Practical Media and Control Measures for Producing Highly Toxic Cultures ofClostridium botulinum, Type A

Abstract

mately 0.1 ml of the turbid supematant fluid from a well-stirred meat mash stock culture to a tube or bottle containing a medium similar to those being tested. After incubation at 34 C for 18 to 30 hours appropriate aliquots were transferred aseptically to experimental media. Initially inocula were sometimes taken directly from meat mash cultures to test media; however, this introduced the possibility of carrying over unknown ingredients which would influence the results. Final data were obtained with inocula from cultures which had undergone several serial transfers in appropriate liquid media at 24to 48-hour intervals. The corn steep liquor employed in many experiments was obtained in wooden barrels from the Corn Products Refining Company, Argo, Illinois. As received, it contained approximately 50 to 60 per cent solids. When media containing this material were sterilized in the autoclave, massive precipitates were encountered. To avoid this difficulty the corn steep liquor was diluted sufficiently with water to make a thin, free-flowing slurry, which-was then adjusted to pH 8.4 to 9.0 with concentrated sodium hydroxide. The mixture was heated to boiling and clarified by centrifugation or filtration. Approximately 40 per cent of the solids were removed. The filtrate could then be incorporated in culture media with the formation of relatively little precipitate upon sterilization. The quantities of com steep liquor used in this investigation have been recorded in terms of the approximate amounts of total solids.

Recombination and insertion events involving the botulinum neurotoxin complex genes in Clostridium botulinum types A, B, E and F and Clostridium butyricumtype E strains

“…The history of the three strains is not clear, however, they appear to be different strains isolated from foodborne outbreaks of botulism [ 15 ]. The serotype A Hall strain is distinctive in that it produces a high concentration of toxin in culture [ 16 ]. Unique to the ATCC 3502 strain is the presence of a 16 kb plasmid [ 17 ].…”

Regulation of neurotoxin and protease formation in Clostridium botulinum Okra B and Hall A by arginine

“…It is likely that competition for nutrients also affects colonization and may influence toxin production. Several investigators have shown that supplementation of complex media with certain nutrients, e.g., meat or casein digests, glucose, or tryptophan, increases the synthesis of toxin (4,5,12,16). In complex media, however, it is difficult to accurately assess the effects of specific nutrients on the expression of toxin or the pathways of nutrient utilization (2).…”

Toxin production by Clostridium botulinum type A under various fermentation conditions

“…Discrepancies between the data obtained with static cultures and with the fermentor may be due to difficulties in obtaining representative samples with static cultures. Mixing of static cultures in preparation for sampling may introduce sufficient oxygen to inhibit the growth of C. botulinum (3,10). In addition, variations in toxin production may be attributed to differences in medium composition.…”