Table 2 presents the effect of the C:N ratio on cell groeth and biosufactant production from D. caeni PO5. The results show that the biosufactant concentration was higher and significantly different for C:N ratios of>40 than for C:N ratios of 535. There were no significant differences between C:N ratios of 40-60 in relation to biosurfactant production, but a C:N ratio of 65 presented a significant difference in relation to cell biomass. Several authors consider a nitrogen-limiting condition favorable to biosufactant production. Sammai et al. (2012c) commented that nutritional limitations direct cellular