Enumeration and genetic analysis of coliform bacteria from riverine systems of Rourkela: An index of water pollution

Abstract

The coliform group has been used extensively as an indicator of water quality and has historically leaded to the public health protection. The aim of this estimation is to examine methods currently in use or which can be proposed for the monitoring of Coliforms in drinking water. Purposely, the need for more rapid, sensitive and specific tests is required to know the bacterial population in domestic water. Most acceptable methods for coliform detection include the multiple-tube fermentation (MTF) technique and the membrane filter (MF) technique using different specific media and incubation conditions. These methods have some limitations, however, such as in the time of duration of incubation, antagonistic organism interference were observed. Nowadays, the simple and inexpensive membrane filter technique is the most widely used method for routine enumeration of Coliforms in domestic water water as wellas MF method is best suitable method to identify the coliform in domestic water area. The detection of Coliforms based on specific enzymatic activity have improved the sensitivity of these methods. The enzymes are beta-D galactosidase and beta-D glucuronidase are widely used for the detection and enumeration of total Coliforms and Escherichia coli, respectively. Many fluorogenic substrates exist for the specific detection of these enzymatic actions, and various profitable tests based on these substrates are available. Frequent comparisons have shown in these tests may be a suitable alternative to the conservative techniques. They are more expensive, and the incubation time, even though cheap, remains take too long time for same-day results. Detection of Coliforms by molecular methods is also proposed, as these methods allow for very specific and rapid detection without the need for a cultivation step. Molecular-based methods are evaluated here by the process by the polymerase chain reaction (PCR). In the immunological method, different antibodies against coliform bacteria have been formed, but the application of this technique often show low antibody specificity. PCR can be used to distinguish coliform bacteria by means of signal amplification. DNA sequence coding for the beta-galactosidase gene and the beta-D glucuronidase gene has been used to detect total Coliforms and E. coli respectively.