RT Journal Article SR Electronic(1) A1 Miles, Ellen M. A1 Miles, A. A.YR 1950 T1 The Relation of Toxicity and Enzyme Activity in the Lecithinases of Clostridium bifermentans and Clostridium welchii JF Microbiology, VO 4 IS 1 SP 22 OP 35 DO https://doi.org/10.1099/00221287-4-1-22 PB Microbiology Society, SN 1465-2080, AB SUMMARY: Crude preparations of the lecithinase of Clostridium bifermentans are lethal for mice. Their toxicity, haemolytic activity, and the power of liberating acid- soluble phosphorus from lecithin are neutralized by Cl. welchii α-antitoxin; in terms of lethal doses of Cl. welchii α-toxin and the bifermentans lecithinase, α-antitoxin is less than one five-hundredth as effective against the bifermentans lecithinase as against the α-toxin. In terms of in vitro lecithinase activity in standard conditions, equipotent amounts of lecithinase from three different strains of Cl. bifermentans were respectively 9, 60 and 75 times less toxic than the corresponding amount of Cl. welchii lecithinase. The toxicity of the Cl. bifermentans lecithinase therefore is determined, not only by its lecithinase activity, but by unknown factors that vary from strain to strain of the bacillus. These factors are not likely to be contaminating substances with a synergic or inhibitory effect, since the differences in toxicity were maintained in several preparations from each of the three strains studied. The analysis of the two antigenically related lecithinases from Cl. welchii and Cl. bifermentans provided no positive evidence against the hypothesis that the α-toxin of Cl. welchii is identical with the lecithinase., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-4-1-22