Investigation of cellular hydrophobicity and surface activity effects of biosynthesed biosurfactant from broth media of PTCC 1561

Abstract

Biosurfactants as surface active molecules that are synthesized by microorganisms. These substances include many advantages in comparison with chemical surfactants. For instance they have lower toxicity, higher biodegradability, better environmental compatibility, higher foaming activity, and specific activity at extreme temperatures, pH ranges, and the ability to be synthesized from renewable feed stocksin. In this study, the production of biosurfactant, produced by PTCC 1561 was studied. This bactrium was grown in a nutrient broth medium and the production of biosurfactant was evaluated by the surface tension and emulisification index (E24), each 24 h. The production of biosurfactant was studied in different conditions, including time of incubation, temperature, aeration rate and presence of several additives containing mineral salts and hydrocarbons. Finally, the optimum condition for production of the biosurfactant was determined and the biosurfactant identity was investigated using chemical and spectroscopy methods. The maximum biosurfactant production by Pseudomonas aeruginosa PTCC 1561, was exhibited when it was grown in Brain Hearth Broth medium containing Fecl3, ZnSO4, FeSO4, starch and olive oil incubated in a 200 rpm shaker incubator at 37°C for 24 h . The structure of produced biosurfactant sugar-lipid was confirmed by chemical and spectroscopy methods. Key words: Biosurfactant, emulsification index, surface tension.