Preparation, characterization, and modification of poly-beta-hydroxyalkanoates from Pseudomonas oleovorans

Polymer production by P. oleovorans grown with various carbon substrates was investigated. Under the experimental conditions employed in this study, no limitation of nutrient was necessary to induce for this microorganism to produce polymers, but limiting nitrogen improved the polymer yield. The main repeating unit in polymers produced from n-alkanoic acids longer than heptanoic acid was either 3-hydroxyoctanoate or 3-hydroxynonanoate. Carbon sources examined for growth and PHA production were classified according to growth results. Both physical and chemical properties of the carbon substrate affected cell growth and PHA production. When a substituent was present, the better growth and PHA production were, the longer the separation between the carboxylic acid and the substituent was. Polymers containing various unusual groups such as olefin, nitrile, ester, bromine, alcohol, cyclohexane, and phenyl group were obtained by growing P. oleovorans wither either single carbon substrate or mixtures of two carbon substrates. Ninety-nine percent of repeating units in a PHA prepared from cells grown solely with 10-undecenoic acid, UND:, contained olefin group. PHAs produced from mixtures of two carbon substrates both of which support cell growth and PHA production were generally random copolymers with the exception of the polymer produced from mixtures of 5-phenylvaleric acid and either n-nonanoic acid, NA, or n-octanoic acid, OA. Many carbon substrates that support cell growth without PHA production were incorporated into the polymer when these substrates were co-fed to P. oleovorans with NA or OA. Polymers containing repeating units with bromine group could be prepared only when $\omega$-bromoalkanoic acids were fed in the presence of NA, but a polymer containing nitrile group were obtained when 11-cyanoundecanoic acid was fed in the presence of either NA or OA. PHAs containing unsaturated units were crosslinked by heating in the air or by heating with peroxides under nitrogen atmosphere to get rubber elastic products. Epoxidation of these polymers was also partially investigated