Abstract

This study assessed the bioremediation efficiency of halotolerant Micrococcus luteus in crude oil-polluted water from Bonny, Rivers State, Nigeria. Eleven bacterial genera were isolated; Micrococcus sp., Pseudomonas sp., and Bacillus sp. showed strong halotolerance (growth at 10–40% NaCl) and hydrocarbon utilisation. Micrococcus luteus was selected for further study. A 90-day microcosm experiment was conducted using 3% (v/v) crude oil-contaminated water under four treatments: sterilised polluted water (control), unsterilised polluted water (natural attenuation), sterilised polluted water + M. luteus, and sterilised polluted water + M. luteus + NPK fertiliser. TPH was monitored by gas chromatography; microbial counts and physicochemical parameters were analysed periodically. The highest TPH degradation (77.0%) was recorded in the M. luteus + NPK treatment (TPH reduced from 8.992 mg/L to 2.065 mg/L), followed by M. luteus alone (39.3%), natural attenuation (25.0%), and sterile control (<5%). Nutrient amendment significantly increased microbial populations and accelerated hydrocarbon removal while reducing BOD, COD, TOC, and heavy metals. Halotolerant Micrococcus luteus, when augmented with NPK, offers a highly effective, eco-friendly approach for bioremediation of crude oil-contaminated saline environments.