GoKawiilRemember when Japan sent a spacecraft to an asteroid 180 million miles away to scoop some dirt off the surface? Six years on from its arrival to Earth, that sample has yielded some insights about what may have seeded life on our planet. Read on to learn more about the latest findings, and other science news we found interesting this week.
DNA ingredients on Ryugu
In 2020, a capsule from the Japanese space probe Hayabusa2 returned to Earth with samples collected from the surface of asteroid Ryugu, and scientists have spent the subsequent years analyzing those materials for clues about the conditions that existed in the early solar system. This week, researchers from Japan reported an exciting discovery: the Ryugu samples contain the five building blocks of DNA and RNA. The findings, coupled with those from other recent studies, could put us closer to understanding how the ingredients for life first made it to Earth billions of years ago.
The study, published in the journal Nature Astronomy, found the nucleobases adenine, guanine, cytosine, thymine and uracil — all of which were also found in samples gathered from a different asteroid, Bennu, last year, and before that in meteorites dubbed Murchison and Orgueil. This suggests these nucleobases were widespread in the early solar system, and supports the hypothesis that carbonaceous asteroids like Ryugu and Bennu transported them to Earth, the authors explain in the paper. Ammonia was discovered in the samples as well, which may play a role in how these nucleobases formed.
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The discovery of these building blocks "does not mean that life existed on Ryugu," Toshiki Koga, the study's lead author from the Japan Agency for Marine-Earth Science and Technology, told AFP. "Instead, their presence indicates that primitive asteroids could produce and preserve molecules that are important for the chemistry related to the origin of life."
Bacteria collaborate to eat plastic waste
Researchers in Germany have identified a trio of bacteria that can digest a common plastic additive, but only when working together. The study published in the journal Frontiers in Microbiology found that a "consortium" of bacterial strains (two from species in the genus Pseudomonas and one from Microbacterium) was able to break down several phthalate esters (PAEs), which are often used to make plastic materials more flexible. These chemicals are increasingly finding their way into the environment as plastic pollution grows, and research suggests they can have harmful effects on human health and that of wildlife.
The team focused on microbes that could be found right at home in their own lab, taking a sample of biofilm that had formed on the polyurethane tubing of a bioreactor. This sample was then incubated in a growth medium containing the PAE diethyl phthalate (DEP) as the main source of carbon and energy. They eventually ended up with a stable culture of bacteria that could break down DEP, as long as the DEP concentration didn't exceed 888 milligrams per liter, according to a press release. The consortium could gobble up all the DEP in 24 hours at 30 degrees C. It was also able to grow on the PAEs dimethyl phthalate, dipropyl phthalate and dibutyl phthalate.
The researchers identified the bacteria in the consortium through DNA sequencing, but found that they were not individually able to tackle the PAEs, suggesting they break down the chemicals through a "cooperative process" known as cross-feeding. The consortium could make for another tool in the pollution-fighting toolbox, with potential to help break down PAEs in contaminated areas or speed up the degradation of plastics that contain PAEs by making them more brittle. "This approach may also be effective in treating industrial plastic waste streams," they note.
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