Section 6. The commissioner may, with the approval of the public health council, appoint assistant directors of divisions and epidemiologists, inspectors and other necessary employees. Persons appointed hereunder shall be subject to chapter thirty-one. The commissioner may require that a physician to be appointed under this section be certified as to his qualifications by one of the physicians' specialty boards approved by the Council on Medical Education and Hospitals of the American Medical Association.

The commissioner, with the approval of the public health council, may appoint a treasurer for each institution, who shall give bond for the faithful performance of his duties, and may appoint a superintendent, physicians, registered nurses, licensed practical nurses, student nurses and other employees necessary for the proper administration of the affairs of the institution under the jurisdiction of the department and may incur all expenses necessary for the maintenance of the institutions. Subject to the bylaws of an institution under the control and supervision of the department, the commissioner may admit to the medical staff thereof physicians and other providers of health care who are not compensated by the commonwealth as either salaried employees or consultants. Such physicians and other providers of health care may directly bill patients and their health insurers or other third-party payors for the clinical services they furnish to patients at such institutions.

The superintendent of each hospital or other institution established in the department may act on behalf and in the place of the appointing authority for any action taken under the provisions of sections fifty-three to fifty-seven, inclusive, of chapter thirty and for any action taken under sections nine A, nine B and nine D of chapter thirty and sections forty-three, forty-five and forty-six A of chapter thirty-one, relative to the discharge, removal, suspension and lay-off of a person. For all other purposes, the commissioner shall be the appointing authority; provided, however, that he may delegate preliminary authority to negotiate collective bargaining agreements and other matters relative to the right of employees to organize, negotiate and bargain with employers under section five of chapter one hundred and fifty A and section one hundred and seventy-eight F of chapter one hundred and forty-nine and other applicable statutes.