After qualifying as such neither the commissioner nor any of the deputies, clerks, or employees of the department shall be interested in any mineral, oil, or gas business, mineral, oil, or gas brokerage firm, real estate company or any real estate brokerage firm, as director, stockholder, officer, member, agent or employee, or act as a broker or salesperson, or act as a co-partner or agent for any broker or brokers, or

salesperson or salespersons.