The cell growth of D. caeni PO5 markedly increased (2.71 to 3.50 g/l) when the incubation temperature was 30-35 ˚C. Further increases in the incubation temperature resulted in a dramatically decreased cell growth of D. caeni PO5. Incubation temperature had an effect not only on cell growth but also on biosufactant production by D. caeni PO5. When the temperature was increased from 20 to 35 ˚C, the surface activity and biosurfactant yield increased as wall Increasing the incubation temperature above 35˚C resulted in a dramatic decrease of surface activity and biosurfactant yield, especially when the incubation temperature was >40 ˚C. This result is in agreement with that reported by Thavasi et al. (2008) who found that incubation temperature had a large effect on growth and biosurfactant produced by Bacillus megaterium and that the optimum temperature was 38 ˚C. In addition, the optimal temperature for rhamnolipid production by pseudomonas aeruginosa J4 and lipopeptide production by Selenomonas ruminantium CT2 has been reported to be 30 ˚C (Sammai et al. 2013a). From these results, we selected an incubation temperature of 30 ˚C foe subsequent experiments.