Ellners Broth

Principle And Interpretation

Ellners Broth is recommended (1, 2) for inducing sporulation in Clostridium perfringens. Spores are rarely seen in culture (a diagnostic feature) but can be obtained on Ellners Medium (1). In practice, the routine characterization of clostridia to species level involves morphological examinations, biochemical tests and identification of specific toxins. All clostridia produce spores but they vary markedly in their readiness to do so. Some of which may require prolonged incubation.

C. perfringens are gram-positive rods, often capsulated. In sugar-containing media, the Clostridium rods are shorter whereas in protein-containing media, they may become filamentous. Spores formed are usually in small numbers and are not formed in the presence of fermentable carbohydrates. Typically oval, sub-terminal or central spores are formed and are not bulging. Special media like Ellners Broth are used to produce spores.

Medium is composed of proteose peptone and yeast extract, which supply the necessary nutrients for the growth of the Clostridia. Generally sporulation is stimulated by an carbohydrate source and hence starch is included in the medium. Sulphate and phosphate not only buffer the medium but also help in sporulation. Clostridia are anaerobic organisms and hence anaerobiosis may be ensured by heating the medium at 100°C for 10 minutes and cooling just before inoculation. It is important that the inoculum should be adequate. 0.5 ml of an actively growing 4-12 hours Meat Broth culture should be introduced with a pipette into the bottom of the tubed medium and incubated anaerobically.