Since the 1976 Viking missions, when NASA first successfully placed uncrewed landers on Mars, scientists who study life in the universe, known as astrobiologists, have been gathering evidence to determine whether microorganisms ever lived on the red planet. It has been a challenging determination to make. Until a Mars sample return mission occurs, all necessary analyses must take place on Mars, using instruments designed as much to withstand the stresses of space travel as to collect data, which limits how thoroughly scientists can study Martian rocks. As a result, the search for evidence of microbial life on Mars is inherently incremental. 

Recently, scientists added another piece of exciting, yet inconclusive, evidence to their search. In the summer of 2024, the Mars 2020 Perseverance Rover science team was searching for signs of ancient microbial life in a 3,700-million-year-old lake bed on Mars, known as Jezero Crater. In the process, they detected complex, carbon-containing organic molecules in mudstones within a river channel that once brought water to the now-dry lake bed. 

This is not the first time complex organic molecules have been detected in Martian mudstones. However, there are 2 reasons that astrobiologists are particularly interested in this new discovery. First, these organic molecules are widely dispersed across all 4 river channel mudstones they analyzed. Second, some of the organic molecules they found are associated with minerals that are known to support microbial life on Earth. 

Widely dispersed organic molecules associated with minerals that can support microbial life are exactly what astrobiologists would expect to see if microorganisms once lived in Jezero Crater. However, organic molecules can also form through geological processes, like when gases and minerals react at high temperatures and pressures at deep-sea vents on Earth. Therefore, astrobiologists must carefully assess organic molecules to determine their origin. 

In July of 2026, more than 60 Perseverance science team members took a first step towards determining whether ancient microorganisms could have made the organic molecules found in Jezero Crater. They compared the organic molecule detections in Martian mudstones to similar detections of organic molecules in samples of known origin, including fossilized Earth life, meteorites, and minerals. 

NASA scientists detected the organic molecules in Jezero Crater with a rover instrument called Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC). SHERLOC uses a 248.6 nanometer (nm) wavelength laser to excite molecules in unknown materials. When molecules are excited, they absorb and scatter the laser light, causing characteristic shifts in the wavelength of the scattered light. 

Instruments like this, known as Raman spectrometers, detect the shifted light and display the detections as lines called spectra, which scientists use to identify the unknown molecules. The Raman spectra from the 4 mudstones in Jezero crater showed shifts of about 1600 nm, which is characteristic of complex carbon molecules. These shifts appear as bands in the spectra that are often called G-bands.

Raman spectrometers are common laboratory instruments, but most use lasers with wavelengths of 485 nm or higher, so the spectra they produce can be slightly different from SHERLOC spectra even when the laser excites the same kind of molecule. To get around this issue, the scientists compared the Mars spectra with spectra of complex carbon molecules from fossilized Earth microorganisms, coal, graphite, meteorites, and synthetic samples collected by Raman instruments using the same wavelength laser that SHERLOC uses. They found that the spectra collected on Mars overlap with at least one example from every sample type except graphite. 

These results don’t rule out the possibility that organic molecules in Jezero Crater were produced by ancient microbial life, but they can’t tell us exactly how they formed either. That determination will have to wait until the samples are brought to Earth so they can be studied with laboratory instruments.

The Perseverance team has made a small but critical contribution towards determining whether microbial life ever inhabited our closest planetary neighbor, Mars. Their efforts exemplify how the science of astrobiology and the search for possible extraterrestrial life slowly and carefully move forward. If we keep at it, humans may one day have a definitive answer to one of our most consequential questions: Are we alone?

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Electric vehicles (EVs) use high-powered rechargeable batteries to store electrical energy that powers their motors. Most EV batteries use a specific mixture of metals to hold the battery’s charge, called nanoscale lithiated nickel manganese cobalt oxides, aka NMC materials. NMC materials can store a large amount of energy, making them ideal for batteries, but the metals themselves can be toxic in soil and water if the batteries are not properly recycled.  

NMC batteries leave behind a specific combination of toxic metals, so researchers can study how bacteria respond to this waste when it enters the environment. By understanding how bacteria adapt to toxic metals, scientists hope to predict how new technologies like EV batteries will affect the environment. 

In 2019, a team of researchers from the University of Minnesota reported that a common soil bacterium called Shewanella oneidensis can rapidly evolve resistance to NMC materials, but they didn’t know how. True beneficial gene evolution usually develops over thousands of generations, but Shewanella oneidensis adapted much more quickly. The team recently conducted a follow-up study to determine the genetic mechanisms behind this bacterium’s unique metal resistance.

They started by analyzing the complete DNA sequences of 33 Shewanella colonies that were resistant to either pure NMC waste or individual metals like nickel and cobalt, using a process called whole-genome sequencing. They expected to find DNA mutations in genes that control how bacteria take up and expel toxic metals that would give the resistant Shewanella an advantage in surviving NMC metal toxicity. However, they didn’t find any DNA mutations in metal-related genes. Instead, they found that a specific DNA region was duplicated 10 to 15 times in all 33 NMC-resistant or metal-resistant colonies. This result suggested to the researchers that a temporary adaptation, not true gene evolution, was responsible for the bacteria’s metal resistance. 

The researchers wanted to know more about the duplicated DNA region in metal-resistant Shewanella, so they focused on 2 gene duplication mechanisms that might serve as temporary adaptations in Shewanella. The first mechanism directly duplicates DNA regions to create extra copies of a gene, via a process called gene duplication amplification. The second mechanism moves DNA segments, called mobile genetic elements, into different DNA sections to create extra copies of a gene. 

To test whether either of these mechanisms was causing the gene duplication in Shewanella, the team grew the bacteria in different liquid media containing only cobalt, only nickel, or cobalt and nickel together. The researchers used a technique that measures the exact amount of DNA in a given sequence, called quantitative polymerase chain reaction (qPCR), to calculate how many duplicated DNA regions were in each genome sequence. They found that neither cobalt nor nickel alone triggered DNA duplication. But the bacteria grown in the media with cobalt and nickel together had 8 additional copies of the DNA region. This suggested that something about the combination of nickel and cobalt triggered gene duplication. 

To determine whether this gene duplication only occurred with nickel and cobalt, the team substituted copper and zinc for nickel in the growth media. They exposed Shewanella cells to different combinations of these metals using a grid pattern in a 96-well plate, a technique called a checkerboard assay. Then they repeated the qPCR process to measure the duplicated DNA region. They found that no other combinations of metals triggered gene duplication, suggesting that nickel and cobalt are especially toxic together, and that the gene duplication responds to this combined toxicity.

Finally, the researchers identified the function of the duplicated DNA region. They found that one of the genes within the region turned on a special protein that pushes metal ions and other toxins out of the cell, called an efflux pump protein. The team hypothesized that this efflux pump protein was responsible for removing cobalt and nickel from the bacteria’s cells. To test this theory, they grew modified Shewanella cells without the efflux pump gene in media containing cobalt, nickel, or cobalt and nickel together. They found that the modified bacteria grew well in the nickel-only treatment, but didn’t grow in the cobalt-only or combined treatments, which indicated that the efflux pump protein is necessary for Shewanella to resist cobalt toxicity. 

Based on their experiments, the team concluded that nickel and cobalt together trigger a gene duplication event in Shewanella oneidensis. This gene duplication event increases the number of efflux proteins in Shewanella that can expel cobalt and underlies its unique NMC resistance. They suggested that future researchers study temporary adaptations similar to gene duplication in bacteria to track how they respond to electronic waste and other new technologies.

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