Abstract: An antibiotic composition is provided for use in decontaminating biological tissue, for example, graft tissues for transplantation or preparation for terminal sterilization. The antibiotic composition is a physiological solution includes a lantibiotic, such as nisin. The antibiotic solution is effective to substantially inhibit bacterial growth of at least one type of gram-positive bacteria while substantially maintaining the physiological characteristics of the tissue. The method may include contacting the tissue with the antimicrobial composition at a temperature and for a period of time effective to substantially inhibit bacterial growth of the at least one type of gram-positive bacteria while substantially maintaining the physiological characteristics of the tissue.