Physiochemical characterization of a biosurfactant produced by bacteria isolated from pharmaceutical process water

Abstract

The study was performed on samples from pharmaceutical process water. Only strains presumed to produce biosurfactants were selected depending on microbiological analyses. So, the main objective of this investigation was the isolation, identification and characterization of some microorganisms producing biosurfactants. These characteristics were compared with previous references. The capacity and conditions of biosurfactant production were determined via several tests such as the rate of biomass after incubation, pH, surface tension and emulsification index. Four strains have been identified, namely Pseudomonas Spp1, Pseudomonas Spp2, Flavobacterium spp and Serratia liquefaciens. The results obtained showed that the selected bacteria could produce biosurfactants with significant surface properties except for Pseudomonas Spp2. They were characterized in terms of structure, surface tension, emulsification capacity, thermal, and chemical stability. In addition, the emulsifying capacities were found to be very attractive; the best results were obtained for the products extracted from Pseudomonas Spp1, which were equivalent to those obtained from the reference (Bacilllus subtilis). Furthermore, all the biosurfactants have good thermal stability. However, their properties seem to be sensitive to pH; a basic pH leads to a lowering of the surface tension and an increase of the emulsifying capacity. Based on the spectral characteristics, the biosurfactants produced mainly by the isolated strains were found as glycolipid types.