Abstract
In the recent decade, biosynthesis of the degradable biopolymers
polyhydroxyalkanotes in transgenic yeasts became an important research
task. Most research strategies depend on either metabolic engineering
or molecular approaches. In the present work, research compared PHA
biosynthesis in two types of yeasts; Saccharomyces cerevisiae and a
non-convenient Kloeckera spp.Yeast strains were equipped in their
cytoplasm with the phaABCRe operon containing genes phbA, phbB and phbC
of the PHA biosynthetic pathway of Ralstonia eutropha , which encode
â-ketothiolase, NADPH-linked acetoacetyl-CoA reductase and PHA
synthase, respectively. The transgenic strains Saccharomyces cerevisiae
and Kloeckera sp. were able to produce PHA. The maximum content of the
polymer detected in the recombinant strain INVSc1/PHA1 was 2.68 % and
only poly-3-hydroxybutyrate (PHB) accumulated. However, the
non-conventional transgenic strain KY1/PHA was able to accumulate as
maximum of 7.06 % of the copolymer
poly-(3-hydroxybutyrateco-poly-3-hydroxyvalerate) (PHV). Western blot
analysis confirmed expression of the phaABCReoperonin the transgenic
yeast strains. The nature of the PHA thus produced by all tested
strains was analyzed by 1H and 13C nuclear magnetic resonance (NMR)
spectroscopy.