Ala. Code § 45-18-90.03

Bonds and notes of the authority shall constitute negotiable instruments and may be secured by a pledge of the revenues from which they are payable, by contracts binding the authority for the proper application of its revenues and the proceeds of such bonds and notes and by a nonforeclosable mortgage or deed of trust, a statutory mortgage lien on the facilities and other property out of the revenues from which the bonds and notes are payable. Bonds and notes of the authority may be issued under a trust indenture.