Strand-displacement activity is essential to most isothermal techniques, and all of our relevant DNA polymerases exhibit strong strand-displacement activity. The most important parameter for choosing an isothermal polymerase is desired reaction temperature.
Many isothermal applications use elevated temperature (> 50°C) and, for these, a thermophilic DNA polymerase is required. The large fragment of Bacillus stearothermophilus polymerase I (Bst DNA Polymerase, Large Fragment; NEB #M0275) has long been the enzyme of choice for these applications, however, NEB has recently developed an improved version of this polymerase, Bst 3.0 (NEB #M0374) for more robust isothermal amplification. For high-throughput and diagnostic applications requiring room-temperature setup and high reproducibility we recommend the WarmStart® version of Bst 2.0 (NEB #M0538). If 5′3′ exonuclease activity, rather than strand displacement activity, is desired, we also offer the full-length Bst DNA Polymerase (NEB #M0328) for these applications.
Our mesophilic DNA polymerases are appropriate for lower temperature reactions. The exo- variant of the E. coli DNA Polymerase I Klenow fragment (NEB #M0212) and large fragment of Bsu DNA Polymerase (NEB #M0330) are good options for many of these applications. If extreme processivity or proofreading exonuclease activity are desired, phi29 DNA Polymerase (NEB #M0269) is the enzyme of choice.