Hydrocarbonoclastic bacteria

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Hydrocarbonoclastic bacteria ("hydrocarbon-breaking bacteria", English hydrocarbonoclastic bacteria , abbreviated to HCB) are a group of bacteria that are combined due to their ecological potential to use the oxidation of hydrocarbons as the exclusive source of energy. Therefore the term hydrogenocarbonoclastic bacteria would be more appropriate. They are able to enzymatically break down and break down complex hydrocarbons and accordingly play a major role in the removal of oil pollution, especially in the breakdown of crude oil , in marine and terrestrial ecosystems.

Way of life

HCB probably developed as specialists in the mining of hydrocarbons in the area of ​​naturally occurring petroleum sources in marine ecosystems. They are able to split simple and complex hydrocarbons with the help of various enzymes and degradation chains based on them and to use the oxidation of the split products as an energy source. The different types of bacteria have specialized in different components of the crude oil, which consists of up to 17,000 components, which makes it one of the most complex substances of all.

The bacteria are ubiquitous , so they can be found almost everywhere. As a rule, however, their population density is very low; in clean seawater, for example, they are usually only found in very low concentrations, and they can also use other organic substances as energy and carbon sources. In contrast, large accumulations of these bacteria usually develop in oil-polluted areas, as they find a large supply of usable energy sources here. Alcanivorax borkumensis , for example, has been found worldwide in very small, barely detectable concentrations in seawater. When crude oil is added to clean seawater, its population density increases very quickly. In oil-polluted habitats , the bacterium often represents up to 80 percent of the total bacterial population.

The occurrence and population density of petroleum-degrading bacteria depend on a number of other factors in addition to petroleum as a source of energy and food. These factors primarily include the availability of oxygen and inorganic nutrients and a suitable temperature. Especially in seawater, the nutrients are often the limiting factor for the growth of bacteria. Since the breakdown of hydrocarbons is one of the metabolic processes with the highest oxygen consumption, the availability of oxygen can quickly drop so much that further breakdown is greatly slowed down becomes. This is especially the case in soils, whereas in water the circulation and the high water body usually make enough oxygen available.

Research history

The first bacteria that break down hydrocarbons were discovered, isolated and described in the early 20th century. However, more intensive research has only been carried out since around 1995, when numerous bacteria were found, especially in marine ecosystems, that possess this property and have specialized in the breakdown of crude oil from natural and man-made sources. Today a number of representatives of different genera are known, including Alcanivorax , Cycloclasticus , Marinobacter , Neptunomonas , Oleiphilus , Oleispira and Thalassolitus .

In order to assess the controlled use and use of these bacteria, after their discovery and description, above all the genetic properties and the metabolic processes during the breakdown of the hydrocarbons were researched. In July 2006, the complete genome sequence of the HCB bacterium Alcanivorax borkumensis , which was first discovered in 1998, was published.

See also

literature