Antimicrobial and Metal Tolerance of Bacteria Isolated from Underground Water Sample of Aged Crude Oil Contaminated Site

The study was aimed at evaluating metal tolerant and antibiotic resistant bacteria isolated from underground water around aged crude oil polluted site. Samples were collected from different locations around aged crude oil polluted site and control sample from an uncontaminated site of Bodo community, Gokana Local Government, Rivers state, Nigeria. The samples were cultured on nutrient agar, Bushnell Hass and MacConkay agar using standard microbial technique. Antibiogram of the isolated and identified bacteria were determined by Kirby-Bauer disc diffusion method. The bacterial tolerance of different concentrations of the heavy metals, Chromium, Vanadium, Arsenic, Cadmium and Lead was determined. The total heterotrophic bacterial count (THBC) of the samples ranged from 1.26×104 CFU/ml to 3.6×105 CFU/ml. Count of hydrocarbon utilizing bacteria (HUB) ranged from 1.02×103 to 3.2×103 CFU/ml and the coliform count of the sample ranged from 4.2×103 CFU/ml to 4.0×103ml. The predominant bacteria identified were Bacillus sp, Micrococcus sp, and Staphylococcus sp, Enterobacter sp and Proteus sp. All (100%) the Gram-positive bacteria were resistant to the antibiotic, Ceftazidime, Cefprozil and Cloxacin, 92% were resistant to Gentamycin and Erythromycin while 80% were resistant to Augmentin. All (100%) of the Gram-negative bacteria isolates were resistant to cefluroxime, 66% were resistant to Augmentin and Ceftazidim, and 33% were observed to be resistant to Nitrofurantin and Gentamicin. It was observed that all the isolates were tolerant to 50 µg/ml concentration, 70 to 100% of the isolates were tolerant to 100 µg/ml concentration, 17 to 100% were tolerant to 200 µg/ml concentration while 11 to 41% were tolerant to 300 µg/ml concentration of all the heavy metals studied. From this study, it was revealed that petroleum aged contamination could be a source of heavy-metal tolerance and antibiotic resistance in bacteria.