Scientists have discovered a fascinating new type of symbiosis – a bacterium that lives inside a single-celled organism (a ciliate) and provides it with energy. But here’s the twist: unlike mitochondria, which use oxygen, this microbe breathes nitrate to power its host.
A New Discovery in Symbiosis
In 2021, researchers from the Max Planck Institute for Marine Microbiology in Germany made a groundbreaking discovery. They found a bacterium living inside a ciliate that generates energy by respiring nitrate instead of oxygen. This relationship is similar to how mitochondria work in human cells, but with a key difference – no oxygen is needed!
After the initial discovery in a freshwater lake, scientists wanted to find out how common these microbes are. Were they rare, or had they just gone undetected? The answer was surprising.
A Global Presence
By analyzing massive public genetic databases, researchers found that these symbiotic bacteria are everywhere. They appeared in about 1,000 different datasets from around the world. They were not just in lakes but also in groundwater and even wastewater. “We were amazed at how widespread they are,” said Jana Milucka, one of the study’s researchers.
New Members of the Family
The study didn’t just confirm their global presence – it also revealed new species! Scientists identified four new species, including two that formed an entirely new genus. Since these microbes are linked to nitrogen, researchers named the new genus Azosocius, meaning “nitrogen associate.” One species was even found in groundwater near Bremen, Germany, highlighting their adaptability.
A Surprising Connection to Oxygen
Further research revealed another unexpected trait. While the originally discovered symbiont only respired nitrate, the new species had an enzyme that allowed them to also breathe oxygen. This explains why they can survive in environments that have some oxygen.
Why This Matters
This discovery has big implications for science and the environment. These microbes play a role in the nitrogen cycle, potentially removing pollutants like nitrogen oxides but also producing greenhouse gases like nitrous oxide. Understanding them better could help scientists predict and manage these environmental impacts.
Microbial Marvels: Symbiosis in Action
Nitrate-breathing microbes aren’t the only symbiotic stars. Here are other jaw-dropping partnerships:
1. Fungi: Silent Nitrogen Heroes
Fungi like Fusarium oxysporum partner with plants, exchanging carbon for nitrogen. They dominate the later stages of the nitrogen cycle, breaking down nitrates and reducing N₂O emissions using genes like P450nor .
2. Legumes & Bacteria: Nature’s Fertilizer Factories
Rhizobia bacteria nestle in legume roots (e.g., soybeans, peas), converting atmospheric nitrogen into plant-friendly ammonia. In return, plants supply sugars—a win-win for sustainable agriculture .
3. Gutless Worms & Sulfur-Savvy Bacteria
The marine worm Olavius algarvensis lacks a mouth and gut. Instead, it relies on sulfur-oxidizing bacteria living inside it to generate nutrients from toxic sulfides, recycling waste in a zero-waste loop .
4. Squid & Glowing Bacteria
The bobtail squid harbors Aliivibrio fischeri in its light organ. Using quorum sensing, the bacteria glow only at high densities, camouflaging the squid from predators .
The Marvels of Microbial Life
Beyond their ecological impact, these microbes offer a glimpse into the incredible adaptability of life. Protists (single-celled organisms like ciliates) are known for their ability to form partnerships with bacteria, leading to astonishing metabolic innovations. These discoveries also help scientists understand how eukaryotic (complex) cells evolved over time.
As research continues, we may uncover even more about these fascinating microbes and their hidden roles in ecosystems worldwide. Who knows what other microscopic marvels are waiting to be discovered?
Source: SciTech daily
