Botulinum Strains Research Articles

Survival of Clostridium botulinum Spores

Radiation survival curves of spores of Clostridium botulinum strain 33A exhibited an exponential reduction which accounted for most of the population, followed by a "tail" comprising a very small residual number [7 to 0.7 spore(s) per ml] which resisted death in the range between 3.0 and 9.0 Mrad dose levels. The "tail" was not caused by protective spore substances released into the suspensions during irradiation, by the presence of accumulated radiation "inactivated" spores, or by heat shock of pre-irradiated spores. The theoretical number of spore targets which must be inactivated by irradiation was estimated both by a graphical and by a computation method to be about 80, and the D value was calculated to be 0.295 and 0.396 Mrad, respectively, in buffer and in pork pea broth.

Pouch Method for the Isolation and Enumeration of Clostridia

An anaerobic film-pouch method has been developed for the isolation and enumeration of clostridia. Fabrication of the pouch is described. Counts of spore suspensions of Putrefactive Anaerobe 3679 and of Clostridium botulinum strains 41-B and 33-A in pouches were compared with those obtained by anaerobic-jar and agar-deep techniques. Statistical analysis revealed a significant difference in favor of the pouch over the tube and anaerobic-jar methods. Tests performed with C. welchii, both in spore suspension and added to chicken pot pie in culture form, also demonstrated the pouch to be at least as proficient as the other, more cumbersome, techniques.

Comparative resistance of strains of Clostridium botulinum to gamma rays.

A total of 102 strains of Clostridium botulinum (56 strains of type A, 43 type B, and 3 nontoxigenic strains which could not be typed) was examined for resistance to gamma rays. When these organisms were suspended in neutral phosphate buffer in concentrations of 10(4) spores per tube, the threshold sterilizing dose appeared to be 1.4 Mrad. Partial survival to 1.4 Mrad was shown by 10.7% of the type A strains, 18.6% of the type B strains, and one of three nontoxigenic strains. Over-all, type A strains indicated higher radioresistance than type B strains, although there was overlapping. Representatives of the most resistant strains had D values of 0.317 to 0.336 Mrad; the D values of an intermediate group were 0.224 to 0.253 Mrad, and the most sensitive strain studied, 51B, had a D value of 0.129 Mrad. The radioresistance of Putrefactive Anaerobe 3679, strain S-2, was comparable to the intermediate C. botulinum group (D = 0.209).

Radiation Survival Curves of Clostridium Botulinum Spores

SUMMARYSurvival curves were obtained for massive concentrations of spores of Clostridium botulinum strain 12885A, when subjected to a wide range of gamma radiation doses under various conditions. The spore concentrations ranged from 37,000 to 64,800,000,000 per ampoule, with no recovery at 5 Mrad or more. Only at lower doses were observed survival counts compatible with classical hit theory. More than one hit is apparently required to inactivate the Cl. botulinurn spore by gamma radiation. The number of hits required for inactivation is estimated at somewhere near 13. Freeze‐dried spores exhibited less radioresistance in the dry state than when resuspended in neutral phosphate buffer. Spore suspensions in neutral phosphate buffer exhibited less radioresistance when irradiated under air than when irradiated under nitrogen. Spores exhibited less radioresistance suspended in phosphate buffer than in a nutrient medium (pork‐pea infusion). Changes in concentration of spores over a range of 37 × 103 to 53 × 109 did not significantly affect the percent survival for a given dose except in the tail area. Regardless of spore concentration, a so‐called “tailing off” of surviving spores was observed at the higher dose levels employed for varying spore concentrations. The “tailing off” phenomenon did not appear to follow the classical hit theory.

Comparative Resistance of Strains of Clostridium botulinum to Gamma Rays1

A total of 102 strains of Clostridium botulinum (56 strains of type A, 43 type B, and 3 nontoxigenic strains which could not be typed) was examined for resistance to gamma rays. When these organisms were suspended in neutral phosphate buffer in concentrations of 10(4) spores per tube, the threshold sterilizing dose appeared to be 1.4 Mrad. Partial survival to 1.4 Mrad was shown by 10.7% of the type A strains, 18.6% of the type B strains, and one of three nontoxigenic strains. Over-all, type A strains indicated higher radioresistance than type B strains, although there was overlapping. Representatives of the most resistant strains had D values of 0.317 to 0.336 Mrad; the D values of an intermediate group were 0.224 to 0.253 Mrad, and the most sensitive strain studied, 51B, had a D value of 0.129 Mrad. The radioresistance of Putrefactive Anaerobe 3679, strain S-2, was comparable to the intermediate C. botulinum group (D = 0.209).

Radioresistance of Five Strains of Clostridium Botulinum in Selected Food Productsa,b

SUMMARYSpore recovery counts made on five strains of Clostridium botulinum indicated striking differences in radioresistance. Strain 12885A was most resistant, and strain 32B least resistant. A difference was noted in the survival of spores in five food products (green beans, chicken, codfish, pork, and beef), with green beans providing the most destruction. It was also observed that a given substrate was found to allow a greater per cent survival of one strain than another, so that two strains compared in one food do not always show the same relationship as when compared in another food. Some evidence indicates a modest recovery of viability of the irradiated spores during frozen storage prior to culturing. Since the character of the food determines in part the dose required for the destruction of Cl. botulinum, no single dose would be best for all food products.

Isolation and properties of a subtilin resistant strain of Clostridium botulinum.

Isolation and properties of a subtilin resistant strain of Clostridium botulinum.

A note on the heat resistance of a South African strain of Clostridium botulinum type B

AbstractThe z and D values for a South African strain of Clostridium botulinum, type B, have been determined by a method described. The results indicate that the South African strain at least equals in heat resistance the maximum resistance for Clostridium botulinum assumed in process calculations for canned foods.

Influence of Starch in Media Used for the Detection of Heated Bacterial Spores

DURING investigations of the heat resistance of the spores of several Australian strains of Clostridium botulinum, it was found that various agar media gave divergent estimates of spores surviving heat treatment, even though each medium indicated similar numbers of viable spores in the unheated suspension. An attempt was made, therefore, to prepare a medium which would be reliable for the detection or spores surviving heat treatment. It has now been shown that the addition of small amounts of starch to media increases the number of colonies which develop from an inoculum of heated spores. Several types of natural starches produce similar effects in different infusion media suitable for the growth of Cl. botulinum. The influence of different concentrations of soluble starch added to pork infusion thioglycollate agar1 is shown in the accompanying graph.

Differential Characters of Two Strains of Clostridium botulinum, Type E: Action of Toxins in Chickens.

SummaryDifferential characters of two strains of Clostridium botulinum, type E, are described. One strain was isolated from German-canned sprats; the other from Nova Scotian smoked salmon. Culturally they can be differentiated by colony formation on horse blood agar plates. Agglutination and absorption tests indicate them to be of distinct serologic groups.The toxins of both strains were neutralized reciprocally by their antitoxins. Tests for toxigenic activity demonstrated, however, that the toxins were not identical. Subcutaneous injections of both toxins uniformly gave rise to symptoms characteristic of botulism in guinea pigs, mice, rabbits, and kittens. White Leghorn chickens were highly susceptible to the toxin of the salmon strain but not to that of the sprat strain. In chickens 4 to 12 weeks old, approximately 6 to 8 guinea pig M.L.D. of the salmon toxin gave rise to fatal botulism, while doses of the sprat toxin several hundred times as large failed to kill or induce symptoms of botulism. The spr...

Growth-Stimulating Properties of Cystine and Tryptophan

It was reported in a previous study ia that the amino-acid tryptophan was apparently necessary to the growth of certain strains of Clostridium botulinum when the organisms were grown on mediums in which the only source of nitrogen was hydrolyzed casein and the preparations made from such hydrolysates. It was found that a medium prepared of hydrolyzed casein alone would not support growth but that when purified tryptophan was added in proportions sufficient to replace the original tryptophan of the casein, which had been destroyed during the course of acid (H2S04) hydrolysis, growth not only took place but was most profuse. It was later found, in a study lb of the growth of the same strains of bacteria on synthetic mediums, that tryptophan per se was not necessary to growth and that the organisms grew well in the complete absence of this amino-acid.

Growth of Clostridium Botulinum on Synthetic Mediums

The relationships of the amino-acids arginine, aspartic acid, glutamic acid, oxyglutamic acid and tryptophan to the growth of some strains of Clostridium botulinum were reported in a previous paper.1 The apparent intimate relationship existing between the presence of tryptophan and the growth of the organisms was suggestive and resulted in the development of a hypothesis, the essentials of which were formulated at that time