User:Ezqsun/sandbox

Bioremediation
Bioremediation of oil contaminated soils, marine waters and oily sludges in situ is a feasible process as hydrocarbon degrading microorganisms are ubiquitous and are able to degrade most compounds in petroleum oil. In the simplest case, indigenous microbial communities can degrade the petroleum where the spill occurs. In more complicated cases, various methods of adding nutrients, air, or exogenous microorganisms to the contaminated site can be applied. For example, bioreactors involve the application of both natural and additional microorganisms in controlled growth conditions that yields high biodegradation rates and can be used with a wide range of media.

Two well-known oil spills exemplify large scale marine bioremediation applications:

In 1989, the Exxon Valdez ran aground, spilling 41.6 million liters of crude oil, and launching one of the first major bioremediation efforts for an oil spill. Cleanup of Alaskan shorelines relied in part on fertilizer application to augment bacterial growth.

In 2010, the BP Deepwater Horizon oil spill released 779 million liters of oil into the Gulf of Mexico. This was the largest oil spill of all time and indigenous petroleum microorganisms played a major role in petroleum degradation and cleanup.

Bioremediation
Bioremediation of oil contaminated soils, marine waters and oily sludges in situ is a feasible process as hydrocarbon degrading microorganisms are ubiquitous and are able to degrade most compounds in petroleum oil. In the simplest case, indigenous microbial communities can degrade the petroleum where the spill occurs. In more complicated cases, various methods of adding nutrients, air, or exogenous microorganisms to the contaminated site can be applied. For example, bioreactors involve the application of both natural and additional microorganisms in controlled growth conditions that yields high biodegradation rates and can be used with a wide range of media.

Crude oils are composed of an array of chemical compounds, minor constituents, and trace metals. Making up 50-98% of these petroleum products are hydrocarbons with saturated, unsaturated, or aromatic structures which influence their biodegradability by hydronocarbonclasts. The rate of uptake and biodegradation by these hydrocarbon-oxidizing microbes not only depend on the chemical structure of the substrates, but is limited by biotic and abiotic factors such as temperature, salinity, and nutrient availability in the environment.

Alcanivorax borkumensis
A model microorganism studied for its role in hydrocarbon catabolism and bioremediation of oil-spill sites is the alpha-proteobacteria Alcanivorax, which degrades aliphatic alkanes through its metabolic activities. Alcanivorax borkumensis utilizes linear hydrocarbon chains in petroleum as its primary energy source under aerobic conditions. When further supplied with sufficient limiting nutrients such as nitrogen and phosphor, it grows and produces surfactant glucolipids to help reduce surface water tension and enhance hydrocarbon uptake.[5] For this reason, nitrates and phosphates are often commercially added to oil-spill sites to engage quiescent populations of A. borkumensis, allowing them to quickly outcompete other microbial populations and become the dominant species in the oil-infested environment.

The addition of rate-limiting nutrients promotes the microbe’s biodegrading pathways, including upregulation of genes encoding multiple alkane hydroxylases that oxidize various lengths of linear alkanes. These enzymes essentially remove the problematic hydrocarbon constituents of petroleum oil while A. borkumensis simutaneously increases synthesis of anionic glucoproteins, which are used to emulsify hydrocarbons in the environment and increase their bioavailability. The presence of crude oil along with appropriate levels of nitrogen and phosphor catalyzes the removal of petroleum either by mechanisms that enhance the efficiency of substrate uptake or by direct biodegradation of aliphatic chains.

Commercial applications
Two well-known oil spills exemplify large scale marine bioremediation applications:

In 1989, the Exxon Valdez ran aground, spilling 41.6 million liters of crude oil, and launching one of the first major bioremediation efforts for an oil spill. Cleanup of Alaskan shorelines relied in part on fertilizer application to augment bacterial growth.

In 2010, the BP Deepwater Horizon oil spill released 779 million liters of oil into the Gulf of Mexico. This was the largest oil spill of all time and indigenous petroleum microorganisms played a major role in petroleum degradation and cleanup.

Ezqsun (talk) 21:35, 7 October 2017 (UTC)