The thermogenic curves of metabolism of the four strains of Escherichia coli pUC19cab/JM109, pUC19cab/XL-IBlue, JM109 and XL-IBlue were determined using the LKB-2277 BioActivity Monitor and the ampoule
method at 37�C. The pUC19cab/JM109 and pUC19cab/XL-IBlue are recombinant E. coli strains bearing the same foreign plasmid pUC19cab, which confers the ability to produce polyhydroxyalkanoates (PHAs). The
yield of PHAs of pUC19cab/XL-IBlue was higher than that of pUC19cab/JM109. XL-IBlue and JM109 were the host bacteria. The
heat flow of these strains was XL-Blue≈JM109>pUC19cab/JM109>pUC19cab/XL-IBlue. These results indicate an obvious interrelation
between the PHAs production and the heat flow rate of E. coli strains.