Thursday, August 2, 2007 - 9:00 AM
S155
Use of animal-free and dairy-free soy protein hydrolysate for toxin production by Clostridium tetani and Clostridium difficile
Arnold L. Demain, R.I.S.E., Drew University, HS-330, Madison, NJ 07940 and Aiqi Fang, Acambis, Sydney St., Cambridge, MA.
Tetanus is a life-threatening disease caused by Clostridium tetani. For over 50 years, vaccination with tetanus toxoid has been practiced to prevent the disease. Toxin is produced and inactivated, usually with formalin, to produce the toxoid. Immunization is completely effective and thus tetanus is rare in the West.. Toxin has been traditionally prepared by growth of C. tetani in media containing animal plus dairy products as sources of proteins, peptides and amino acids needed for good growth. When toxoid is made, it is often contaminated with formalin adducts of animal and dairy proteins and may contain undesirable contaminants such as the prion causing Bovine Spongiform Encephalopathy (Mad Cow’s Disease) or antigenic peptides that stimulate anaphylactic reactions. We found that a single soy peptone could replace both beef heart infusion and casein hydrolysate and even provide higher toxin titers. Furthermore, soy peptone could replace these materials in seed media and soy milk could replace cow’s milk as preservation menstrum. Optimum production of tetanus toxin did not require addition of pantothenic acid, thiamine, riboflavin, pyridoxine, biotin and uracil used by previous investigators. Furthermore, L-tyrosine and L-cysteine could be eminated from our medium without effect, making the medium (Hy-Soy, glucose, reduced iron powder and inorganic salts) much more economical. We further found that reduced iron powder plays a double role, i.e., releasing soluble iron sources and providing an insoluble surface. The soy peptone process was successfully scaled-up into 1 liter fermentors. Similar results were obtained in the process of making Clostridium difficile toxin.