"It's not just about cleaning, but about achieving healthier ecosystems"

The results obtained from a line of basic research on metabolic pathways of the biogeochemical nitrogen cycle in haloarchaea were the origin of my interest in bioremediation. At that time — the late 1990s— I was studying the enzymes that catalyze assimilatory nitrate reduction and denitrification reactions.

We found that some species of haloarchaea —extremophilic microorganisms living in hypersaline environments— were capable of growing in the presence of high concentrations of nitrate, nitrite, and ammonium. We demonstrated that Haloferax mediterranei could grow in the presence of up to 2 M potassium nitrate or 45 mM potassium nitrite —nitrite is toxic for most living organisms at concentrations above 2 mM. These concentrations remain the highest ever reported in the literature regarding microbial tolerance.

Given that these microorganisms grow in brines and tolerate such high concentrations of nitrogen compounds, I thought they could be a tool for removing nitrate, nitrite, and ammonium from saline waters. The theoretical approach was well received, especially because there were already collapse episodes in ecosystems near our university, such as the Mar Menor in Murcia, where massive fertilizer use was causing massive water pollution with nitrogen compounds.

Switching research lines was a challenge in itself. When applying for funding, I faced the limitation of having no prior experience working in bioremediation, making it difficult to secure competitive research grants.

The second major challenge was capturing the attention of companies in the water treatment sector.

After an initial phase focused on removing nitrogen compounds from brines, we were surprised to find that some haloarchaea species were especially tolerant even to other compounds like oxychlorides. We decided to continue monitoring haloarchaeal tolerance to other pollutants such as heavy metals and metalloids.

I would greatly strengthen education and public outreach to minimize or slow down the processes that lead to environmental pollution —we are still far from showing responsible behavior toward the environment— and secondly, I would always focus the study on integral ecosystemic solutions, rather than just "cleaning" an environment.

In my view, it's not just about cleaning water, soil, and air from pollutants —which almost always come from anthropogenic action— but about achieving healthier ecosystems in the broadest sense. The One Health concept taken to the extreme.

Don't get discouraged or dismiss the idea of researching this field. The planet is already sending distress signals. We are stressing natural cycles and the availability of large natural reserves of raw materials, while pollution indices not only stagnate but keep rising.

The search for solutions for the common good —solutions that restore natural balances and eliminate pollution— will be essential in the coming decades to ensure equitable human development and a healthy natural environment.