Isolation, purification, characterization, and physiological behavior of drinking water-borne pathogenic bacteria.

Abstract

The present work was devoted for isolation, characterization, and studying physiological behavior of drinking water borne pathogenic bacteria isolated from tap and cooling water. Total of 171 bacterial isolates were isolated from twenty nine different localities on eight common and specific agar media (Nutrient, Salmonella & Shigella, Desoxycholate citrate, Eosin–methylene blue, Thioglycollate, Mannitol salt, MacConkey and Clostridium) agar media. All bacterial isolates were purified and characterized on the basis of morphological, physiological, and biochemical tests. These lead to the following suggested names: Bacillus cereus (8); B. badius (1); B. macerans (1); B. brevis (6); B. circulans (4); B. coagulans (3); B. firmus (4); B. globisporus (2); B. megaterium (10); B. mycoides (3); B. pantotheniticus (9); B .pasteurii (1); B. pumilus (1); Staphylococcus gallinarum (1); Staph. epidermidis (6); Staph. haemolyticus (1); Staph. sciuri (2); Enterobacter aerogenes (1); Micrococcus halobius (2); M. sedentarius (1); M. varians (1); Pseudomonas aeruginosa (6); Klebsiella oxytoca (2); K. pneumonia (3); Enterobacter agglomerans (3); Edwardsiella ictalluri (4); Citrobacter freundii (1); Salmonella typhi (3); S. pullorum (1); Shigella dysenteriae (2); Sh. flexneri (2); Proteus mirabilis (13); Providencia stuartii (1); Pro. Rettgeri (2); Proteus rettgeri (1) and Escherichia coli (2).Thirty six characterized bacterial strains were selected and studying some physiological characteristics and evaluating of their five extracellular enzymes potencies including α-amylase, cellulase, lipase, pectinase, and protease with percentage of 41.66, 41.66, 33.33, 11.11, & 94.44 % respectively among all selected bacterial strains. The selected water borne pathogenic bacterial strains were growing at different pH values covering a relatively wide range of pH (4-12). Minimum, maximum, and optimum pH values for their growth were determined as 4, 12, and 7 respectively. Selected isolates showed abundant growth within the temperature range of 10-55ºC. Bacterial strains succeeded to grow in sodium chloride free medium and also containing sodium chloride up to 12.5 % (w/v). Recorded data emphasized that tested drinking water samples were polluted with different waterborne pathogenic bacteria and by investigating its physiological behavior, the virulence of the 36 bacterial strains was controllable.

New Egyptian Journal of Microbiology Vol. 17 (2) 2007: pp. 105-120