The state of Alabama is authorized to become indebted and to sell and issue interest bearing bonds, in addition to all other bonds of the state, in an aggregate principal amount not exceeding $15,000,000. Of the proceeds derived from the sale of said bonds, $7,000,000 shall be used solely for the purpose of paying the expenses incurred in the sale and issuance thereof and for the acquisition, construction, equipment and improvement of mental health facilities, including security medical facilities for persons requiring security during treatment. The improvement of a facility shall be deemed to include the renovation, modernization, remodeling, and equipment of existing facilities and the construction of additions thereto; and the construction of a facility shall be deemed to include the acquisition of sites and equipment therefor. Proceeds in the amount of $2,000,000 derived from the sale of bonds provided for herein shall be used solely for the purpose of paying the expenses incurred in the sale and issuance thereof and for the acquisition, construction, equipment and improvement of a seed technology center at Auburn University and a foundation seed processing facility at Headland, Alabama. Of the proceeds derived from the sale of said bonds $6,000,000 shall be used for the purpose of paying the interest incurred in the sale and issuance of said bonds and for acquisition, construction and equipment of capital improvements, including, without limitation a facility or facilities for the housing, training, education and rehabilitation of prisoners. Said bonds shall be sold only at a duly advertised public sale or sales, upon sealed bids or at auction, to the bidder whose bid reflects the lowest total net interest cost to the state for the bonds offered for sale and shall be sold at not less than their face value plus accrued interest thereon. Said bonds shall be direct general obligations of the state, and for the prompt and faithful payment of the principal thereof and the interest thereon the full faith and credit of the state are hereby irrevocably pledged. The bonds issued under this amendment and the income therefrom shall be exempt from all taxation in the state. The legislature shall adopt appropriate enabling legislation to carry out the intent and purpose of this amendment.