Antibiotic Resistance Profiles and Hydrocarbon-Utilisation Potential of Indigenous Bacteria Isolated from Oil-Impacted Surface Waters of the Niger Delta, Nigeria

Oil contamination can alter microbial communities in aquatic environments, potentially favouring the coexistence of hydrocarbon- utilising bacteria and antibiotic-resistant organisms. This study investigated the antibiotic resistance pro iles and hydrocarbon- utilisation potential of indigenous bacteria isolated from oil-impacted surface waters at ive locations in the Niger Delta, Nigeria. Surface-water samples were analysed for selected physicochemical parameters and total petroleum hydrocarbons (TPH). Bacterial isolates were recovered and characterised using conventional microbiological methods, screened for hydrocarbon utilisation, and tested for susceptibility to eight antibiotics using the disc-diffusion method. The TPH-removal ef iciencies of selected isolates were also evaluated, and correlations among TPH concentrations, hydrocarbon-utilising bacteria and multidrug-resistant (MDR) isolates were examined. TPH concentrations ranged from 3.94 ± 0.27 mg/L at Bodo Creek to 8.21 ± 0.52 mg/L at Ataba Creek. Of the 87 bacterial isolates recovered, 38 (43.7%) demonstrated hydrocarbon-utilisation potential. The highest resistance rates were recorded against amoxicillin (81.6%) and ampicillin (76.3%), whereas resistance was lower against cipro loxacin (13.2%) and gentamicin (18.4%). Among the selected isolates, Pseudomonas aeruginosa achieved the highest TPH removal (70.8%), followed by Rhodococcus sp. (68.6%) and Acinetobacter sp. (65.8%), compared with 5.6% in the uninoculated control. Positive correlations were observed between TPH concentration and hydrocarbon-utilising bacteria (r = 0.81), TPH concentration and MDR isolates (r = 0.74), and hydrocarbon-utilising bacteria and MDR isolates (r = 0.69). These indings highlight the coexistence of hydrocarbon-utilising and antibiotic-resistant bacteria in oil-impacted waters, underscoring their potential value in bioremediation and the need for environmental monitoring to address associated public health concerns.