Bacteriological analysis of water samples and the impact of seasonal variation on microbial load

Abstract

Water plays a significant role in the very existence of life in this universe. Globally, water related diseases present a major concern, to a large set of population. It thus becomes vital to check the quality of water that is being used either in domestic set up or for industrial purpose. In the present study, microbiological analysis of water sample collected from different locations such as River, Lake, Well and direct Rain water in and around Manipal, Karnataka were studied. The impact of seasonal variation on microbial load of these samples was also studied. The experimental design was carried out to estimate the number of microorganisms present and to characterise what type of organisms they are and the influence of varying seasons such as wet (monsoon) season and dry (summer) season on microbial load. Number of colonies was determined by total plate count method and growth characters and pattern were observed and noted down. Examination of motility of bacteria, Gram’s staining and different biochemical tests (IMViC) for bacteria were performed for different bacterial cultures and also the fungal staining was performed for the different fungal isolates obtained from the water samples. To check the quality of water for domestic and industrial use and to check for presence of faecal matter in water samples, the test for coliform bacteria through presumptive, confirmed and complete tests were performed. The results showed that all the water samples were safe for use as coliform organisms were not detected in the tested water samples, both in wet as well as well as dry season. The impact of seasonal variation that is the effect of dry and wet season on microbial load was also noted down. The various parameters that were examined to check for microbial load in varying seasons included difference in the number of colonies of microorganisms, their growth pattern and growth characters. From the tests conducted it was found that diverse and greater microbial load was observed in wet season compared to dry season.