title: Egg-yolk trypticase soy agar for the enumeration of heat-damaged spores of Clostridium sporogenes.
abstract: In heat-resistance studies with spores of Clostridium sporogenes BC-2, an improved recovery medium was needed for severely heat-damaged spores as the used previously--Wynne medium in Miller-Prickett tubes--did not allow accurate counts of spores because of gas formation and disruption of agar. Initial test with pour plates of Viande-Leyure medium containing egg-yolk gave much increased counts for spores previously heated for 50 min at 112 degrees C; this increase was attributed to the presence of egg-yolk. Addition of egg-yolk to Reinforced Clostridial Agar, All-Culture Medium and Trypticase Soy Agar showed that Trypticase Soy Agar with egg-yolk was the best recovery medium. For the final formulation, the value of supplementation with cysteine-HCl and methylene blue was also shown. The resultant Egg-yolk Trypticase Soy Agar is conveniently prepared from BBL Trypticase Soy Agar (40 g) with the addition of 0.4 g/l cysteine-HCl, 4 mg/l of methylene blue and 2% Oxoid egg-yolk emulsion aseptically to the melted basal medium. For optimal spore counts, pour plates are incubated anaerobically for 5--7 d at 30 degrees C.
mesh_terms: D002364:Caseins; D003013:Clostridium / Q000302:isolation & purification / Q000502:physiology*; D003470:Culture Media; D004530:Egg Yolk; D005260:Female; D006358:Hot Temperature; D011492:Protein Hydrolysates; D013171:Spores, Bacterial / Q000302:isolation & purification / Q000502:physiology
chemical_list: D002364:Caseins; D003470:Culture Media; D011492:Protein Hydrolysates; C026375:trypticase-soy broth