Metabolic engineering of poly(3‐hydroxybutyrate‐ <i>co</i> ‐3‐hydroxyvalerate) composition in recombinant <i>Salmonella enterica</i> serovar typhimurium

Abstract A recombinant strain of Salmonella enterica serovar Typhimurium (mutant in propionate‐activation activity) was metabolically engineered to control the composition of poly(3‐hydroxybutyrate‐ co ‐3‐hydroxy‐ valerate) (PHBV), a polyhydroxyalkanoate copolymer with commercially desirable properties. A gene ( prpE ) encoding propionyl‐CoA synthetase was placed under the control of the IPTG‐inducible taclacUV5 promoter (P taclacUV5 ) while the polyhydroxyalkanoate synthesis operon ( phaBCA ) from Acinetobacter sp. RA3849 was coexpressed under the control of the arabinose‐inducible araBAD promoter (P BAD ). S. enterica, harboring both constructs, was grown in medium containing a fixed substrate concentration and the composition of the copolymer was varied between 2 mol% and 25 mol% 3‐hydroxyvalerate by controlling the IPTG level in the medium. This “dial‐a‐composition” system should find application in cases where the substrate concentration of a feedstream for PHBV bioplastic production is not adjustable. © 2001 John Wiley &amp; Sons, Inc. Biotechnol Bioeng 76: 108–114, 2001.