Introduction. Botulinum toxin, also called “miracle poison,” is one of the most poisonous biological substances known.[ 1 ] It is a neurotoxin produced by the bacterium Clostridium botulinum, an anaerobic, gram-positive, spore-forming rod commonly found on plants, in soil, water and the intestinal tracts of animals.otulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C 1, C 2, D, E, F and G).