The phylogenetic tree of class B metallo-β-lactamase sequences. The protein sequences of SPS-1 and other selective metallo-β-lactamase were download and analyzed by Phylogeny.fr. The sequence include SPS-1 (WP_013255389.1), BcII(M11189), CcrA(M63556), IMP-1(S71932), VIM-2(AF191564), BlaB(AF189298), SPM-1(AY341249), NDM-1(JN420336), GIM-1(AJ620678), SIM-1(AY887066), DIM-1(GU323019), TMB-1(FR771847), Bla2(CP001598), KHM-1(AB364006), CphA(X57102), Sfh-1(AF197943), ImiS(Y01415), L1(AB294542), FEZ-1(Y17896), BJP-1(NP772870), AIM-1(AM998375), THIN-B(CAC33832), GOB-1(ABO21417), CAU-1(CAC87665), CAR-1(Q6D395), SMB-1(AB636283), POM-1(ADC79555), CRB11(ACS83724). The line segment with the number ‘0.6’ shows the length of branch that represents an amount genetic change of 0.6.