ADDITIONAL SECURITY.

(a) At the board's discretion, the bonds of an authority may be additionally secured by a deed of trust or mortgage lien on part or all of the physical properties of the authority, and franchises, easements, leases, and contracts and rights relating to those properties. The trustee may operate the properties, sell the properties for payment of the bonds or interest on the bonds, and exercise all other powers and authority for the further security of the bonds.

(b) The trust indenture, regardless of the existence of the deed of trust or mortgage lien on the properties, may:

(1) contain provisions prescribed by the board for the security of the bonds and as preservation of the trust estate and for the modification or amendment of those provisions;

(2) condition the right to spend authority money or sell authority property on the approval of a registered professional engineer or architect and provide for the manner of selecting the engineer or architect; and

(3) provide for the investment of funds of the authority.

(c) A purchaser under a sale under a deed of trust or mortgage lien is the absolute owner of the properties, facilities, and rights purchased and may maintain and operate the properties.