Occurrence of fungal microbial contamination in drinking water of megacity of Karachi (Pakistan) and their physico-chemical control.

The water quality in Karachi (Pakistan) is uncertain due to the occurrence of fungi and other microorganisms. A total of twenty-five water samples were collected from public places, educational institutes, hospitals, water supply systems and surface water of the canal of Karachi (Pakistan). The different fungal species including Acremonium sp., Alternaria alternata, Aspergillus flavus, A. fumigatus , A. sulphureus, Cladosporium sp., Fusarium sp., Clonostachys (Gliocladium) sp., Macrophomina phaseolina , Mucor racemosus, Paecilomyces sp. Penicillium chrysogenum, P. citrinum, P. commune, P. expansum , Rhizoctonia sp. and Stachybotrys sp. were isolated from these drinking water samples. However, the bacteria, microalgae and some other microorganisms were present in low concentrations. The reason for fungi infection and production of mycotoxicity depends upon various factors and the availability of their nutrients in filtration plants. The major threats to human health are fungal mycotoxicity which is responsible for carcinogenic and other lethal diseases. Mostly, the genus Aspergillus was dominated and isolated with a maximum of 88-98% of occurrence in the different samples of drinking water by the direct plate-spread method. For the control of fungi, various Physico-chemical coagulation treatments were used, but Potassium alum, clay pot, and hot water treatment disinfected effectively 69-70% removal of the fungi and its spore or mycelia from the water. In addition, it is concluded that drinking water purifications such as chlorination, filtration and lime did not eliminate thermophilic fungal spores or mycelia including Penicillium , Paecilomyces and Mucor from the water.