The enzymes PhaA (ketothiolase), PhaB (acetoacetyl-
CoA reductase) and PhaC (PHB synthase) of the Gramnegative
bacterium R. eutropha H16 were expressed in
the cytosol of the diatom P. tricornutum to test whether
polyhydroxybutyrate (PHB) can be produced in a microalgal
system. Initial in vivo localization studies with GFP
fusion proteins demonstrated that all three enzymes are
expressed in the heterologous system and accumulate
within the cytosol (Figure 1). P. tricornutum cells that
were co-transfected with sequences for all three