Applied and Environmental Microbiology, August 1999, p. 3265-3271, Vol. 65, No. 8
Institute of Biotechnology, ETH
Hönggerberg, CH-8093 Zürich, Switzerland
Received 1 March 1999/Accepted 12 May 1999
In order to scale up medium-chain-length polyhydroxyalkanoate
(mcl-PHA) production in recombinant microorganisms, we generated and
investigated different recombinant bacteria containing a stable regulated expression system for phaC1, which encodes one of
the mcl-PHA polymerases of Pseudomonas oleovorans. We used
the mini-Tn5 system as a tool to construct
Escherichia coli 193MC1 and P. oleovorans POMC1, which had stable antibiotic resistance and PHA production phenotypes when they were cultured in a bioreactor in the absence of
antibiotic selection. The molecular weight and the polydispersity index
of the polymer varied, depending on the inducer level. E. coli 193MC1 produced considerably shorter polyesters than
P. oleovorans produced; the weight average molecular weight
ranged from 67,000 to 70,000, and the polydispersity index was 2.7. Lower amounts of inducer added to the media shifted the molecular
weight to a higher value and resulted in a broader molecular mass
distribution. In addition, we found that E. coli 193MC1
incorporated exclusively the R configuration of the
3-hydroxyoctanoate monomer into the polymer, which corroborated the
enantioselectivity of the PhaC1 polymerase enzyme.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Engineering of Stable Recombinant Bacteria for
Production of Chiral Medium-Chain-Length
Poly-3-Hydroxyalkanoates


*
Corresponding author. Mailing address: Institute of
Biotechnology, ETH Hönggerberg, CH-8093 Zurich, Switzerland.
Phone: 41-1-6333402. Fax: 41-1-6331051. E-mail:
bw{at}biotech.biol.ethz.ch.
Present address: Centro de Investigaciones Biologicas, CSIC, 28006 Madrid, Spain.
Present address: Institute of Biology, Faculty of Natural
Sciences, 21000 Novi Sad, FR Yugoslavia.
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