The deed conveying any lands authorized to be sold by any drainage district under the terms of Sections 51-33-49 through 51-33-57 and any lease contract leasing any lands of any drainage district authorized to be leased under the terms of said sections shall be made under the seal of the drainage district selling or leasing the same, and the same shall be signed for said drainage district by the president and secretary, respectively, of the board of commissioners of the drainage district so selling or leasing the same.