Abstract

Development of biofilm in water storage tanks deteriorates the quality of drinking water in homes. The aim of this study was to identify bacteria that produce biofilm in water storage polyvinyl chloride tanks (WSPT). Water samples were obtained from WSPT of 70 households in Obio/Akpor and Port Harcourt Local Government Areas (OBALGA and PHALGA) in Rivers state, Nigeria. Samples were analyzed for total heterotrophic bacteria (THB), total and faecal coliform, Vibrio, and Salmonella/Shigella species which were screened for biofilm production using standard bacteriological procedures. Isolates positive for biofilm production were identified through conventional and molecular methods. THB count in samples from PHALGA and OBALGA ranged from 3.0±0.1×10⁴ to 1.04±0.01×10⁶ CFU/ml and 2.2±0.3×10⁴ to 2.30±0.03×10⁵ CFU/ml respectively; total coliform count ranged from 1.5±0.7×10 to 6.4±0.1×10² CFU/ml and 1.6±0.3×10² to 2.26±0.04×10³ CFU/ml respectively; faecal coliform count ranged from 0 to 1.6±0.3×10² CFU/ml and 8.0±0.0×10 to 1.54± 0.03×10³ CFU/ml respectively; Shigella count ranged from 5±0.0 x 10 to 1.1±0.1×10² CFU/ml and 8±0.1×10 to 3.5±0.1×10² CFU/ml while Salmonella counts ranged from 1±0.0 x10 to 4±0.01x10CFU/ml and 1±0.0 x10 to 9±0.1 CFU/ml for samples from PHALGA and OBALGA respectively. Ten genera among the bacterial isolates were positive for biofilm production and they include Proteus mirabilis LC728309, Shigella flexneri LR738991, Enterococcus faecium AB512765, Klebsiella aerogenes SGRCBNR5-D11, Serratia aquatilis NR_147771, Streptococcus algalactiae CP010867, Bacillus subtilis NR_102783, Enterobacter cloacae NR_102794, Alcaligens viscolactis AY911519, and Escherichia coli ETEC MF919609. The genera of Proteus, Shigella, Enterococcus, and Klebsiella were observed to be highest producers of biofilm. The presence of these bacteria particularly Escherichia coli ETEC MF919609 is worrisome and may constitute health hazard in water storage tanks. It is therefore recommended that the interior of WSPT should be cleaned regularly with a plan put in place to determine the frequency of cleaning.