Selected or recombinant PHA-producing microorganisms that give higher yields require a sterile process (from medium to product formation). The solvents and their final disposal increase the final product price. A number of studies have considered the use of residues and by-products as substrates: in particular, materials derived from the food industry, due to their composition of readily degradable organic molecules. In these cases, the PHA yield is lower than with pure substrates, but with the advantage of reduced medium costs (1).