| Summary: | The relevance of this work lies in the fact that it is the first time that corn steep liquor (CSL) has been proposed as a unique source of nutrients for producing biosurfactants in a controlled fermentation and <i>Aneurinibacillus aneurinilyticus</i>, isolated from CSL, has been evaluated for producing extracellular and cell-bound biosurfactants in a controlled fermentation, using secondary raw materials as a source of nutrients. In the present study, <i>A. aneurinilyticus</i> was inoculated into the culture medium containing sterilized CSL solutions (100–400 g L<sup>−1</sup>) and incubated using different temperatures (20–60 °C) and fermentation times (8–30 days). The dependent variables under study were the concentration of extracellular biosurfactants and cell-bound biosurfactant production in terms of critical micellar concentration (CMC), as well as the C/N ratio for cell-bound biosurfactant extracts. It was observed that CSL could increase the concentration of extracellular biosurfactants produced by A. <i>aneurinilyticus</i> if these were fermented during 19 days at 40 °C, using 250 g L<sup>−1</sup> of CSL; a mean value of 6 g L<sup>−1</sup> for extracellular biosurfactants and favorable CMC concentrations enabled the detection of cell-bound biosurfactant extracts under these conditions. Hence, these conditions could be considered optimal for producing both extracellular and cell-bound biosurfactants from CSL.
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