Dynamics of indigenous bacterial communities associated with crude oil degradation in soil microcosms during nutrient-enhanced bioremediation

Abstract

Bacterial population dynamics were examined during bioremediation of an African soil contaminated with Arabian light crude oil and nutrient enrichment (biostimulation). Polymerase chain reaction followed by denaturing gradient gel electrophoresis (DGGE) were used to generate bacterial community fingerprints of the different treatments employing the 16S ribosomal ribonucleic acid (rRNA) gene as molecular marker. The DGGE patterns of the nutrient-amended soils indicated the presence of distinguishable bands corresponding to the oil-contaminated-nutrient-enriched soils, which were not present in the oil-contaminated and pristine control soils. Further characterization of the dominant DGGE bands after excision, reamplification and sequencing revealed that Corynebacterium spp., Dietzia spp., Rhodococcus erythropolis sp., Nocardioides sp., Low G+C (guanine plus cytosine) Gram positive bacterial clones and several uncultured bacterial clones were the dominant bacterial groups after biostimulation. Prominent Corynebacterium sp. IC10 sequence was detected across all nutrient-amended soils but not in oil-contaminated control soil. Total heterotrophic and hydrocarbon utilizing bacterial counts increased significantly in the nutrient-amended soils 2 weeks post contamination whereas oil-contaminated and pristine control soils remained fairly stable throughout the experimental period. Gas chromatographic analysis of residual hydrocarbons in biostimulated soils showed marked attenuation of contaminants starting from the second to the sixth week after contamination whereas no significant reduction in hydrocarbon peaks were seen in the oil-contaminated control soil throughout the 6-week experimental period. Results obtained indicated that nutrient amendment of oil-contaminated soil selected and enriched the bacterial communities mainly of the Actinobacteria phylogenetic group capable of surviving in toxic contamination with concomitant biodegradation of the hydrocarbons. The present study therefore demonstrated that the soil investigated harbours hydrocarbon-degrading bacterial populations which can be biostimulated to achieve effective bioremediation of oil-contaminated soil.

Spatial variations of hydrocarbon contamination and soil properties in oil exploring fields across China

“…Microbial population number is one of important biological indicators in oil contaminated sites since microbes play an important role in contaminants degradation [38,39]. Microbial populations of heterotrophic bacteria in the seven oil fields were determined by MPN (most probable number) method (Fig.…”

Culture-dependent characterization of hydrocarbon utilizing bacteria in selected crude oil-impacted sites in Bodo, Ogoniland, Nigeria

“…Hydrocarbons interact with the environment and microorganisms determining the fate of the contaminant relative to their chemical nature and microbial degra-dative capabilities respectively. Provided the polluted has requisite values for environmental factors that influence microbial activities and there are no inhibitors of meta-bolism, there is a good chance that there will be a viable and active population of hydrocarbon utilizing micro-organisms in the environment (Chikere et al, 2011(Chikere et al, , 2012b. Considering the large quantity of oil going into the Niger Delta environment especially farmlands and rivers, the need to cleanup crude oil contaminated sites has become a key environmental issue (Vincent et al, 2011).…”

Biostimulation proved to be the most efficient method in the comparison of in situ soil remediation treatments after a simulated oil spill accident

“…Experimental and case studies have shown that autochthonous bacterial communities are capable of adapting to oil contamination and degradation of oil-derived compounds (Acosta-González et al 2015; Oliveira et al 2013; Chikere et al 2012; Bento et al 2005). LH-PCR has been proved to be a sensitive method to monitor the successional changes in bacterial community (Yan et al 2016; Mikkonen et al 2014).…”