The method, in order to virulent, for the rattenbekaempfung certain salmonella - bacteria by storage in evacuated ampoules to make lagerfaehig

摘要

A rat exterminating compound containing desiccated, storable Salmonella bacteria in a virulent condition, is obtained by placing a suspension of the bacteria in a nutrient medium in an ampoule, drying in vacuo at room temperature, the pressure inside the ampoule being finally reduced to 2 mm. or less of mercury, and being maintained at this pressure during storage by sealing in vacuo. The nutrient medium is peptone bouillon containing 5 to 10 per cent gelatin. In the example, pressure in the ampoule is reduced to as low as 0.05 mm. mercury over 7 days, the pressure being reduced by approximately half each day. Each day fresh desiccant e.g. phosphorus pentoxide is placed in the vaccum vessel. In use, the ampoule is broken and its contents dispersed in a nutrient medium. Dispersion is facilitated by a strip of filter paper placed in the ampoule prior to sterilization and before the introduction of the bacterial suspension.