5 Jan 2012

HYDROGEN SULPHIDE PRODUCTION


HYDROGEN SULPHIDE PRODUCTION
The detection of hydrogen sulphide gas is used mainly to assist in the identification of enterobacteria and occasionally to differentiate other bacteria such as Bacteroides and Brucella species. Hydrogen sulphide is produced when sulphur containing amino acids are decomposed.The technique used to detect the release of hydrogen sulphide gas must not be too sensitive other wise it will detect the small places of hydrogen sulphide produced by most enterobacteria.


USE OF KLIGLER IRON AGAR (KIA) TO DETECT HYDROGEN SULPHIDE
This medium is suitable for detecting H2S production by enterobacteria.H2S is detected by the ferric citrate contained in the medium.

LEAD ACETATE PAPER TO DETECT HYDROGEN SULPHIDE
When a sensitive technique for detecting H2S production is required,the lead acetate paper test is recommended.
1.         Inoculate a tube or bottle of sterile peptone water or nutrient broth with the test organism.
2.         Insert a lead acetate paper strip in the neck of the bottle tube above the medium and stopper well.
3.         Incubate the inoculated medium at 35-37oC and examine daily for a blackening of the lower part of the strip.

RESULTS:

Blackening……………………………Positive test (H2S produced)

No blackening………………………. Negative test (No H2S is produced)


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