Detection of biosurfactant from hydrocarbon-degrading bacteria

Abstract

Biosurfactants are surface-active bio-molecules produced by bacteria, yeasts, and fungi. The characteristics of high surface activity, low toxicity, high biodegradability, and environmental friendly make biosurfactant an alternative to chemically synthesized surfactants. In this study, fourteen bacteria isolates isolated from various hydrocarbon contaminated sites were screened for biosurfactant production. Blood agar hemolysis, microplate test, drop-collapse test and emulsification activity test were carried out to screen for biosurfactant-producing ability. Sodium dodecyl sulphate (SDS) and distilled water were used as positive control and negative control, respectively. Blood agar hemolysis revealed that eight isolates showed hemolysis whereas all isolates showed positive results in microplate test. All isolates scored positives for drop-collapse test with ranges of time from one minute to four minutes for the culture to collapse. Four isolates were found as prominent biosurfactant producer with emulsification index E24 ~50%. As conclusion, three isolates which were UKMP-8T, UKMP-12T and UKMP-14T showed positive results for all the biosurfactant detection tests.