Bioemulsifier-producing Aspergillus niger MYA 135: effect of culture conditions

Abstract

Bioemulsifiers are surface-active molecules synthetized by microorganisms, which play an important physiological role in hydrocarbon degradation. Few reports have shown the bioemulsifier production by filamentous fungi being the amount, quality and nature dependent not only on the microorganism but also on the culture conditions. Bioemulsifiers have the advantages of biodegradability, low toxicity, effectiveness and these properties enable their wide application on bioremediation, food, cosmetic and pharmaceutical industries, etc. The aim of this work was to study the bioemulsifier production by Aspergillus niger MYA 135 under different culture conditions. Methods: The bioemulsifier production was conducted in mineral medium during 96 hours, at different initial pH and with the addition of CaCl2 or FeCl3. The emulsification index was determinated after 24 h (E-24) in supernatants using kerosene as immiscible liquid. E-24 was estimated as the height of the emulsion layer divided by the total height and multiplied by 100. Results and conclusions: Bioemulsifier production reached maximum levels at 2 days of cultivation suggesting that its accumulation was growth-associated. Although all the emulsions were stable, the maximum values of E-24 were obtained at initial pH 2 (60.0 ± 0.71 %) and with the addition of FeCl3 (50.5 ± 0.70 %).This work was supported by grants PIP 6062 & PICTO 761