Germination, growth, and toxin production of nonproteolytic Clostridium botulinum as affected by multiple barriers

The effect of combinations of pH (6.5, 5.75), NaCl (0.25, 1.75%), and incubation temperatures (7, 13 degreesC) on spore germination, outgrowth, and time to toxicity of nonproteolytic Clostridium botulinum was examined in a broth system. Spores of four toxin type E and nonproteolytic type B were inoculated (10(4) /ml) into Tryptone Peptone Glucose Yeast Extract (TPGY) broth. Cultures were monitored for three weeks, or until toxin was detected. A modified FSIS-amplified ELISA (comparable in sensitivity to the mouse bioassay) was used to screen cultures for neurotoxin. Combinations of the most inhibitory level for each barrier reduced the degree and rate Of germination, the lag and growth rate of vegetative cells, and the time to toxicity.