MICROBIOLOGY AND WATER QUALITY ASSESSMENT OF THE LOWER GANGETIC PLAINS, BANGLADESH

Ganges River Delta aquifers are of utmost concern due to contamination from elements (like arsenic) and pathogens. After millions of cases of chronic arsenic poisoning in the region, many lower Gangetic plains residents have resorted to drinking water from shallow to intermediate depth wells to reduce the threat of arsenic leaching into water from surrounding sediments. The increasing incidence of gastroenteritis indicates the need for bacterial pathogen (i.e. Salmonella) and non-pathogen (i.e. Enterobacteriaceae) prevalence at locations and depths that provide easy access to drinking waters. Present study sampling locations are along piezometer nests and every nest contains samples from wells at differing depths.

Seventeen water samples were enriched in buffered peptone water and incubated at 37^oC for 18 hours. Bacterial DNA was extracted and amplified using a qPCR machine. Amplification plots were analyzed to determine presence/absence of the microorganism. All water samples (n=~42) will be analyzed for Salmonella, Escherichia coli O157:H7, Listeria spp. and Shigella. Pathogen populations of PCR-positive water samples will be enumerated using the agar direct plate method. Non-pathogenic bacterial indicator organisms (i.e. Enterobacteriaceae) will also be enumerated. Over the course of the experiment, we hypothesize that shallower wells will 1)have a higher pathogen prevalence and 2)harbor pathogens at higher concentrations. While the samples analyzed to date (n=17) were all negative for Salmonella, we anticipate subsequent sample analyses may reveal pathogenic contamination due to livestock and anthropogenic wastes in the area. With farmers using shallow depth aquifers to irrigate crops, the risk to public health is great.