Coliform bacteria include organisms like Escherichia coli, Enterobacter,
Klebsiella and Citrobacter are gram negative, facultative anaerobic, non-sporulating and lactose
fermenting organisms. E.coli is used as the indicator organism for detection of fecal
contamination of water. Conventional methods for the detection of these Coliforms in water
include microbial culture assays in lactose containing media and also enzyme based assays for
the detection of β-galactosidase using chromogenic substrates like ortho-nitrophenyl-β-Dgalactopyranoside.
These methods are cumbersome with limited specificity. DNA based
molecular techniques like Polymerase chain reaction is recommended since it is highly specific.
In this paper, we report the use of PCR for the amplification of the Lac Z (β-galactosidase
encoding) gene to confirm the isolation of Coliform bacteria from drinking water samples. The
method could be an effective epidemiological tool to pin point the source to contain outbreaks of
waterborne disease episodes.