Properties and biodegradation of a bioemulsifier from Corynebacterium hydrocarboclastus

Abstract

An extracellular polymer was produced by continuous fermentation of Corynebacterium hydrocarboclastus on kerosene in a 24 liter reactor. This polymer was composed of protein, lipid, and carbohydrates. The polymer possessed surface active properties, and had two critical micelle concentrations. Its effectiveness was quite comparable to the effectiveness of synthetic surface active agents such as Tween 80 and Span 20; however, its efficiency was much lower. The polymer also had emulsifying properties. Maximum emulsification was obtained at pH 6. The emulsifying properties were unaffected by high salt concentration [up to 5% (w/v) in Na+], and tolerated a water hardness up to 5,000 ppm. A 2 hr treatment of the polymer at temperatures higher than 65 degrees C resulted in a loss of its emulsifying properties. Two microorganisms, named SLYS and Y, isolated from soil, were able to grow on the polymer as sole carbon and energy source, thus proving its biodegradability. SLYS was tentatively identified as Flavobacterium breve and Y as Flavobacterium devorans.