Methods of making polyhydroxyalkanoates comprising 4-hydroxybutyrate monomer units

摘要

The PHA biosynthetic pathway is combined with a succinic semialdehyde metabolic pathway that metabolizes succinic semialdehyde via a 4-hydroxybutyryl-CoA intermediate in order to produce high levels of PHA comprising 4HB monomer units. This combination is particularly useful, in part, because the PHA biosynthetic pathway is well known and has been expressed to produce P(3HB) to levels as high as 70-80% of the cell dry weight, while the succinic semialdehyde metabolic pathway is also well known, and the combination of the two pathways means that production of PHAs comprising 4HB monomer units does not depend on immediate precursors of 4-hydroxybutyrate. Rather, the production of the PHAs comprising 4HB monomer units can occur simply from the extraction of succinate or succinyl-CoA from the citric acid cycle when the host cell is grown on an inexpensive carbon source such as glucose.