Purification and properties of an enterotoxin from a coatless spore mutant of Clostridium perfringens type A

Comparative Study of Enzyme Activity and Stability of Bovine and Human Plasmins in Electrophoretic Reagents, β-mercaptoethanol, DTT, SDS, Triton X-100, and Urea

Effects of common electrophoretic reagents, reducing agents (beta-mercaptoethanol [BME] and DTT), denaturants (SDS and urea), and non-ionic detergent (Triton X-100), on the activity and stability of bovine plasmin (b-pln) and human plasmin (h-pln) were compared. In the presence of 0.1% SDS (w/v), all reagents completely inhibited two plns, whereas SDS (1%) and urea (1 M) denatured plns recovered their activities after removal of SDS by treatment of 2.5% Triton X-100 (v/v). However, reducing agents (0.1 M of BME and DTT) treated plns did not restore their activities. Based on a fibrin zymogram gel, five (from b-pln) and four (from h-pln) active fragments were resolved. Two plns exhibited unusual stability in concentrated SDS and Triton X-100 (final 10%) and urea (final 6 M) solutions. Two bands, heavy chain-2 (HC-2) and cleaved heavy chain-2 (CHC-2), of b-pln were completely inhibited in 0.5% SDS or 3 M urea, whereas no significant difference was found in h-pln. Interestingly, 50 kDa (cleaved heavy chain-1, CHC-1) of b-pln and two fragments, 26 kDa (light chain, LC) and 29 kDa (microplasmin, MP), of h-pln were increased by SDS in a concentration dependent manner. We also found that the inhibition of SDS against both plns was reversible.

Effect of sporulation and recovery medium on the heat resistance and amount of injury of spores from spoilage bacilli

AIMS

To assess the influence of sporulation media on heat resistance, and the use of stress recovery media to measure preservation injury of spores of five representative spoilage bacilli.

METHODS AND RESULTS

Bacillus spores prepared on nutrient agar supplemented with Ca2+, Mg2+, Mn2+, Fe2+ and K+ were more heat-resistant than spores obtained from nutrient agar with Mn2+. This increased heat resistance correlated with a decrease in the protoplast water content as determined by buoyant density sedimentation. The degree of preservation injury severity could be assessed on media containing NaCl at moderate pH and organic acids at acid pH. Ca-DPA, K+ or proline were added to the recovery media to demonstrate that heat probably caused injury to both spore germination and the outgrowth system.

SIGNIFICANCE AND IMPACT OF THE STUDY

The metal content of sporulation media can strongly effect the validity of preservation resistance studies. The distinctive recovery media developed here can be relevant for assessing and comparing new preservation technologies.

Clostridium perfringens type A enterotoxin (CPE): more than just explosive diarrhea

The bacterial pathogen Clostridium perfringens is the most prolific toxin-producing species within the clostridial group. The toxins are responsible for a wide variety of human and veterinary diseases, many of which are lethal. C. perfringens type A strains are also associated with one of the most common forms of food-borne illness (FBI). The toxicosis results from the production and gastrointestinal absorption of a protein-enterotoxin known as CPE. The regulation, expression, and mechanism of action of CPE has been of considerable interest as the protein is unique. CPE expression is sporulation associated, although the mechanism of cpe-gene regulation is not fully elucidated. Cloning studies suggest the involvement of global regulators, but these have not been identified. Although very few type A strains are naturally enterotoxigenic, the cpe gene appears highly conserved. In FBI strains, cpe is chromosomally encoded; whereas in veterinary strains, cpe may be plasmid-encoded. Variation in cpe location suggests the involvement of transposable genetic element(s). CPE-like proteins are produced by some C. perfringens types C and D; and silent remnants of the cpe gene can be found in C. perfringens type E strains associated with the iota toxin gene. CPE has received attention for its biomedical importance. The toxin has been implicated in sudden infant death syndrome (SIDS) because of its superantigenic nature. CPE can destroy a wide variety of cell types both in vitro and in vivo, suggesting that it could have potential in the construction of immunotoxins to neoplastic cells. It is obvious that CPE is an interesting protein that deserves continued attention.

Molecular genetics and pathogenesis of Clostridium perfringens

Clostridium perfringens is the causative agent of a number of human diseases, such as gas gangrene and food poisoning, and many diseases of animals. Recently significant advances have been made in the development of C. perfringens genetics. Studies on bacteriocin plasmids and conjugative R plasmids have led to the cloning and analysis of many C. perfringens genes and the construction of shuttle plasmids. The relationship of antibiotic resistance genes to similar genes from other bacteria has been elucidated. A detailed physical map of the C. perfringens chromosome has been prepared, and numerous genes have been located on that map. Reproducible transformation methods for the introduction of plasmids into C. perfringens have been developed, and several genes coding for the production of extracellular toxins and enzymes have been cloned. Now that it is possible to freely move genetic information back and forth between C. perfringens and Escherichia coli, it will be possible to apply modern molecular methods to studies on the pathogenesis of C. perfringens infections.

The effect of a Clostridium perfringens 8-6 enterotoxin on viability and macromolecular synthesis in Vero cells

Clostridium perfringens type A 8-6 enterotoxin causes gross morphological damage to Vero cells grown in tissue culture. Damage was observed to occur after only 30 minutes exposure at concentrations as low as 20 ng/ml, and within 60 minutes 95% of the cells had detached. Concentrations as low as 0.01 ng were able to cause detectable inhibition of plating efficiency. The enterotoxin inhibited DNA, RNA and protein synthesis and caused the reversal of glucose transport. Heat inactivated enterotoxin had no effect on cell function or morphology.