Multiple sequence alignment of P. calidifontis α-amylase with the sequences of other putative amylases from P. arsenaticum (NC_009376.1), P. oguniense (CP003316.1), P. islandicum (NC_008701.1), P. aerophilum (NC_003364.1) and with T. tenax (NC_016070.1). The identical residues are highlighted with soid black. Four highly conserved regions I, II, III and IV contain the amino acids DVVNH, GFRLDVAHG, EHVGN and FLENHDTD respectively have been shown with bold lines ( ̶̶ ̶ ). Asterisks (*) indicate the conserved residues of conserved regions among all α-amylases.