Sporulation and enterotoxin production by Clostridium perfringens type A under conditions of controlled pH and temperature

Inhibition of Clostridium perfringens sporulation by Bacteroides fragilis and short-chain fatty acids

The effect a common fecal organism, Bacteroides fragilis, has on the sporulation of Clostridium perfringens, an organism linked to some cases of antibiotic associated diarrhea, was examined. Established B. fragilis cultures significantly decreased the number of heat resistant spores formed by C. perfringens ATCC 12915 and increased the number of vegetative cells. To determine if short-chain fatty acids (SCFA), fermentation products of B. fragilis, inhibited sporulation, the SCFA were added to sporulation broth. Sporulation decreased in the presence of acetate, isobutyrate, isovalerate, and succinate. Vegetative cell number for C. perfringens decreased in the cultures with isobutyrate. Propionate did not affect sporulation or vegetative cell number. The data support the hypothesis that the decrease in short-chain fatty acid concentration following antibiotic therapy predisposes patients to diarrheas caused by C. perfringens.

A comparative study on the conditions of growth and sporulation of three strains of Clostridium perfringens type A

Different conditions of growth and sporulation of a strain of Clostridium perfringens type A (NCTC 8798) and two derived mutant strains, the lysozyme-germination dependent strain 8-6 and the revertant strain R3, have been determined. No sporulation was detected for the three strains in the Duncan and Strong (DS) medium; 100% sporulation was routinely obtained for the two mutant strains in the defined (D) medium. Factors promoting in vitro sporulation of C. perfringens type A were assayed: the volume of the culture, the type of preculture, and the addition of lysozyme in precultures. The paper also provided additional information on growth and sporulation of the mutant strains 8-6 and R3. Glucose concentrations up to 11 mM produced high percentages of sporulation. However, strain R3 still sporulated at 20% with 56 mM of glucose. A high volume of D medium led to slow growth kinetics and favoured sporulation. Faster kinetics of growth and the best percentage of sporulation were obtained with a young inoculum of the two mutant strains. On the other hand, the type of medium in the precculture (fluid thioglycollate (FTG) or basal carbonate yeast trypticase (BCYT)) did not influence the percentage of sporulation. However, while strain R3 was not affected by the addition of lysozyme in D medium, kinetics of growth were strongly influenced by this addition in strain 8-6, and the percentage of sporulation increased with a preculture in FTG medium and decreased when BCYT medium was used.

Sporulation and enterotoxin production by Clostridium perfringens type A at 37 and 43 degrees C

Enterotoxin-positive strains of Clostridium perfringens were grown in Duncan-Strong sporulation medium in the presence of 0.4% (7.9 mM) raffinose at 37 and 43 degrees C. Enterotoxin- and heat-resistant spores were produced at similar concentrations but sooner at 43 degrees C than at 37 degrees C. There was a direct relationship between spore heat resistance and sporulation temperature (32, 37, and 43 degrees C).

Influence of elevated temperature on starch hydrolysis by enterotoxin-positive and enterotoxin-negative strains of Clostridium perfringens type A

Enterotoxin-positive (Ent+) and enterotoxin-negative (Ent-) strains of Clostridium perfringens were cultured in Duncan-Strong sporulation medium containing starch at 37 and 46 degrees C. At 37 degrees C, all strains degraded starch and sporulated well. However, only Ent- strains could hydrolyze starch, grow extensively, and sporulate at 46 degrees C. Growth, sporulation, and starch hydrolysis by Ent+ strains at 46 degrees C were equivalent to those obtained at 37 degrees C when alpha-amylase was added to the cultures during growth. The total amount of extracellular plus intracellular amylase in cultures of Ent+ strains was significantly less in cells incubated at 46 degrees C than in cells incubated at 37 degrees C. These results contradict an earlier report that Ent+ strains cannot sporulate well near their optimal growth temperature (R. G. Labbe and C. L. Duncan, Can. J. Microbiol. 20:1493-1501, 1974) and suggest that synthesis of alpha-amylase in Ent+ strains is regulated by temperature.

Enterotoxin synthesis by nonsporulating cultures of Clostridium perfringens

Chemostat-cultured Clostridium perfringens ATCC 3624 and NCTC 10240, and a nonsporulating mutant strain, 8-5, produced enterotoxin in the absence of sporulation when cultured in a chemically defined medium at a 0.084-h-1 dilution rate at 37 degrees C. The enterotoxin was detected by serological and biological assays. Examination of the chemostat cultures by electron microscopy did not reveal sporulation at any stage. The culture maintained enterotoxigenicity throughout cultivation in a continuous system. The enterotoxin was detected in batch cultures of each strain cultivated in fluid thioglycolate medium and a chemically defined medium. No heat-resistant or light-refractile spores were detected in batch cultures during the exponential growth.

Relationship of sporulation, enterotoxin formation, and spoilage during growth of Clostridium perfringens type A in cooked chicken

Sporulation and enterotoxin formation were determined for 17 strains of Clostridium perfringens type A in autoclaved chicken dark meat and in Duncan-Strong sporulation medium. The mean numbers of heat-resistant spores detected after 24 h at 37 degrees C were log10 1.13 to log10 7.64/ml in Duncan-Strong medium and log10 4.93 to log10 6.59/g in chicken. Of 17 strains, 7 formed enterotoxin in Duncan-Strong culture supernatant (1.0 to 60 microgram/ml) and 8 produced enterotoxin in chicken (0.21 to 24 microgram/g). Additional studies with chicken were conducted with C. perfringens NCTC 8239. With an inoculum of 10(6) cells per g, greater than log10 7.99 vegetative cells per g were detected by 4 h in chicken at 37 degrees C. Heat-resistant spores occurred by 4 and 6 h and enterotoxin occurred by 8 and 6 h in autoclaved chicken dark meat and barbecued chicken drumsticks, respectively. Enterotoxin was detected in autoclaved dark meat after incubation at 45 degrees C for 1.5 h followed by 37 degrees C for 4.5 h, but not after incubation at 45 degrees C for 1.5 to 8 h. With an inoculum of 10(2) cells per g in oven-cooked or autoclaved chicken, greater than log10 8.00 vegetative cells per g were detected by 6 to 8 h at 37 degrees C, heat-resistant spores were detected by 8 h, and enterotoxin was detected by 12 h. A statistical analysis of odor determinants of chicken after growth of C. perfringens indicated that, at the 95% confidence level, the product was considered spoiled (off or unwholesome odor) by the time spores or enterotoxin were formed.

Effects of pH shifts, bile salts, and glucose on sporulation of Clostridium perfringens NCTC 8798

The sporulation of Clostridium perfringens NCTC 8798 was studied after exposing vegetative cells to: pH values of 1.5 to 8.0 in fluid thioglycolate broth (for 2h) and then transferring them to Duncan-Strong (DS) sporulation medium; sodium cholate or sodium deoxycholate (0.3 to 6.5 mM) in DS medium; or Rhia-Solberg medium with 0.4% (wt/wt) starch, glucose, or both added at 0 to 55 mM. At pH 1.5, no culturable heat-resistant spores were formed. For cells exposed to pH 3.0, 4.0, 5.0, or 6.0, increases in heat-resistant spores were not seen until after a lag of 12 to 13 h, whereas the lag was only 2 to 3 h for cells exposed to pH 7.0 or 8.0. Maximal spore crops were produced after only 6 to 8 h for cells exposed to pH 7 or 8, but 16 to 18 h was required for production of maximal spore crops by cells exposed to the lower-pH media. The addition of sodium cholate (3.5 to 6.5 mM) to DS medium only slightly reduced the culturable heat-resistant spore count from 1.9 X 10(7) to 3 X 10(6)/ml. The addition of 1.8 mM or more sodium deoxycholate reduced the culturable heat-resistant spore count to less than 10/ ml. When either starch or glucose alone was added to Rhia-Solberg medium there was no production of culturable heat-resistant spores, but a combination of 0.4% (wt/wt) starch and 4.4 mM glucose yielded 6 X 10(5) spores/ml. The spore production remained at this level for glucose concentrations of 6 to 22 mM, but then declined to about 3 X 10(3) spores per ml at higher concentrations.

Effect of carbohydrates and control of culture pH on beta toxin production by Clostridium perfringens type C

Clostridium perfringens type C strain CN 5384 produced a higher level of beta toxin in a controlled pH medium containing 1% glucose, starch, or sucrose than in media with dextrin, fructose, or raffinose. Toxin synthesis was not related to the growth yield. The effect of glucose on beta toxin production by 11 strains was investigated with and without control of the culture pH at 7.5. Strain CN 5386 produced distinctly higher toxin when the pH of the culture was maintained at 7.5, compared with uncontrolled pH.

Spore coat protein and enterotoxin synthesis in Clostridium perfringens

Polyacrylamide gel profiles of Clostridium perfringens spore coat protein revealed four and occasionally five components. Pulse-chase experiments indicated that synthesis of coat protein polypeptide and enterotoxin was an early sporulation event. However, maximum synthesis occurred coincident with the onset of heat resistance.

Evidence for stable messenger ribonucleic acid during sporulation and enterotoxin synthesis by Clostridium perfringens type A

Stable messenger ribonucleic acid (mRNA) was shown to be involved in both enterotoxin synthesis and synthesis of other spore coat proteins in Clostridium perfringens. When used at a concentration that inhibited [14C]uracil incorporation, rifampin, a specific inhibitor of deoxyribonucleic acid-dependent RNA polymerase, prevented incorporation of a mixture of labeled amnoo acids by 3-h sporulating cells. At that time, enterotoxin protein was first detectable and cells were primarily at stage II or III of sporulation. When rifampin or streptolydigin was added to 5-h sporulating cells, which were primarily at stage IV or V and had significant toxin levels, incorporation of labeled amino acids continued through 30 min despite its presence. Rifampin also failed to prevent the specific synthesis of enterotoxin, a structural protein of the spore coat. The half-life of enterotoxin RNA was estimated to be at least 58 min. When cell extracts from 5-h sporulating cells that had been exposed to 3H-labeled amino acids for 10 min were subjected to electrophoresis on polyacrylamide gels and the gels were subsequently analyzed for radioactivity, two major peaks of radioactivity were obtained. The two peaks corresponded to enterotoxin and another spore coat protein(s). Similar results were obtained when the cells had been preincubated for 60 min with rifampin before label addition, indicating the functioning of stable mRNA.

Synthesis of deoxyribonucleic acid, ribonucleic acid, and protein during sporulation of Clostridium perfringens

The kinetics of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein synthesis as well as protein breakdown during sporulation by Clostridium perfringens were determined. Maximum levels of DNA and net RNA synthesis occurred 3 and 2 h, respectively, after inoculation of sporulation medium. The rate of RNA synthesis decreased as sporulation progressed. Deoxyadenosine increased uptake of [14C]uracil and [14C]thymine but depressed the level of sporulation and the formation of heat-resistant spores when added at concentrations above 100 mug/ml. Unlike Bacillus species, net protein synthesis, which was sensitive to chloramphenicol inhibition, continued during sporulation. The rate of protein breakdown during vegetative growth was 1%/h. During sporulation this rate increased to 4.7%/h. When added to sporulation medium at 0 time chloramphenicol reduced protein breakdown to 1%/h. If added at 3 h the rate decreased to 2.1%/h. The role of proteases in this process is discussed.

Experimental diarrhea in cynomolgus monkeys by oral administration with Clostridium perfringens type A viable cells or enterotoxin

Purified C. perfringens type A enterotoxin fed orally in an amount of 5 mg caused both vomiting and diarrhea in the monkey only when the gastric juice had been neutralized. Exposure of enterotoxin to pH 4.0 or below rapidly destroyed the activity. All three monkeys receiving sodium bicarbonate and 2.4 X 10(10) viable cells grown in DS medium developed diarrhea, and only one of them vomited once. The diarrhea lasted for 13, 18 and 19 hr. The symptoms were similar to those reported in human cases of C. perfringens food poisoning. These results have verified the general notion that C. perfringens food poisoning should be categorized as a true "intravital intoxication". The reversed passive hemagglutination test detected enterotoxin directly in most fecal samples. This method may be applicable for diagnosis of human cases of C. perfringens food poisoning. Neither enterotoxin nor anti-enterotoxin was detected in serum samples taken from any monkey up to 21 days after the challenge. We are tempted to conclude, therefore, that no significant amount of C. perfringens enterotoxin is absorbed from the intestine.