ISOLATION AND IDENTIFICATION OF COLIFORM BACTERIA AS AN INDICATOR OF MICROBIOLOGICAL QUALITY OF WATER

ABSTRACT

The study was carried out to isolate and identify coliform bacteria obtained from water samples in different locations or points. Nine samples were collected from Oredo LGA (Ekosodin, New Benin, and Uselu) and Ovia North-East LGA (BDPA, Isihor, Oluku, UNIBEN and Wasota). Physicochemical assessment was carried out for the samples while cultural methods were used for the determination of heterotrophic bacterial counts and biochemical properties. The phenotypic virulence determinants and antimicrobial susceptibility tests were also carried out using standard microbiological technique. The results revealed that the pH ranged from 6.06 - 7.59, while temperature (25.3 - 29.4 ^oC), electrical conductivity (13 – 159 µS/cm), turbidity (0.21 – 1.83 NTU), total suspended solid (0.23 – 0.98 mg/ml), Alkalinity (0.12 – 0.50), Hardness (1.05 – 2.95 mg/ml), Phosphate (0.1 – 1.99 mg/L), Nitrate (0.03 – 1.05 mg/L), and Sulphate (0.12 – 1.0 mg/L) were within acceptable range delineated by world health organization for drinking water.The bacteriological analysis of water samples showed that the heterotrophic bacterial count was found to range from 13.50±2.12 CFU/100ml to 81.00±4.24 CFU/100ml. The identified anaerobic bacterial isolates were Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens and Enterobacter cloacae. Bacillus (37.50%) and Escherichia (20.83%) were the most frequently occurring bacterial isolates from water samples in the study. The phenotypic virulence properties of the anaerobic bacterial isolates showed that they had at all virulence determinants evaluated in the study. The bacteria possessed hemolysin proteins as well as DNAse enzyme. The antibacterial sensitivity testing revealed that all isolatesfound wereall susceptible to Gentamicin and Ciprofloxacin but on the other hand were resistant to Metronidazole and Colistin. It was also evident that they were found to have an MAR index greater than 0.2 which means that the isolates were all pathogens of public health importance.