Co-polyesters of 3-hydroxybutyrate and 3-hydroxyvalerate were produced by Alcaligenes eutrophus H16 from valeric or propionic acid under both air and knallgas (80:20 H2:O2) atmospheres. Selectivity for poly-3-hydroxyvalerate (PHV) synthesis over poly-3-hydroxybutyrate (PHB) is favored under hydrogen, presumably because high NADH levels under knallgas inhibit breakdown of PHV monomer precursors to PHB precursors. Switching the atmosphere from knallgas to air and back again to knallgas was shown to change the bacterial metabolism back and forth, producing different monomer precursors for polymer synthesis. The experiments suggest that this metabolic switching may be used to produce polyhydroxyalkanoates with blocky regions within the polymer or polymer granules with shells of different polymer composition.
Bibliographical noteFunding Information:
This researchw as funded by the Consortium for Plant BiotechnologyR esearcha nd the Biological Process Technology Institute (BPTI). A. K. is a recipient of a fellowship supported by a NIH trainingg rant in biotechnology.