What are the limitations of Taq polymerase?

Despite the extensive application of Taq polymerase in PCR reaction, this enzyme still has some limitations.

• Low specificity: Taq DNA polymerase has a lower specificity than the normal ones. Mismatches nucleotides could be added to the sequence by Taq polymerase.
• Low fidelity: Taq polymerase does not have 3’ to 5’ exonuclease proofreading activity, therefore mismatches nucleotides could not be corrected.
• Bivalent cation requirement: Taq polymerase requires cofactors, such as Mg2+ ion, to work properly.