Unravelling Diatoms’ Potential for the Bioremediation of Oil Hydrocarbons in Marine Environments

The search for practical solutions to alleviate the destructive impact of petroleum hydrocarbons in marine environments is contributing to the implementation of prospecting strategies for indigenous microorganisms with biodegradative and bioremediation potential. The levels of petroleum contamination entering the marine environment each year have been estimated at around 1.3 million tonnes, a figure that is expected to increase by 1.9% annually over the next decade. The recent interest in decarbonizing our energy system and accelerating the clean energy transition has created a demand for greener technologies and strategies to find innovative, sustainable, and cost-effective treatments for the marine environment. Diatoms (Bacillariophyta) are one of the most diverse and successful taxa in coastal–marine environments and are a relatively untapped pool of biodiversity for biotechnological applications. Recent reports have revealed the significant presence of diatoms associated with oil spills and petroleum hydrocarbon degradation. Most diatoms can secrete substantial amounts of exopolysaccharides (EPSs) into their environment, which can act as biosurfactants that, in addition to oxygen and other enzymes produced by diatoms, create suitable conditions to enhance hydrocarbon solubility and degradation into less toxic compounds in seawater. Recent reports on the biodegradation of aliphatic and aromatic hydrocarbons by diatoms are indicative of the potential of these taxa to achieve success in the bioremediation of hydrocarbons in marine environments. This review highlights the main attributes and roles that diatoms could play in integrated strategies for biodegradation and bioremediation of petroleum hydrocarbon pollutants and as such represent a green, eco-friendly, and sustainable contribution to mitigate damage to biodiversity and value chains of marine ecosystems.