As the usage of petroleum hydrocarbon products increases, soil contamination with diesel and engine oils is becoming one of the major environmental problems. To investigate the countermeasure to remediate soils contaminated with oils, bioremediation provide an effective and efficient strategy to speed up the clean-up processes. Three bacterial isolates capable of utilizing used engine-oil as a carbon source were isolated from contaminated soils using the enrichment technique. Three isolates were identified as Flavobacterium sp., Acinetobacterium calcoaceticum and Pseudomonas aeruginosa based on biochemical tests and 16S rRNA sequencing. The gavimetric analysis revealed that A. calcoaceticum and a consortium of the isolates were capable of utilizing 80 and 90% of used engine oil, respectively, under laboratory conditions at 30°C and 160 rpm with Bushnell-Haas media in a 4 week period. An increase in oil degradation is correlated to an increase in cell number indicating that the bacterial isolates were responsible for the oil degradation. All isolates were capable of degrading the nparaffin up to 80% in a 2 week period. The optimal temperatures at which biodegradation occurred at 30–37°C. The preference of nitrogen sources and minimal salts were different for different bacterial isolates. The results obtained demonstrate the potential for oil bioremediation of these isolates in situ and/or ex situ.

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Isolation and characterization of engine oil degrading indigenous microrganisms in Kwazulu-Natal, South Africa

Widespread pollution of terrestrial ecosystems with petroleum hydrocarbons (PHCs) has generated a need for remediation and, given that many PHCs are biodegradable, bio- and phyto-remediation are often viable approaches for active and passive remediation. This review focuses on phytoremediation with particular interest on the interactions between and use of plant-associated bacteria to restore PHC polluted sites. Plant-associated bacteria include endophytic, phyllospheric, and rhizospheric bacteria, and cooperation between these bacteria and their host plants allows for greater plant survivability and treatment outcomes in contaminated sites. Bacterially driven PHC bioremediation is attributed to the presence of diverse suites of metabolic genes for aliphatic and aromatic hydrocarbons, along with a broader suite of physiological properties including biosurfactant production, biofilm formation, chemotaxis to hydrocarbons, and flexibility in cell-surface hydrophobicity. In soils impacted by PHC contamination, microbial bioremediation generally relies on the addition of high-energy electron acceptors (e.g., oxygen) and fertilization to supply limiting nutrients (e.g., nitrogen, phosphorous, potassium) in the face of excess PHC carbon. As an alternative, the addition of plants can greatly improve bioremediation rates and outcomes as plants provide microbial habitats, improve soil porosity (thereby increasing mass transfer of substrates and electron acceptors), and exchange limiting nutrients with their microbial counterparts. In return, plant-associated microorganisms improve plant growth by reducing soil toxicity through contaminant removal, producing plant growth promoting metabolites, liberating sequestered plant nutrients from soil, fixing nitrogen, and more generally establishing the foundations of soil nutrient cycling. In a practical and applied sense, the collective action of plants and their associated microorganisms is advantageous for remediation of PHC contaminated soil in terms of overall cost and success rates for in situ implementation in a diversity of environments. Mechanistically, there remain biological unknowns that present challenges for applying bio- and phyto-remediation technologies without having a deep prior understanding of individual target sites. In this review, evidence from traditional and modern omics technologies is discussed to provide a framework for plant-microbe interactions during PHC remediation. The potential for integrating multiple molecular and computational techniques to evaluate linkages between microbial communities, plant communities and ecosystem processes is explored with an eye on improving phytoremediation of PHC contaminated sites.

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The Interaction between Plants and Bacteria in the Remediation of Petroleum Hydrocarbons: An Environmental Perspective

Ex situ bioremediation of oil-contaminated soil

Diesel removal from contaminated soils by biostimulation and supplementation with crop residues

http://sites.bsyse.wsu.edu/ndegwa/main/publications/downloads/Publication%20list/Article%208.pdf

Bioremediation of oil-contaminated soil using Candida catenulata and food waste.

Biodegradation of diesel oil was performed using adiesel oil-degrading bacterial consortium, in bothlaboratory and pilot scale experiments. The bacterialconsortium was prepared in liquid for laboratory testsand for pilot scale experiments, it was prepared intwo steps, liquid and then in soil. The concentrationof diesel in soil treated with the bacterialconsortium was reduced to <15% of the initialconcentration, within a period of five weeks in bothlaboratory (135 to 19.32 g diesel kg (soil dryweight)-1) and pilot scale (118 to 17.5 g dieselkg (soil dry weight)-1) experiments, incomparison with controls (without bacterialconsortium), in which initial concentration of dieselwas reduced by only 5 and 15%, respectively. Dieselbiodegradation rate with the bacterial consortium was2.13 g diesel kg (soil dry weight)-1 d-1, itwas slightly enhanced by the addition ofNH4NO3 in the presence of bacterialconsortium 2.78 g diesel kg (soil dry weight)-1d-1. The enhancement of the microbial activity inhydrocarbon-contaminated soil can be achieved with thecombination of stepwise soil inoculation and nutrient additions.

Vanessa Hernández-Rodrí

Papers

Biodegradation of diesel oil in soil by a microbial consortium