Nitrite inhibition of Clostridium botulinum: electron spin resonance detection of iron-nitric oxide complexes.

Vegetative cells of Clostridium botulinum were shown to contain iron-sulfur proteins that react with added nitrite to form iron-nitric oxide complexes, with resultant destruction of the iron-sulfur cluster. Inactivation of iron-sulfur enzymes (especially ferredoxin) by binding of nitric oxide would almost certainly inhibit growth, and thus is probably the mechanism of botulinal inhibition by nitrite in foods.