Scientists report unusual find under Fukushima reactors

Researchers discovered unexpected microbial communities in the highly radioactive water beneath the Fukushima Daiichi nuclear power plant in Japan. Most surprisingly, these bacteria did not demonstrate significant genetic resistance to radiation, yet were still able to actively reproduce.

Popular Mechanics reports.

How did these microorganisms adapt to the radioactive environment?

After the 2011 tsunami caused a major accident at the Fukushima Daiichi nuclear power plant, Japan suspended all nuclear operations. Recently, however, the country restarted one of the surviving reactors, prompting biologists to analyze samples of microbes collected from the highly radioactive water in the torus chamber beneath the reactor building.

Contrary to expectations, the bacteria in the toroidal chamber did not have the "special enhanced" genetic mechanisms typically associated with resistance to ionizing radiation.

Logically, organisms in a nuclear catastrophe zone either die or evolve. Therefore, scientists expected to find microorganisms known for their tolerance of radiation, such as Deinococcus radiodurans and Methylobacterium radiotolerans. However, an analysis of genetic markers in the samples revealed something different.

The samples were found to be rich in Limnobacter and Brevirhabdus bacteria. These chemolithotrophic microorganisms obtain energy by oxidizing inorganic compounds, specifically manganese or sulfides, and they can convert sulfides into sulfates. Additionally, a few "iron oxidizers" from the genera Hoeflea and Sphinopyxis were found. These bacteria convert one form of iron to another to survive.

Despite the toxic level of ionizing radiation for many forms of life, these bacteria were able to thrive. The study's authors noted one possible factor that helped the microbes establish themselves: the mixture of emergency cooling water and seawater inside the toroidal chamber likely promoted the growth of biofilms on metal surfaces. Since these bacteria can oxidize and "eat" metals, scientists speculated that the mucous membrane of bacterial masses could serve as an additional barrier, partially protecting the bacteria from radiation.

Another detail that caught the researchers' attention is that many of the microorganisms found in the toroidal chamber are also found in the ocean. There are two possible explanations: the microorganisms either entered the station with tsunami waves or their marine adaptability helped them survive the conditions inside the damaged reactor.

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