The kinetics of P(3HB-co-4HB) production by
C. necator strain A-04 was also investigated in detail; the synthesis of
4HB units was growth-associated under nitrogen-sufficient
conditions. Fig. 5 shows the effect of the C/N ratio on the relationship
between specific growth rate and specific production rate of PHAwhen
the ratio of γ-hydroxybutyric acid in the feed was between 50 wt.% and
95 wt.%. The synthesis of 3HB units was enhanced under nitrogendeficient
conditions. The mole fraction of 4HB units could be changed
from0 to 70mol% by adjusting the ratio of substrate and themole ratio
of C/N. The total P(3HB-co-4HB) content was 71 wt.% with a 4HB unit
mole fraction of 30 mol% in the copolymer (83).