Identification and characterization of chlorine-resistant bacteria from water distribution sites of Mumbai.

Chlorination is the oldest and widely practiced method for disinfection of potable water across the globe but some microorganisms survive the chlorine treatment and become resistant. In this study, chlorine-resistant bacteria were isolated from 36 reservoirs of the Municipal Corporation of Greater Mumbai. Water was collected in winter, summer and rainy season. The 8 isolates (out of 89) found to be resistant to 20 ppm of chlorine were identified and belong to the Acinetobacter and Serratia sp. The antibiotic resistance profile showed that the isolates were resistant to a broad spectrum of antibiotics which is of concern. Biofilm production was also observed in most of the isolates. Presence of chlorine-resistant bacteria in drinking water is an alarming situation which needs further analysis especially to understand the further characteristics of these isolates for their antibiotic resistance.