Toxicity of Soot Against Microorganisms Isolated from Artisanal Crude Oil Refining Sites in the Niger Delta

Background and Objective: Soot is a mass of impure carbon, considered to be an airborne contaminant in areas where artisanal crude oil refining takes place.This study aimed to isolate microorganisms from soot-contaminated plants, water and soil samples within the vicinity of artisanal crude oil operations in Tombia Kingdom, Rivers State, Nigeria.Materials and Methods: Isolates were identified using molecular technique, by comparing their 16S rRNA and ITS genes with previously identified microorganisms in the NCBI data.A biotoxicity assay was conducted to determine the effect of different concentrations (1,10,100, 1000 mg/L) of soot against selected isolates.Microbial growth was monitored for 24, 48, 72 and 96 hrs.Results: Mean concentrations of the heavy metals in soot ranged from 1.29±1.80-25.09±32.51mg/kg during the wet season and from 8.52±0.20-80.51±0.61mg/kg during the dry season.The isolates used for the biotoxicity assay closely matched with six bacteria, Enterobacter asburiae (61.6%),Pantoea dispersa (100%), Kocuria rhizophila (98%), Bacillus cereus (98.8%),Bacillus subtilis (100%), Enterobacter bugandensis (100%) and one fungus Exophiala dermatitidis (100%).All isolates were able to grow in the presence of high concentrations of soot, for 96 hrs.Conclusion: Functional genes for hydrocarbon degradation (alkB and PAH) were detected in some of the isolates.The isolates showed tolerance to soot and could be useful in bioremediation of polluted soil.