Occurrence of coliforms and biofilm-forming bacteria in raw, treated, and distributed water from two waterwork systems in Osun State, Southwestern Nigeria

Abstract

This study assessed the bacteriological quality of raw, treated, and distributed water from Ede-Erinle and Opa reservoirs in Osun State, Nigeria. This was to determine the potability of water from these waterwork stations. Eighteen sampling points were established across the two reservoir networks for this study. Samples were collected bi-monthly for two annual cycles. Serial dilution and pour plate methods were employed for the enumeration of bacterial load. Total heterotrophic bacteria count (THBC) and total coliform bacteria count (TCBC) were enumerated on nutrient and MacConkey agar at 37 °C, respectively. Bacterial isolates were characterized using biochemical identification methods with reference to Bergey's Manual of Determinative Bacteriology. Bacterial isolates and biofilm formation were further identified molecularly through the PCR method using specific universal primers. Mean values of THBC and TCBC in distributed water from Ede-Erinle (9.61 × 104 ± 1.50 × 104 CFU/mL; 69.56 ± 26.81 CFU/mL) and Opa waterworks (9.58 × 104 ± 2.55 × 104 CFU/mL; 142.94 ± 44.41 CFU/mL) exceeded permissible limits for drinking water. Paenibacillus lautus, Bacillus pseudomycoides, Pseudomonas aeruginosa, and Pseudomonas stutzeri showed biofilm-forming capacity. The study concluded that the presence of coliforms and biofilm-forming bacteria in distributed water implies that the water is unfit for consumption without further treatment. HIGHLIGHTS Molecular identification of coliforms from the two reservoirs and their channels.; Molecular detection of biofilm bacteria in water from the two waterwork systems.; Comparison of molecular loads of water from the two waterwork systems.; Health implications of the identified bacteria from the two waterwork systems.; Potablilty of water from the two reservoirs and their stations.;

Keywords

• biofilm-forming bacteria
• coliforms
• reservoir
• waterworks systems