Section 3. The commissioner shall be sworn to the faithful performance of his official duties. The commissioner shall not own, or be in the employ of, or own any stock in any regulated industry company, nor shall he be in any way directly or indirectly pecuniarily interested in or connected with any such regulated industry company or in the employ or connected with any person financing any regulated industry company. The commissioner shall not personally or through any partner or agent render any professional service or make or perform any business contract with or for any regulated industry company, nor shall he directly or indirectly receive any commission, bonus, discount, present, or reward from any regulated industry company. For the purposes of this section, a regulated industry company shall be defined as any corporation, city, town or other governmental subdivision, partnership or other organization, or any individual engaged within the commonwealth in any business which is, or the persons engaged in which are, in any respect made subject to the supervision or regulation of the department by any provision of law except chapter 110A and chapter 651 of the acts of 1910, as amended.