Reduction of Sulphites by certain Bacteria in Media containing a Fermentable Carbohydrate and Metallic Salts

Abstract

(1) In media containing sodium sulphite, glucose, and iron salts, reduction of sulphite to sulphide is effected by B. typhosus, B. enteritidis (Gaertner), B. paratyphosus B, and various other members of the Salmonella group. No reduction was shown by B. paratyphosus A, and the various dysentery bacilli. (2) The use of certain media containing sodium sulphite is recommended in attempting to’ isolate typhoid and paratyphoid B bacilli from excreta, water, milk, etc. (3) It is suggested that the blackening which is brought about by certain members of the Typhoid-Paratyphoid-Enteritidis group in nutrient agar containing lead acetate is due, at least in part, to the reduction of sulphite im purities and that in order to get constant results with different brands of peptone an addition of sodium sulphite and a suitable fermentable carbo hydrate should be made to the medium.