Temperature-induced expression of phb genes in Escherichia coli and the effect of temperature patterns on the production of poly-3-hydroxybutyrate

The plasmid pNDTM2 was constructed to contain the p_R-p_L promoter and the phbC, A, and B genes which code for PHB synthase, β-ketothiolase, and acetoacetyl-CoA reductase, respectively. This plasmid was transformed into Escherichia coli XL1-Blue. The effect of several thermal induction patterns on the production of poly-3-hydroxybutyric acid (PHB) was investigated based on fermentor experiments. Based on the experimental results with different induction patterns, it was found that the temperature should be controlled at 34°C during the initial 10 h of cultivation to promote cell growth, and then it should be increased to 40°C for induction. Then the temperature should be lowered to 37°C after 5 h to relieve the effect of the heat shock.