Why is there DNA in the no-template control reaction when using the standard REPLI-g procedure, but not when using the UltraFast procedure?

In no-template (negative) control reactions, primer-dimers can form. The highly processive Phi29 DNA Polymerase will extend these primer-dimers leading to unspecific amplification products during the long incubation time with the standard REPLI-g procedure. Amplification in no-template controls takes place much more slowly than the amplification of template DNA. Using the REPLI-g UltraFast Mini Kit, the incubation time is too short to allow the extension of primer-dimers.

In any case, non-specific amplification products will not compromise results in downstream genetic analysis and do not appear if template DNA is present.