DNA nuclease able to digest short and long DNA substrate. Is resistant to ionic strength and thus active at high salt concentration. Requires Ca(2+) or Mg(2+) for catalytic activity and the maximum activity is achieved when both of these ion species are present. Harbors two domains: an N-terminal domain, that exhibits DNase activity, and a C-terminal domain, comprising a duplicate DNA binding helix-hairpin-helix motif. The C-terminal domain is responsible for the enzyme's resistance to high ionic strength, it acts as a facilitator for DNA binding at high salt concentrations. Thioalkalivibrio sp. K90mix is adapted to extreme salt concentrations and grows at salinities up to 4 M of NaCl. Belongs to the DNase I family.