SYNTHESIS AND PRODUCTION OF POLY(3-HYDROXYVALERIC ACID) HOMOPOLYESTERBY CHROMOBACTERIUM-VIOLACEUM

Chromobacterium violaceum DSM 30191 accumulated a homopolyester of 3-h ydroxyvaleric acid (3HV) up to 65% of the cellular dry matter during c ultivation in fed-batch cultures with valeric acid as sole carbon sour ce and during cell starvation of the nitrogen source. From fructose, g luconate, propionate or hexanoate a homopolyester of 3-hydroxybutyrate (3HB) was accumulated. Poly(3HV) homopolyester was also accumulated b y two different strains of C. vio violaceum, whereas two other strains of C. violaceum and three strains of Janthinobacterium lividum accumu lated poly(3HB-co-3HV) copolyesters from valerate. The composition of the biosynthetic poly(3HV) was confirmed by various nuclear magnetic r esonance spectroscopic methods. Differential scanning calorimetry anal ysis of four poly(3HV) samples that were isolated from different batch es of cells revealed glass transition temperatures between -10 and -12 -degrees-C and melting points between 107 and 112-degrees-C. Viscosity measurements gave intrinsic viscosities between 62.5 and 124.8 x 10(- 2) dl/g for these samples, indicating approximate relative molecular m asses between 60000 and 145000 of the biosynthetic poly(3HV).