Synthesis of polyhydroxyalkanoates through the biodegradation of poly(cis-1,4-isoprene) rubber.

The search of alternative substrates for the synthesis of polyhydroxyalkanoates (PHA) has become an important factor in order to decrease the production costs. Therefore, the use of industrial by-products or waste materials as carbon and energy sources for different PHA-producing microorganisms has been evaluated during the last decades. Recombinant strains of Gordonia polyisoprenivorans VH2 harboring plasmid pAK68, which contains phaCAB from Ralstonia eutropha and plasmid pAK71 comprising phaC1 from Pseudomonas aeruginosa were evaluated for PHA production. Cultivations were performed in shake flasks, using different carbon sources under an N-starvation condition. Having in consideration the rubber degrading capability of the actinomycete, poly(cis-1,4-isoprene) was utilized as sole carbon source. After twenty days of cultivation the PHA content was analyzed using GC-MS. In cultures of G. polyisoprenivorans harboring pAK68, the detection of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) monomer units indicated the accumulation of the copolyester poly(3HB-co-3HV). This study proposes a recycling method for rubber waste through its biotransformation into bioplastic.