Self-healing capacity of deep-sea ecosystems affected by petroleum hydrocarbons: Understanding microbial oil degradation at hydrocarbon seeps is key to sustainable bioremediation protocols.

Abstract

Crude oil or petroleum is a naturally occurring liquid that was formed in geological sediments from organic material under high hydrostatic pressure (HP). It has enormous economic importance as the basis for fuels, plastics, and a huge range of chemicals; the global economy consumes about 30 billion barrels of oil, or 4.8 cubic kilometers, each year. Much of this annual production comes from offshore oilfields and/or is shipped across the world, which poses a considerable risk of accidents and oil spills that contaminate the marine environment. The Exxon Valdez (1989), Prestige (2002), or Deepwater Horizon (DWH) offshore platform (2010) disasters affected huge areas of the oceans and adjacent shores with devastating impact on the fauna and flora. There is therefore huge interest in technologies to clean up spilled oil at shores and in the deep seas. This in turn has triggered interest in natural biodegradation processes by microorganisms that are able to break down oil and thereby remove it from the environment. These oil‐consuming archaea and bacteria thrive around natural marine hydrocarbon seepages, such as the spectacular hydrothermal black smokers or the cold hydrocarbon seeps that were first discovered in the Gulf of Mexico and in subduction zones of the Pacific Ocean [1]. Recent research showed that these hydrocarbon springs at depths of 200–3,500 m below surface level (bsl) fuel fantastic and highly diverse deep‐sea ecosystems, spanning from asphalt and oil seeps, hypersaline lakes, and gas chimneys, to mud volcanoes and pockmarks. The amount of oil that is naturally entering the oceans at these sites is estimated to be more than 700 million liters per year [2]. In contrast, anthropogenic oil spills into marine environments are estimated to amount to more than 120 million liters per year [2]. The main causes are routine operations—drilling, …