Impact of the surface properties of lactic bacteria on the stability of emulsions

Bacteria have physicochemical surface properties which depend on the chemical composition of the cell surface. These characters proceed from several type of physicochemical interactions and are involved in attachment processes of microorganisms to surfaces. Thus they are of interest in several areas, as biomedicine, formation of biofilms and adhesion to apolar surfaces. Moreover, food matrix are complex heterogeneous media, which structure settles on interaction forces between molecules (van der Waals, electrostatic or structural forces…). When bacteria are present in a matrix, it is probable that their surface interacts with the other constituents. So far, few studies have mentioned this subject. In order to understand the involvement of cells surface properties in a food matrix, the effect of surface properties of lactic bacteria on the stability of model emulsions were studied. The results showed that the choice of a bacterium according to its surface properties may have a strong impact on the stability and on the behavior of an emulsion

Degradation of Alkanes in Rhodococcus

Alkanes are widely distributed in the environment as they not only constitute the large fraction of crude oil but are also produced by many living organisms. They are saturated hydrocarbons of different sizes and structures, which pose a variety of challenges to degradative microorganisms due to their physicochemical properties, i.e., the extremely limited solubility and the high energy required for activation. The hydrophobic cell surface of Rhodococcus spp., the ability to produce biosurfactants, and the possession of a wide range of oxygenases allow coping with such challenges. In particular, monooxygenase enzymes are involved in the activation of alkanes by converting them into alcohols, which undergo a series of oxidation steps before being converted to fatty acids. Rhodococcus alkane monooxygenases belong to different families (i.e., AlkB-like monooxygenase, soluble di-iron monooxygenase, cytochrome P450), have different genetic organization, and are subject to different regulatory mechanisms, which are poorly known. Because of their long-term survival capacity, broad catabolic abilities, and effective contact mechanisms with hydrocarbon molecules, alkanotrophic Rhodococcus strains have biotechnology applications and potential in bioremediation and biotransformation reactions