Use of Shotgun Metagenomics to Assess the Microbial Diversity and Hydrocarbons Degrading Functions of Auto-Mechanic Workshops Soils Polluted with Gasoline and Diesel Fuel.

Bioaugmentation is a valuable technique for oil recovery. This study investigates the composition and functions of microbial communities in gasoline- and diesel-contaminated soils of garages Matoko (SGM) and Guy et Paul (SGP) originating from auto mechanic workshops as well as the concentration of soil enzymes ß-glucosidase, ß-glucosaminidase, and acid phosphatase. The work aimed to evaluate the presence of petroleum-hydrocarbon-degrading bacteria for the development of foreseen bioremediation of oil-contaminated soils. Microbial diversity, as given by shotgun metagenomics, indicated the presence of 16 classes, among which Actinobacteria and Gammaproteobacteria dominated, as well as more than 50 families, including the dominant Gordoniaceae (26.63%) in SGM and Pseudomonadaceae (57.89%) in SGP. The dominant bacterial genera in the two soils were, respectively, Gordonia (26.7%) and Pseudomonas (57.9%). The exploration of the bacterial metabolic abilities using HUMANn2 allowed to detect genes and pathways involved in alkanes and aromatic hydrocarbons in the two contaminated soils. Furthermore, enzymes ß-glucosidase, ß-glucosaminidase, and acid phosphatase were found in high concentrations ranging between 90.27 ± 5.3 and 804.17 ± 20.5 µg pN/g soil/h, which indicated active microbial metabolism. The high diversity of microorganisms with a hydrocarbon degradation genetic package revealed that the bacteria inhabiting the two soils are likely good candidates for the bioaugmentation of oil-contaminated soils.

Great Abilities of Shinella zoogloeoides Strain from a Landfarming Soil for Crude Oil Degradation and a Synergy Model for Alginate-Bead-Entrapped Consortium Efficiency.

Oil contamination is of great concern worldwide and needs to be properly addressed. The present work aimed to contribute to the development of bacterial consortia for oil recovery. We investigated the community structure of a landfarming-treated soil (LF2) by metagenomics to unravel the presence of hydrocarbon degraders. Moreover, we isolated Shinella zoogloeoides LFG9 and Bacillus swezeyi LFS15 from LF2 and combined them with Pseudomonas guguanensis SGPP2 isolated from an auto mechanic workshop soil to form the mixed consortium COG1. Bacterial isolates were tested for biosurfactant production. Additionally, the bioremediation potential of COG1 was studied as free and entrapped consortia by gas chromatography-mass spectrometry, in comparison to the single strains. Results revealed the presence of Actinobacteria (66.11%), Proteobacteria (32.21%), Gammaproteobacteria (5.39%), Actinomycetales (65.15%), Burkholderiales (13.92%), and Mycobacterium (32.22%) taxa, indicating the presence of hydrocarbon degraders in soil LF2. All three isolated strains were biosurfactant producers capable of degrading crude oil components within 14 days. However, Shinella zoogloeoides LFG9 performed best and was retained as candidate for further bioremediation investigation. In addition, COG1 performed better when immobilized, with entrapment effectiveness manifested by increased fatty acids and aromatic compound degradation. Attempt to improve crude oil biodegradation by adding surfactants failed as sodium dodecyl sulfate restrained the immobilized consortium performance.