Isolation and Characterization of Oil-Degrading Microorganisms for Bench-Scale Evaluations of Autochthonous Bioaugmentation for Soil Remediation

Abstract

Autochthonous bioaugmentation (uses microorganisms indigenous to the target sites) is proposed as a promising remediation technique that can overcome ecological barriers which usually impede successful applications of conventional bioaugmentation remedy. This study aimed to select and characterize strains for bench-scale evaluations of autochthonous bioaugmentation for remediation for oil-contaminated soil. Twentyone oil-degrading stains were isolated from contaminated soil in an oil refinery plant in China. Six strains with high oil-degradation efficiencies were chosen for further morphological and biochemical characterizations, and their biosurfactant production potentials were measured. All six strains were able to produce biosurfactant, and the strain with the highest oil-degradation efficiency had the highest biosurfactant production potential, indicating the important role that biosurfactant played in accelerating biodegradation. Then we prepared the bioaugmentation consortium by mixing equal proportions of these six strains. Microcosm experiments showed that, after 84 days of incubation, the residual oil concentration in bioaugmented microcosms decreased by 63.2± 20.1 % while the residual oil concentration in the control only decreased by 21.3±5.2 %. Gas chromatographymass spectrum analysis further corroborated that 84 days of bioaugmentation significantly reduced the total number of contaminants and changed contaminant composition (resulting in higher relative abundance of shortchain alkanes and lower relative abundance of longchain alkanes). All of these evidence showed that autochthonous bioaugmentation was an effective remediation technology, and the microbial consortium we isolated was an excellent bioaugmentation agent for crude oil-contaminated site.

Isolation, Identification and Degradation Characteristics of Oil Degrading Bacterial Strain

“…There were larger biomass of G-40, when the nitrogen source were (NH 4 ) 2 SO 4 (OD 420 = 0.593), NH 4 Cl (OD 420 = 0.538) and NH 4 NO 3 (OD 420 = 0.500). Compared with the biomass of KNO 3 , there were extremely significant differences.…”

“…From the environment, hydrocarbon can also enter in food chains, leading to health problems. In the body, PAH are mutagenic and can cause a decrease in the immune response with an increased risk of infections [4].…”

Combinations of Surfactant Flushing and Bioremediation for Removing Fuel Hydrocarbons from Contaminated Soils

“…Dry soil samples were sieved to remove particles >2 mm and then mechanically homogenized in a stainless steel rotating mixer. The soil was artificially polluted with diesel fuel to reach an initial TPH concentration of approximately 13 g/kg which was within the range of TPH concentration reported in that contaminated site . Contaminated soil was further mechanically homogenized in a stainless steel rotating mixer and dried under a hood at room temperature for 7 days before being packed into a flow cell.…”

“…In a previous study, 21 hydrocarbon‐degrading microbial strains were isolated from a fuel hydrocarbon contaminated site inside a large oil refinery plant in China . Six strains with the highest hydrocarbon degradation rates ( Pseudomonas (1), Nocardia (2), Streptomyces (3)) were used for the bioaugmentation mixture.…”

“…Bioremediation was conducted using a combination of bioaugmentation and biostimulation. The microbial mixture for bioaugmentation was isolated and characterized in a previous study . Biostimulation was conducted by adding (NH 4 ) 2 SO 4 and KH 2 PO 4 to the flushing fluid.…”