Physicochemical and microbiological analyses of bacterial isolates from drinking water distribution systems of some higher institutions in Edo State, Nigeria

Abstract

In drinking water systems, a large number of microorganisms live in complex communities in a selfproduced extracellular polymeric matrix associated with inner surfaces of pipes, walls and floors of storage tanks, joints and faucets. This study was aimed at analyzing the physicochemical and microbiological characteristics of bacterial isolates of drinking water distribution systems in some higher institutions in Edo State. The physicochemical parameters were determined by using standard protocol and microbiological water quality was conducted using the standard microbiological methods. The results of the physicochemical analysis showed that, the pH values ranged between 4.17 and 5.89. The highest (5.89) was recorded with samples from OK-R and the least (4.17) was obtained from UB-T. The electrical conductivity (EC) values for SA-R (104.8µS/cm), AA-R (105.5 µS/cm) and OKR (114.8 µS/cm) exceeded the permissible threshold value of 100µS/cm. Concentrations of lead for AA-R (0.02 mg/L) and OK-R (0.03 mg/L) were significantly higher than the acceptable level of 0.01mg/L. The mean total heterotrophic bacterial counts ranged from 3.3 ± 0.3 x 102 cfu/mL to 9.3 ± 0.3 x 102 cfu/mL, with the least and highest counts recorded for UB-R and AA-R. Phenotypically identified bacteria were the Citrobacter, Klebsiella, Bacillus, Pseudomonas, Proteus and Providencia species. The study revealed that drinking water system of biofilms is a reservoir for microorganisms that could cause public health concerns which is impacted by the presence of available nutrient, environmental conditions and heavy metals.

Keywords: biofilm, bacterial load, physicochemical, regression and level of significance.