-PCR screening with bacterial colonies as templates or with Taq DNA polymerase from different sources. A. Colony gradient PCR performed at indicated annealing temperatures using bacterial colonies carrying hGH WT or hGH mutant (D112K or D112G) plasmid to detect their Tc. B. Twenty colonies screened at Tc after SDM. The sequencing results are represented by M (desired mutant) and W (wild type), respectively. C. Gradient PCR at the indicated annealing temperatures with Taq DNA Polymerases from different companies, such as Fermentas and Takara.