to allow their implementation in industrial processes, it is necessary stability under extreme conditions often associated with of such processes and the maintenance of their properties. The aim of this work was to study the stability of the biosurfactant produced by Bacillus subtilis strain LB5a grown in cassava wastewater in a pilot process. Stability studies were carried out by varying the temperature, PH, and salt (NaCl) concentration. Another study was the evaluation of their emulsifying index in mixtures of water with hydrocarbons and vegetable oils as well as the stability of the emulsions formed. The results showed that the biosurfactant was stable under all combination of temperature and time tested: 100 degrees C for 140 minutes and 121 degrees C for up to 60 minutes. It was also stable in concentrations of NaCl from 2.5 to 20%, and pH from 6 to 10. The biosurfactant showed higher values of emulsion index at 24 hours (EI24) to various cyclical and aliphatic hydrocarbons when compared with SDS. The vegetable oils emulsions were stable despite the fact that the profiles of fatty acid chain in the oils were different. All results described characterize these compounds as potential emulsifiers for different industrial applications.