Author(s): Luna JM, Rufino RD, Sarubbo LA, CamposTakaki GM
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Abstract The development of less toxic, biodegradable, surfactants, such as biosurfactants, is a key strategy for acquiring environmentally friendly compounds. The aim of the present study was to employ an optimised medium containing 9\% ground nut oil refinery residue and 9\% corn steep liquor for the production of a biosurfactant by Candida sphaerica. Fermentation was carried out at 28 °C and 200 rpm for 144 h. Biosurfactant yield was 9 g/l. The biosurfactant reduced the surface tension of the medium to 25 mN/m, with a critical micelle concentration of 0.025\%. The product demonstrated stability with regard to surface tension reduction and emulsification in a range of temperatures (5-120 °C) and pH values (2-12) as well as tolerance to high concentrations of NaCl (2-10\%). Hydrophobicity tests indicate two possible insoluble substrate uptake mechanisms: direct interfacial uptake and biosurfactant-mediated transfer (cell contact with emulsified or solubilised hydrocarbons). The biosurfactant was characterised as an anionic glycolipid consisting of 70\% lipids and 15\% carbohydrates and demonstrated no toxicity to the microcrustacean Artemia salina or the vegetables Brassica oleracea, Solanum gilo, Lactuca sativa L. and Brassica oleracea L. The biosurfactant recovered 95\% of motor oil adsorbed to a sand sample, demonstrating considerable potential for use in bioremediation processes, especially in the petroleum industry. Copyright © 2012 Elsevier B.V. All rights reserved.
This article was published in Colloids Surf B Biointerfaces
and referenced in Journal of Bioremediation & Biodegradation