Effect of initial pH
Certain microorganisms have the ability to grow and produce biosufactants in a wide pH range. This renders possible the microbial production of surfactant for in situ applications, such as bioremediation and cnhanced oil recovery (Mulligan 2005). Based on our results, D, caeni PO5 is able to grow under a pH range of 5.0-9.0; in our study, the highest levels of cell growth were recorded at pH values ranging from 6.5 to 8.5 (data not shown). However, the highest levels of biosufactant production were obtained at pH 7.0. Other pH values were accompanied by decresed biosufactant production, especially at pH≥8.5 and ≤6.0.