Crude Oil Bioremediation: From Bacteria to Microalgae

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.