Nodule approach: Bacteria will help grow rare earth minerals on the seabed

Russian researchers have discovered and studied communities of microbes that are involved in the formation of ores with useful elements on the seabed. These bacteria can become the basis for the development of technologies for the "cultivation" of minerals, including rare earth metals, in the shelf zone and the purification of water areas from industrial wastewater. So far, these possibilities have been poorly studied, and the proposed technologies can be implemented only in the distant future. However, available resources are rapidly being depleted, so it is necessary to look for alternative sources, experts noted in an interview with Izvestia.

How microbes help ore grow

Russian scientists have identified microorganisms that promote the growth of ferromanganese nodules, ore formations on the seabed. According to the researchers, in the future, by learning how to control these processes, it will be possible to artificially "grow" minerals. The work was attended by specialists from Lomonosov Moscow State University, the P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences, the S.N. Vinogradsky Institute of Microbiology of the Russian Academy of Sciences and the I. Kant Baltic Federal University.

— Nodules consist of accumulations of iron and manganese hydroxides, and also contain impurities of copper, cobalt, nickel and other elements, including rare earth metals. In the depths of the ocean, such formations grow slowly — about a millimeter per million years, but on the sea shelf it happens thousands of times faster. For example, at the bottom of the Baltic Sea, their growth rate can reach several millimeters in 100 years," Valery Lisun, a graduate student at the Faculty of Biology at Moscow State University, told Izvestia.

Modern data indicate that in addition to chemical precipitation, microorganisms play an important role in this process, he noted.

During the study, scientists took samples from the Gulf of Finland. Some of the material was used for DNA analysis, while the other part was used to produce storage cultures that were grown in the laboratory. The experiments allowed us to identify communities of microorganisms that are closely related to the nodule surface.

DNA analysis has shown that groups of bacteria and archaea are present on the mineral formations, which are practically absent in the surrounding sediment. Among them, microorganisms capable of oxidizing manganese and iron predominate, as well as species involved in the transformations of nitrogen and sulfur compounds.

According to Valery Lisun, it is still difficult to say that these microbes "build" a nodule. At the same time, the study showed that they form microzones with conditions in which minerals are deposited much more actively. In fact, they act as catalysts for natural ore formation.

In the future, such microorganisms can be used to purify industrial wastewater. For example, they can be used to collect dissolved metals into larger conglomerates and then extract them.

Why mining resources on the ocean floor can be dangerous

— Nodules are polymetallic ores with a complex ecosystem inside. Microbes get into them from bottom sediments. Due to the directed natural selection, certain types of bacteria are fixed in them. Through their joint activities, they are able to accelerate the growth of these formations at the bottom of the seas and oceans. At the same time, in order to form such mineral conglomerates, a special combination of environmental parameters is needed, but so far scientists do not fully understand what conditions are necessary. It is unclear why they grow in some areas and not in others, although the conditions are comparable," said Natalia Shulga, senior researcher at the Laboratory of Ocean Chemistry of the IO RAS.

In particular, there are two types of such mineral formations in the Baltic, with a predominance of iron or manganese. Studies have shown different adaptations of the microbial community to their geochemistry. Therefore, it is difficult to artificially grow such formations at the bottom, but it is not necessary, she noted.

Sift through phyto: rare earth metals will be extracted using mustard

How grasses and shrubs will help increase the production of chemicals valuable for industry

According to her, extraction of resources from the ocean floor can carry environmental risks. These ecosystems are almost unexplored: up to 90% of the species found there are new, and no one can predict what damage will be done to nature.

The specialist noted that the use of microbes to extract valuable elements from landfills is currently promising. Before going into the ocean, you should think about recycling discarded mobile phones, printed circuit boards and other electronics that contain lithium, tellurium, rare earths and other valuable metals. Accumulations of such debris can be considered man-made deposits.

How to turn waste into a renewable resource

— The traditional proven reserves of strategic metals are in an active stage of development. Non-standard mining methods should complement traditional approaches. The research of scientists shows that microorganisms are active participants in ore genesis, which means that it is possible to develop methods for controlled concentration of metals," Vitaly Sanin, head of the Laboratory of Metallurgical processes at Giredmet JSC (Rosatom chemical technology cluster), told Izvestia.

A similar logic underlies phytomining, when accumulator plants extract rare earth metals from man-made substrates (phosphogypsum, enrichment tailings) and concentrate them in biomass. Such technologies are being developed in Russia. In fact, this is also a "biological ore formation," the expert noted.

"The practical significance of the research is that it outlines a path to the isolation of pure cultures and the subsequent controlled synthesis of nodules enriched in metals (for example, cobalt and nickel) and related rare earth elements," added Vitaly Sanin.

According to him, the most realistic scenario for the industrial introduction of technologies is offshore zones, where man—made emissions from iron and manganese enter. Controlled microbiota seeding can accelerate the deposition and concentration of metals and rare earths, turning industrial waste into a renewable resource.

At the same time, the approach requires an analysis of the impact of introduced microbes on bottom ecosystems, so that the introduction of microorganisms does not lead to irreversible changes in the biogeochemical balance of the sea.

— Mineral deposits are rapidly being depleted. In this regard, the search for alternative ways to obtain mineral components for the needs of mankind is becoming increasingly relevant. The results obtained can pave the way to the creation of microbial communities with the desired properties — a high potential for the synthesis of products needed by humans," says Elena Mikheeva, associate professor of the Department of Geology and Emergency Management at Ural State Mining University.

To implement such technologies, it will be necessary to go through several stages: to isolate pure cultures of microorganisms, and possibly to apply genetic engineering methods and create new high-tech bio-productions. However, all these processes are already well known to science, so there are chances for successful application of the development, the expert concluded.