Biosynthesis of High Quality Polyhydroxyalkanoate Co‐ and Terpolyesters for Potential Medical Application by the Archaeon Haloferax mediterranei

Abstract

AbstractSummary: 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 (µmax.) and the maximum specific PHA production rate (qp 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 °C and narrow molecular mass distribution (polydispersity PDI = 1.5). Further, a PHA terpolyester with an increased 3HV fraction as well as 4‐hydroxybutyrate (4HB) building blocks was accumulated by feeding of whey sugars plus 3HV ‐ and 4HB precursors. Kinetic analysis of the process reveals a µmax. of 0.14 1/h and a qp 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 °C) and the onset of decomposition at 236 °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.