No abstract

No abstract

SUMMARY– Thermal death‐time determinations in the temperature range of 165°F (73.9°C) to 185°F (85°C) were made of spores of five strains of Clostridium botulinum type E in tubed fish paste prepared from whole Great Lakes whitefish chubs. Estimated F176 (80°C) values for the destruction of approximately 1×106 spores per gram of fish paste were as follows: for strain Alaska, 34.2 min; Beluga, 17.0 min; 8E, 14.0 min; Iwanai, 12.5 min; and Tenno, 13.2 min. Estimated 95% confidence limits about these F176 values were for strain Alaska, 23.4‐49.5 min; Beluga, 14.2‐20.2 min; 8E, 8.2‐17.7 min; Iwanai, 10.2–15.4 min; and Tenno, 9.3–18.5 min. D176 values calculated from our F176 values by Schmidt's (1957) equation were for strain Alaska, 4.3 min; Beluga, 2.1 min; 8E, 1.8 min; Iwanai, 1.6 min; and Tenno, 1.6 min. Zy values obtained from thermal death‐time determinations were for strain Alaska, 13.2; Beluga, 13.3; 8E, 10.3; Iwanai, 13.6; and Tenno, 13.1°F.

Vibrio parahaemolyticus was isolated from soft-shell clams (Mya arenaria) taken from 10 different clamming areas on Cape Cod, Mass., during July and August 1972. Direct plating on thiosulfate-citrate-bile salts-sucrose agar was found to be superior to either direct plating on Vanderzant modified salt starch agar or enrichment with Trypticase soy broth containing 7% salt for isolation from clam samples. Morphological and biochemical characteristics of 33 isolates from 30 samples generally conform to those described for this organism in the literature, except for the production of acid from sucrose, lactose, and sorbitol. Six of the isolates were hemolytic on human blood agar plates, whereas all showed a negative Kanagawa phenomenon. Twenty of the 33 isolates reacted with pooled antisera to the K antigen; 15 of these reacted with 9 different specific K antisera, leaving 5 untypable. Ten of these 15 reacted with 4 different 0 antisera.

Nine strains of Vibrio parahaemolyticus from widely varied sources were exposed to heat in sterile clam homogenates. D-values were determined at temperatures ranging from 49 to 55 C for four strains, and at 51 C for the remaining five strains. The D-values in minutes, corrected for thermal lag and lethality during thermal lag, were 0.39 to 0.70 at 49 C. 0.26 to 0.54 at 51 C, 0.12 to 0.31 at 53 C, and 0.03 to 0.24 at 55 C. Values of z in degrees Centigrade determined for four strains were 5.6 to 12.4. One strain was found to be significantly more resistant at 53 and 55 C.