If it shall be decided at said meeting in the manner aforesaid, to do said work, the directors shall proceed to let the same out to the lowest and best bidder; provided, however, that said directors shall have the right to reject all bids, if the same be deemed too high. No director shall, either directly or indirectly, become a contractor for the building or repairing of any levee or public work contemplated by sections 245.285 to 245.545, nor have any interest therein, present or remote; and any director so offending shall, upon conviction, be punished by imprisonment in the penitentiary not exceeding five years.