Moreover, Sinskey and Peoples also proposed that Alcaligenes eutrophus had at least two P-ketothiolase and acetoace- tyl-CoA reductase enzymes. Thiolase and reductase enzymes, when they interact with either enoyl-CoA hydratase or epimerase or both, can lead to the formation of D(-)-3-hydroxybutyryl-CoA. In E.coli the expression of phbC alone results in a diminished amount of PHB synthesis and an insignificant rate of PHB polymerase activity. The absence of both phbA and phB genes of A. eutrophus leads to no synthesis of D(-)-3-hydroxybutyryl-CoA. Only when the three A. eutrophus genes, phbC-phbA-phbB, were present in E. coli, then greater than 50% of PHB production was observed. They also figured that PHB production was inhibited by the presence of nitrogen. Moreover, they proposed that the interaction of thiolase and/ or reductase with the polymerase was necessary for the polymerase to functio