LYSINE LACTOSE BROTH

The family Enterobacteriaceae consists of gram-negative facultative anaerobic non-spore forming bacteria. These grow well on peptone meat extract media. However, several other factors have influenced the development of media for detection, isolation and enumeration of members of the Enterobacteriaceae. Decarboxylases are the enzymes that remove a molecule of CO2 from an amino acid to form alkaline-reacting amines. Cadaverine is the amine degradation product of lysine. Many non-fermenters display only weak decarboxylase activity and many produce insufficient amines to convert the pH indicator system. This can be overcome by using only small quantities of substrates and heavy inoculum of pre-grown organisms in which a high concentration of enzymes has already accumulated. Overlaying the culture medium with 4 mm of petrolatum increases the sensitivity of detection. The initial conversion of the medium to a yellow colour, as acids accumulate from small amounts of glucose in the medium, is seen in case of the fermenters but not with the non-fermenters. The end point reactions are read comparing the strong alkaline purple colour reactions with the lighter bluish purple hue of the controls. Tubes should be incubated at 35?C for upto 5 days before interpreting the reactions as negative. Falkow formulated Lysine Broth (It is also named as Falkow Lysine Broth) for detection of lysine decarboxylase by means of a colour reaction in enteric bacilli.

for determination of lysine decarboxylase activity of lactose nonfermenting members of Enterobacteriaceae especially Salmonellae

Escherichia coli | Proteus vulgaris | Salmonella Enteritidis | Salmonella Typhimurium | Serratia marcescens

Food & Beverages | Veterinary

500 gm