Genetically engineered Pseudomonas: a factory of new bioplastics with broad applications

New bioplastics containing aromatic or mixtures of aliphatic and aromatic m onomers have been obtained using genetically engineered strains of Pseudomo nas putida. The mutation (-) or deletion (Delta) of some of the genes invol ved in the beta -oxidation pathway (fadA(-), fadB(-) Delta fadA or Delta fa dBA mutants) elicits a strong intracellular accumulation of unusual homo- o r co-polymers that dramatically alter the morphology of these bacteria, as more than 90% of the cytoplasm is occupied by these macromolecules. The int roduction of a blockade in the beta -oxidation pathway, or in other related catabolic routes, has allowed the synthesis of polymers other than those a ccumulated in the wild type (with regard to both monomer size and relative percentage), the accumulation of certain intermediates that are rapidly cat abolized in the wild type and the accumulation in the culture broths of end catabolites that, as in the case of phenylacetic acid, phenylbutyric acid, trans-cinnamic acid or their derivatives, have important medical or pharma ceutical applications (antitumoral, analgesic, radiopotentiators, chemoprev entive or antihelmintic). Furthermore, using one of these polyesters (poly 3-hydroxy-6-phenylhexanoate), we obtained polymeric microspheres that could be used as drug vehicles.