Diesel bug is contamination of

diesel fuel Diesel fuel, also called diesel oil, heavy oil (historically) or simply diesel, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a re ...

by microbes such as

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

and

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. Water can get into diesel fuel as a result of condensation, rainwater penetration or

adsorption Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a ...

from the air — modern

biodiesel Biodiesel is a renewable biofuel, a form of diesel fuel, derived from biological sources like vegetable oils, animal fats, or recycled greases, and consisting of long-chain fatty acid esters. It is typically made from fats. The roots of bi ...

is especially

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

. The presence of water then encourages microbial growth which either occurs at the interface between the oil and water or on the tank walls, depending on whether the microbes need oxygen. Species which may grow in this way include: * bacteria — ''

Clostridium ''Clostridium'' is a genus of anaerobic, Gram-positive bacteria. Species of ''Clostridium'' inhabit soils and the intestinal tracts of animals, including humans. This genus includes several significant human pathogens, including the causative ...

''; ''

Desulfotomaculum ''Desulfotomaculum'' is a genus of Gram-positive, obligately anaerobic soil bacteria. A type of sulfate-reducing bacteria, ''Desulfotomaculum'' can cause food spoilage in poorly processed canned foods. Their presence can be identified by the re ...

''; ''

Desulfovibrio ''Desulfovibrio'' is a genus of Gram-negative sulfate-reducing bacteria. ''Desulfovibrio'' species are commonly found in aquatic environments with high levels of organic material, as well as in water-logged soils, and form major community member ...

''; ''

Flavobacterium ''Flavobacterium'' is a genus of Gram-negative, nonmotile and motile, rod-shaped bacteria that consists of 130 recognized species. Flavobacteria are found in soil and fresh water in a variety of environments. Several species are known to cause ...

''; '' Acidovorax facilis''; ''

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 348 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a ...

''; ''

Sarcina The ''sarcina'' was the marching pack carried by Roman legionaries, the heavy infantry of the Roman legions. Most of a legionary's equipment other than his arms and armour would, in early times, have been consigned to a baggage train and ...

'' * fungi — ''

Aspergillus ' () is a genus consisting of several hundred mold species found in various climates worldwide. ''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...

''; ''

Candida keroseneae ''Candida keroseneae'' is a species of yeast in the genus ''Candida'', family Saccharomycetaceae. Described as new to science in 2011, it was isolated from aviation fuel. Taxonomy The type strain of this yeast (IMI 395605T) was isolated from ai ...

''; ''

Fusarium ''Fusarium'' (; ) is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the s ...

''; '' Hormoconis resinae'' Fuel companies agree that if left untreated fuel will remain reliable for just 6–12 months, after which fuel contamination (such as the diesel bug) begins to appear. Most industrial engine manufacturers now recommend a fuel conditioning programme to ensure the reliability of fuel.

References

External links

Stored Fuel for Back Up Generators
- including "How to minimize the risk of fuel contamination occurring" {{engineering-stub Diesel fuel