The production of botulinal toxin by a mixture of spores of Clostridium botulinum types A and B was evaluated in Cheddar cheese supplemented with L-arginine (1% wt/wt) and containing one of three levels of sodium chloride (0, 0.9, or 1.8%). Botulinal toxin was formed in cheeses containing an increased level of L-arginine (1%) and reduced levels of sodium chloride (0 or 0.9%). No toxin was formed in Cheddar with arginine and 1.8% salt or in any of the cheeses not supplemented with arginine. The pH increased from 5.05–5.2 to 5.7–6.0 in the cheeses with increased arginine, but the pH change alone did not permit growth of C. botulinum. Metabolism of arginine may also have promoted the synthesis of compatible metabolites for salt resistance. The results indicate that an important factor supporting growth of C. botulinum in cheese is the availability of L-arginine.

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