An engineered DNA polymerase characterised in that the polymerase exhibits an enhanced ability to process nucleic acid in the presence of environmental and biological inhibitors compared to wild type DNA polymerase.
1. An engineered polymerase consisting of the amino acid sequence of SEQ ID NO: 2 and exhibiting at least a two-fold enhanced ability compared to the ability of the wild type Thermus aquaticus polymerase to process nucleic acid in the presence of humic acid at a concentration between 5 and 20%.
2. An engineered polymerase consisting of the amino acid sequence of SEQ ID NO: 4 and exhibiting at least a two-fold enhanced ability compared to the ability of the wild type Thermus aquaticus polymerase to process nucleic acid in the presence of humic acid at a concentration between 5 and 20%.
3. A kit for amplifying nucleic acid comprising an isolated, engineered polymerase according to claim 1 or claim 2 .