The aim of the present study was to propose a low-cost method for the production of a
biosurfactant by the yeast Candida sphaerica
and assess its toxicity and phytotoxicity. The medium
was formulated with distilled water supplemented with residue from a soy oil refinery (5%) and corn
steep liquor (2.5%) as substrates. These two products were the sources of carbon and nitrogen as well
as mineral elements to encourage the growth of the microorganism and production of a biosurfactant.
The isolated biosurfactant yield was 6.364 g/l. The biosurfactant exhibited an excellent ability
to reduce surface tension (26 mN/m) and demonstrated no toxicity against seeds of Brassica oleracea
and Solanum gilo
or the micro crustacean Artemia salina
employed as a bioindicator.
The biosurfactant exhibited no antimicrobial activity against the fungi and bacteria tested.
The promising results obtained in this study indicate the feasibility of producing
biosurfactants from powerful non-toxic organic residues and their application in the bioremediation of
contaminated soil and water.