                A.Yataghene 1 , M. Abouseoud 2 , R. Maachi 1 , A. Amrane 3 1 Laboratoire Génie de la Réaction, Université Houari Boumediene, Institut de Chimie Industrielle, Alger, Algeria. E%mail: a.yataghene@yahoo.fr 2 Centre Universitaire Yahia Fares de Médéa, Département Génie des Procédés Pharmaceutiques, Institut des Sciences de l’Ingénieur, Ain Dahab, Médéa, 26000, Algeria. E%mail: Mahmoud103@hotmail.com 3 UMR CNRS 6226 – Equipe CIP (Université de Rennes 1 – ENSCR) ENSCR, 35700, Rennes, France. E%mail: abdeltif.amrane@univ%rennes1.fr The production of biosurfactant by cells of Pseudomonas fluorescens Migula 1895, using the following Carbon (glucose, olive oil and hexadecane) and Nitrogen (urea, NH 4 NO 3 , KNO 3 and NH 4 Cl) sources were examined in this work. Olive oil and NH 4 NO 3 as carbon and nitrogen sources were found to give the optimal yield of biosurfactant production (9 g L %1 ) for an optimal C/N ratio of 10/1, and led to a decrease of the surface tension of the culture medium from an initial value of 69 mN m %1 to 30.5 mN m %1 at the end of culture. The critical micellar concentration was found to be 290 mg L %1 . Interfacial tension value was low with vegetable oil (2.5 mN m %1 with Sunflower oil) and high in case of aromatic oil (17.5 mN m %1 with toluene). The stability of the emulsion produced against sunflower oil was very stable during several days; leading to an emulsification index E24 of 80%. Wettability is also a useful parameter to characterize biosurfactants. The decrease of the contact angle reflects an improvement in the degree of wetting.   Due to the features of high surface activity and biodegradability, biosurfactants produced by a variety of microorganismes have been studied extensively in recent years (Van Hamme et al 2006). Biosurfactants are amphiphilic compounds and are mainly classified into four categories based on the hydrophilic part: glycolipid type, fatty acid type, lipopeptide type and polymer type. Biosurfactants production is an important area of research, owing to the large number of potential applications, especially as substitutes for synthetic surfactants in oil and other industries (Banat et al 2000; Mulligan 2005).They can be used as emulsifiers, de%emulsifiers, wetting agents, foaming agents, functional food ingredients and detergents (Kosaric 1992). The major factors restricting the commercial viability of biosurfactants are the low yield and high production cost (Mukherjee et al 2006; Fiechter 1992). Pseudomonas are the best% known bacteria capable of utilizing hydrocarbons as carbon and energy sources and producing biosurfactants to enhance the uptake of such immiscible hydrophobic compounds (Al%Tahhan et al 2000; Rahman et al 2002). However, the available literature shows a lack of studies dealing with biosurfactant production by considering the use of carbon sources other than hydrocarbons.