EFFECT OF PH AND NACL ON GROWTH FROM SPORES OF NONPROTEOLYTIC CLOSTRIDIUM-BOTULINUM AT CHILL TEMPERATURE

The effect of combinations of temperature (2 degrees, 3 degrees, 4 deg rees, 5 degrees, 8 degrees and 10 degrees C), pH (5.0-7.2) and NaCl (0 .1-5.0% w/w) on growth from spores of non-proteolytic Clostridium botu linum types B, E and F was determined using a strictly anaerobic mediu m. Inoculated media were observed weekly for turbidity, and tests were made for the presence of toxin in conditions that approached the limi ts of growth. Growth and toxin production were detected at 3 degrees C in 5 weeks, at 4 degrees C in 3/4 weeks and at 5 degrees C in 2/3 wee ks. The resulting data define growth/no growth boundaries with respect to low temperature, pH, NaCl and incubation time. This is important i n assessment of the risk of growth and toxin production by non-proteol ytic CI. botulinum in minimally processed chilled foods.