Microbiology Tech Info

  Aim To determine the ability of an organism to split amino acid tryptophan to Indole, which is important in the identification of Enterobacteriacea such as E.coli, Proteus vulgaris, P.rettgeri, Morganella morganii and Providencia sps., which have the capacity to produce indole. Principle Indole, a benzyl pyrrole, is one of the metabolic degradation products of the amino acid tryptophan. Bacteria that possess the enzyme tryptophanase are capable of hydrolyzing and deaminating tryptophan with the production of indole, pyruvic acid, and ammonia. Indole production is an important characteristic in the identification of many species of microorganisms, being particularly useful in separating Escherichia coli (positive) from members of the Klebsiella-Enterobacter-Hafnia-Serratia group (mostly negative). The indole test is based on the formation of a red complex when indole reacts with the aldehyde group of p-dimethylaminobenzaldehyde. This is the active chemical in Kovac’s and Ehr...