In order to reduce polyhydroxyalkanoates (PHAs) production cost we propose the simultaneous production of PHAs and other high value-added products such as rhamnolipids (RLs). The aim of the certain project is to investigate the ability of non-pathogenic bacteria to produce PHAs and RLs simultaneously. Factors that affect both biosynthetic pathways will be detected (composition and concentration of carbon source, type of nitrogen source, C/N ratio) and the cultivation strategy will be selected (reactor operation in fed-batch or continuous mode). For the simultaneous production of PHAs and RLs renewable substrates of oily nature will be used such as wastes generated from oil-processing plants and industries (waste vegetable oils such as corn oil and olive oil) in order to design a low-cost production process. PHAs and RLs yields, composition, distribution and physicochemical properties will be determined for each set of experiments in order to link bioprocess optimization with the optimization of PHAs and RLs physicochemical properties and to evaluate the effect of environmental and culture conditions on them.