La Jornada: UNAM scientists investigate bacteria that degrade hydrocarbons

In the Gulf of Mexico there are bacteria capable of degrading hydrocarbons and using them as a source of energy. This natural process, not very visible but fundamental, has been studied by researchers from the Institute of Biotechnology of the National Autonomous University of Mexico (UNAM), who have identified that between 10 and 20 percent of the microorganisms analyzed in the region have this capacity.

“Oil originated from organic matter that, when compressed and subjected to the temperatures and pressures during the formation of the gulf, was trapped in deposits on the seabed. Therefore, microorganisms live in that region that, over millions of years, have developed the ability to adapt and degrade these compounds,” he explains to The Day Liliana Pardo López, who heads the Marine Biotechnology Laboratory.

Since 2015, she and her team have carried out expeditions in these waters aboard the oceanographic vessel Justo Sierra. From the coasts of Tamaulipas to the Caribbean, passing through Veracruz, Tabasco and Campeche, they have collected water samples at depths of up to 4 thousand meters.

Although many of the bacteria cannot be grown in the laboratory, due to the difficulties in reproducing deep-sea conditions, scientists have turned to techniques such as metagenomics to obtain their DNA and identify the species present. With this, they have built an atlas of the microorganisms that inhabit the Gulf of Mexico, from the surface to 4 thousand meters deep. They currently have a strain of more than 400 cultivable bacteria with the capacity to degrade hydrocarbons.

A bacterial consortium composed of three species stands out, among them Alcanivoraxspecialized in degrading alkanes. “One of them first degrades the simplest compounds in oil, while the other two take advantage of the products that result from this process. Together, they act as a chain that degrades the oil in stages,” explains Pardo López.

One of the most relevant aspects of these microorganisms is that, after consuming the hydrocarbon as a source of energy, they transform it into carbon dioxide and water. “It is a very ecological way of acting against a pollutant,” he points out.

The researcher points out that the degradation of oil by bacteria is not a magical process. In the case of the bacterial consortium, it manages to decompose up to 50 percent of the oil. “At the end of its action, the result is less toxic and represents an important advance, but further research is still necessary.”

Faced with hydrocarbon pollution in the Gulf of Mexico, the scientist points out that options have also been explored, such as the use of human hair to absorb oil in bodies of water. Although this technique works as a barrier that contains the contaminant, it does not eliminate it.

“Unlike this method, microorganisms have the ability to degrade the compounds and transform them into less toxic substances.”

Mobile laboratory

In addition to the experimentation at the institute, where microcosms have been recreated, the researchers are advancing towards a second stage: a mobile laboratory in Tuxpan, Veracruz, financed by the Ministry of Science, where they will test them in tanks holding a thousand liters of seawater.

“We are going to corroborate that these bacteria that have worked very well in controlled conditions can also do so in an environment closer to the natural one.”

Looking to the future, the scientific team hopes to work on three lines: produce them in large quantities to put them to work, test them in polluted rivers, and develop marine robotics that allow them to be taken to places that are difficult to access.

For Pardo López, we are getting closer to these bacteria resulting in technologies or protocols for marine bioremediation.