MERcury CLean-Up system based on Bioremediation by marine bacteria

Marine microorganisms hold the genetic potential for Hg detoxification.
MER-CLUB projects aims to unreveil and exploit it for the bioremediation of Hg-contaminated marine sediments.

Why mercury (Hg) pollution is a critical problem worldwide?

Since the industrial era, mercury levels in the environment have increased considerably, reaching critical concentrations that can impact the health of organisms and entire ecosystems. Industrial mercury pollution is harmful for the marine environment at local, regional and global levels. At a local level, some industries using mercury in their technology have released large amounts of mercury in in their vicinity, creating a persistent pollution problem in the environment. More globally, some forms of mercury pollution are volatile and once they reach the atmosphere, they can travel large distances and precipitate far from their source.

Microbial Methylmercury (MeHg) formation

In aquatic systems, the most abundant mercury forms (i.e. Hg0 and Hg2+) can be biologically and chemically transformed by methylation to the highly toxic and soluble organic form methylmercury (MeHg). Some prokaryotes inhabiting marine sediments harbour hgcAB genes, which enable them to convert inorganic mercury (Hg2+) to MeHg, which can be released into the seawater.

Methylmercury (MeHg) in marine ecosystems

MeHg released from sediments in seawater is incorporated into the aquatic food webs by microscopic planktonic organisms and subsequently bioaccumulated along the food web. Mercury concentration increases with trophic position, which means that large fishes contain more mercury than small fishes. This is called biomagnification and, in the case of mercury, this is of special concern because high mercury concentrations in commonly consumed fishes might have dramatic negative effects on human health. In parallel with this process, some bacteria harbouring merB genes are able to demethylate soluble MeHg, converting it back into the ionic form Hg2+. This degradation process, which takes place naturally in the environment, can also represent a biotechnological solution for the bioremediation of MeHg-polluted water or sediments, as we will explore in MER-CLUB.

Ionic mercury reduction and volatilization

Some environmental bacteria harbouring merA genes are able to carry out a further step in mercury detoxification, by reducing the ionic form Hg2+ to the elemental form Hg0, which escapes into the atmosphere. While in the environment this process contributes to the atmospheric mercury long-range transport, it can also represent an interesting biotechnological solution, by removing mercury from sediments by volatilization and subsequent immobilization, as we will explore in MER-CLUB.



Restoring marine sediments will improve the quality of seawater, the health of marine ecosystems and, ultimately, human health.


Deep fundamental understanding of the biological mechanisms controlling mercury cycling in aquatic systems.


The potential for transferability of the MER-CLUB technology as a pre-marketable mercury clean-up system is enhanced by the participation of the SME AFESA Medio Ambiente S.A., experts in Hg decontamination.

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