Crude Oil Bioremediation: From Bacteria to Microalgae

Abstract

Crude oil is one of the major pollutants present. Its extraction and processing generate processing waters contaminated by hydrocarbons which are harmful to both human health and the flora and fauna that come into contact with it. Hydrocarbon contamination can involve soil and water, and several technologies are used for recovery. The most used techniques for the recovery of spilt oil involve chemical-physical methods that can remove most of the pollutants. Among these, must consider the bioremediation by microorganisms, mostly bacterial capable of degrading many of the toxic compounds contained within the petroleum. Microalgae participate in bioremediation indirectly, supporting the growth of degrading bacteria, and directly acting on contaminants. Their direct contribution is based on the activation of various mechanisms ranging from the production of enzymes capable of degrading hydrocarbons, such as lipoxygenases, to the attack through the liberation of free radicals. The following review analyzed all the works published in the last ten years concerning the ability of microalgae to remove hydrocarbons, intending to identify in these microorganisms an alternative technology to the use of bacteria. The advantages of using microalgae concern not only their ability to remove toxic compounds and release oxygen into the atmosphere but their biomass could then be used in a circular economy process to produce biofuels.

Microbial communities in petroleum refinery effluents and their complex functions

“…Microalgae have a role in bioremediation through two primary mechanisms: indirect participation by fostering the growth of degrading bacteria, and direct action on pollutants. Their primary contribution is derived from the activation of many processes, encompassing the synthesis of hydrocarbon-degrading enzymes, such as lipoxygenases, as well as the assault through the release of free radicals ( Radice et al, 2023 ).…”

“…Although the exact mechanism by which microalgae bioremediate petroleum remains unclear, two main theories have been proposed: first, that they consume organic carbon derived from hydrocarbons; or second, that they store these toxins internally as a defense mechanism and treat them as an actual pollutant ( Radice et al, 2023 ).…”

Progress of Crude Oil Gasification Technology Assisted by Microorganisms in Reservoirs

“…Consequently, the crude oil gasification flora can be broadly categorized into two groups: interacting hydrocarbon-degrading flora and methanogenic bacteria, which are responsible for the initial degradation and final methanogenic processes, respectively. Researchers isolated, screened, and enriched interbacterial communities involved in crude oil hydrocarbon degradation from diverse habitats [36][37][38][39][40], as shown in Table 2. These communities primarily consist of hydrocarbon-oxidizing bacteria, fermentation bacteria, and various reducing bacteria.…”

Eco-Insights on Hydrocarbon Bioremediation

“…Short-chain hydrocarbons can be more easily transported through the environment and therefore can spread over larger areas, unlike long-chain and branched hydrocarbons that do not have this mobility but are more persistent in the environment. Also, the ability of PHCs to interact with biological membranes and eventually harm organisms is dependent on their physical and chemical properties, which control their bioavailability and toxicity [7,8].…”