Petroleum Hydrocarbons

On this page (7 sections)

1. What Elm Dirt does about fuel in soil
2. What it is
3. Where it comes from
4. Why it matters
5. What the research shows about microbes in our products
6. What to expect
7. Studies

What Elm Dirt does about fuel in soil

Hydrocarbons are carbon chains, and a large group of soil organisms eats them. Fuel is the most established use of biology in remediation for that reason.

We apply living biologicals and Class A compost carrying organisms that peer-reviewed research shows can degrade fuel-range hydrocarbons and the aromatic compounds that travel with them. Air goes in as part of the same job. Fuel degradation needs oxygen, and on compacted or saturated ground, aeration often does more than inoculation.

A spill also floods the soil with carbon while nitrogen and phosphorus stay put, and that shortage becomes the bottleneck, which compost and biologicals correct. Heavy fuel coats soil particles, pushes out oxygen and kills the existing biology, so fuel-affected ground often won’t grow plants even after the visible spill is gone. Rebuilding that biology is part of the work. We go through local applicators, and an independent lab samples on a schedule.

What it is

Diesel, gasoline, jet fuel and heating oil are each mixtures of hundreds of compounds, and a lab report usually sorts them by carbon chain length into gasoline, diesel and heavier oil ranges.

Chain length predicts how a site behaves. The short chains evaporate and move, while mid-range chains, roughly C12 to C18, make up the bulk of diesel and are what biology handles best. The heaviest fraction, asphaltenes included, barely moves and barely degrades.

Alongside the chains sit the BTEX compounds: benzene, toluene, ethylbenzene and the xylenes. They are the most soluble and mobile part of a fuel release, and benzene drives most regulatory decisions.

Where it comes from

• Underground storage tanks, of which about 542,000 operate nationwide, hold petroleum or hazardous substances, and EPA says the greatest potential threat from a leaking tank is groundwater contamination, and groundwater supplies drinking water for nearly half of all Americans [1].
• Above-ground tanks, pipelines and transfer areas
• Derailments and truck accidents, where fuel spills and often burns
• Equipment yards, fueling stations, rail yards and maintenance shops
• Former industrial and military sites

Fuel sinks through soil until it hits a barrier or the water table, smearing contamination through the soil column on the way down.

Why it matters

Fuel in soil threatens groundwater, sends vapor into nearby buildings, and wrecks soil health. Benzene is mobile and a known human carcinogen, so the BTEX fraction usually sets the cleanup target.

What the research shows about microbes in our products

Independent lab analysis (Biome Makers) identified these organisms in Elm Dirt products, and peer-reviewed research shows each can act on fuel hydrocarbons or the BTEX fraction.

Organism	What the research documents
Pseudomonas putida	Member of the consortium in a 365-day diesel field study, which gave the highest efficiency of the treatments tested [2]. A refinery-soil strain depleted 40 percent of a BTEX mixture in 36 hours [3]
Variovorax paradoxus	Degrades all six BTEX compounds, both with normal oxygen and at 0.5 mg/L dissolved oxygen, with no significant difference between the two [4]. A consortium built on it cleared a 20 mg/L BTEX mixture in six hours and worked in real contaminated groundwater [5]
Acinetobacter calcoaceticus	82 to 92 percent of C12 to C18 alkanes in 28 days [6]; alkane hydroxylase and aromatic ring-cleavage genes confirmed in the genome [7]; a biosurfactant from the species raises how much contaminant the organisms can reach [8]
Pseudomonas fluorescens	Member of the same 365-day field consortium; naphthalene pathway [2][9]
Pseudomonas oleovorans	The reference alkane monooxygenase system for medium-chain alkanes [10]
Mucor circinelloides	Crude-oil bioremediation by an isolated strain of the species [11]

In the 365-day field study, bioaugmentation gave the best efficiency, and adding a biosurfactant did not notably help [2]. Anyone selling surfactant as the key to a fuel cleanup should be asked about that study. The Variovorax low-oxygen result is useful for a different reason: fuel-soaked ground is usually short of air, the condition where most degraders stall.

What to expect

• Heavy residual fractions degrade slowly, and the asphaltene end barely moves.
• Degradation stops without oxygen, so saturated or compacted soil stalls.
• Very high concentrations poison the degraders, so a hot spot may need to come out before biology handles the rest.
• Expect months for the lighter fraction under good conditions and a year or more for a heavily loaded site, confirmed by independent lab testing.

Studies

1. US Environmental Protection Agency. Underground Storage Tanks. epa.gov/ust
2. Szulc A, et al. (2014). The influence of bioaugmentation and biosurfactant addition on bioremediation efficiency of diesel-oil contaminated soil: feasibility during field studies. Journal of Environmental Management 132:121–128. doi:10.1016/j.jenvman.2013.11.006
3. Chicca I, et al. (2020). Degradation of BTEX mixture by a new Pseudomonas putida strain: role of the quorum sensing in the modulation of the upper BTEX oxidative pathway. Environmental Science and Pollution Research 27(29):36203–36214. doi:10.1007/s11356-020-09650-y
4. Benedek T, et al. (2021). Potential of Variovorax paradoxus isolate BFB1_13 for bioremediation of BTEX contaminated sites. AMB Express 11(1):126. doi:10.1186/s13568-021-01289-3
5. Szentgyörgyi F, et al. (2022). Development of a bacterial consortium from Variovorax paradoxus and Pseudomonas veronii isolates applicable in the removal of BTEX. AMB Express 12(1):4. doi:10.1186/s13568-022-01349-2
6. Ho MT, et al. (2020). Characterization and genomic analysis of a diesel-degrading bacterium, Acinetobacter calcoaceticus CA16, isolated from Canadian soil. BMC Biotechnology 20(1):39. doi:10.1186/s12896-020-00632-z
7. Zeng Y, et al. (2025). Insights into the genomic architecture and improvement of the capabilities of Acinetobacter calcoaceticus for the biodegradation of petroleum hydrocarbons. Microorganisms 13(8):1953. doi:10.3390/microorganisms13081953
8. Zhao Z, Selvam A, Wong JW (2011). Synergistic effect of thermophilic temperature and biosurfactant produced by Acinetobacter calcoaceticus BU03 on the biodegradation of phenanthrene in bioslurry system. Journal of Hazardous Materials 190(1-3):345–350. doi:10.1016/j.jhazmat.2011.03.042
9. Ripp S, et al. (2000). Bioluminescent most-probable-number monitoring of a genetically engineered bacterium during a long-term contained field release. Applied Microbiology and Biotechnology 53(6):736–741. doi:10.1007/s002530000343
10. Smits TH, et al. (2002). Functional analysis of alkane hydroxylases from gram-negative and gram-positive bacteria. Journal of Bacteriology 184(6):1733–1742. doi:10.1128/JB.184.6.1733-1742.2002
11. Yehia RS (2023). Highlighting the potential for crude oil bioremediation of locally isolated Cunninghamella echinulata and Mucor circinelloides. Brazilian Journal of Microbiology 54(3):1969–1981. doi:10.1007/s42770-023-01008-z