HYDROGEN SULPHID (H2S) PRODUCTION The detection of hydrogen sulphide gas (H2S) is used mainly to assist in the identification of enterobacteria and occasionally to differentiate other bacteria such as Bacteroides and Bruceila species. H2S is produced when sulphur – containing amino acids are decomposed.
Use of Kligler iron agar (KIA) to detect H2S This medium is suitable for detecting H2S production by enterobacteria. H2S is detected by the ferric citrate contained in the medium. Inoculate the test organism into KIA and incubate it at appropriate temperature over night. Observe blacking of the medium
Lead acetate paper test to detect H2S When a sensitive technique for detecting H2S production is required, the lead acetate paper test is recommended. Inoculate a tube or bottle of sterile peptone water or nutrient broth with the test organism. Insert a lead acetate paper strip in the neck of the bottle or tube above the medium, and stopper well. Incubate the inoculated medium at 35-37OC, and examine daily for a blackening of the lower part of the strip.