Triple iron sugar medium contains all, except ?
Ans. is d i.e., Maltose Triple sugar iron agar is used for the differentiation of microorganisms on the basis of :? Fermentation of dextrose (glucose), lactose and sucrose. Production of H2S. It is recommended for differentiation of enteric gram negative bacilli from clinical specimens, dairy samples and food products. Contents of the medium are :? Enzymatic digest of casein and animal tissue. Yeast enriched peptone. Three sugars : Dextrose (glucose), lactose and sucrose. Ferric ammonium citrate. Sodium chloride. Sodium thiosulfate. Phenol red. Agar. When carbohydrates are fermented, acid production is detected by the phenol red indicator, which is yellow in acid and red in alkaline conditions. Sodium thiosulfate is reduced to hydrogen sulfide (H2S) and H2S reacts with an iron salt yielding typical black iron sulfide. Ferric ammonium citrate is hydrogen sulfide indicator. Results Two areas of tube are examined : (i) Butt of the tube, and (ii) Slant of the tube. An alkaline slant (red)- acid butt (yellow) indicates fermentation of dextrose (glucose) only - red /yellow. Examples are Proteus mirabilis, salmonella thyphimurium and shigella flexneri. An acid slant (yellow) - acid butt (yellow) indicates fermentations of dextrose (glucose), lactose and/or sucrose - yellow/yellow. Example is E coli. An alkaline slant (red) - alkaline butt (red) indicates no fermentation (non-fermenter) - red/red. Example is Pseudomonas aeruginosa. An alkaline precipitate in butt indicates H2S production. It is produced by Proteus mirabilis and Salmonella typhimurium.
Lactose
Sucrose
Glucose
Maltose