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Abstract
Selection of the most biosurfactant producable microorganism was conducted in thi: investigation based on quantity and surface tension. Surface tension of biosurfactant 38.1 mN/m was successfully obtained using Nocardia amarae. Olive oil as a carbon source fo N. amarae had a great effect on the production of biourfactant. The yield of biosurfactan was maximized by increasing the concentration of olive oil. The maximum yield 0 biosurfactant (1.22 g crude extractll culture) was obtained at 30 ml/l olive oil concentratioJ Ammonium nitrate and yeast with 2.3:1 ratio was the optimum nitrogen source for N amarae that could provide the maximum biosurfactant yield (1.82 g crude extract! culture). Time incubation exhibited a significant influence on biosurfactant productiOJ using N. amarae. It was shown that increasing the incubation period up to 14 days led t< increase the biosurfactant yield to the maximum value (4.42 g crude extractll culture).Thc biosurfactant yield was maximized by increasing the shaking rate. Virtually, the maximun yield (4.4 g crude extractll culture) was obtained at shaking rate 150 rpm .The partia purified biosurfactant had a CMC 50 mg/l at 38 mN/m surface tension compared with the CMC of the two commercial chemical surfactant (EEC 221 and EEC 230) were 250 an( 10 mg/l at 47 mN/m and 40 mN/m; respectively. The produced biosurfactant using N amarae strain showed obviously a higher rate of water separation in kerosene-wate] model system at elevated temperature compared with the commercial chemical surfactan~ (EEC 221 and EEC 230)~ CMC of the purified biosurfactant was 50 mg/l at 43 mN/n surface tension. Purified biosurfactant has no carbohydrate content while the proteir content was 0.52 mg/g purified biosurfactimt. Additionally, the analysis showed that the biosurfactant contain C, H, N, S as 21.54, 7.43, 5.12, 23.56 %; respectively. On the othe] hand it was clearly depicted that the purified biosurfactant didn’t contain CI or Br. The mh f the purified biosurfactant was 356 and the chemical structure is supposed to be N-O- bi: (methylsulfonyl) hydroxylamine-cis-7- tetradecen-I-ol. The estimated mathematical mode provided a satisfactory representation of the biomass growth; biosurfactant production The average error of biomass growth and biosurfactant production were 10.2, 5.7% respectively.