Blosynthesis of high quality Polyhydroxyalkanoate co- and terpolyesters for potential medical application by the archaeon Haloferax mediterranei

Haloferax mediterranei was investigated for the production of two different high-performance polyhydroxyalkanoates (PHAs). A copolyester containing 6 mol-% 3-hydroxyvalerate (3HV) was produced from whey sugars as sole carbon source. The maximum specific growth rate (mu(max.)) and the maximum specific PHA production rate (q(p) (max)) were determined with 0.10 1/h and 0.15 1/h, respectively. The cells contained 72.8 wt.-% Of P-(3HB-co-6%-3HV) which featured low melting points between 150 and 160 degrees C and narrow molecular mass distribution (polydispersity PD1 = 1.5). Further, a PHA terpolyester with an increased 3HV fraction as well as 4-hydroxybutyrate (013) building blocks was accumulated by feeding of whey sugars Plus 3HV - and 4HB precursors. Kinetic analysis of the process reveals a mu(max.) Of 0.14 1/h and a q(p) (max.) of 0.23 1/h, respectively. The final percentage Of P-(3HB-co-21.8%-3HV-co-5.1%-4HB) in biomass amounted to 87.5 wt.-%. Also this material showed a narrow molecular mass distribution (PDI = 1-5) and a high difference between the two melting endotherms of the material (between 140 and 150 degrees C) and the onset of decomposition at 236 degrees C. The accomplished work provides viable strategies to obtain different high-quality PHAs which might be potential candidates for application in the medical and pharmaceutical field.