Secrets found under the ice of Antarctica... Clues to the formation of giant iron ore deposits discovered

(Seoul = Yonhap News) Reporter Shin Seon-mi = A domestic research team discovered microorganisms and key genes that oxidize iron in seafloor sediments under the Antarctic Ice Shelf (a large layer of ice floating in the sea).

This research is evaluated as having found new clues about the process by which huge iron ore layers are created on Earth.

A research team involving Yonsei University, Sungkyunkwan University, and the Polar Research Institute analyzed metagenomes (sum of genome information of microbial communities) from seafloor sediments under the Larsen C Ice Shelf in Antarctica.

Sediments were collected from the seafloor at a depth of 324 m through research on the icebreaker Araon in 2013.

The researchers explained that the sedimentary layer from which samples were collected shows changes in the marine environment over the past 12,000 years, from the last ice age of the Quaternary Period of the Cenozoic Era to the present.

Through metagenome analysis, the research team discovered the bacterium Mariimomonas peroxidans (tentative name), which oxidizes iron in an environment where light and oxygen are limited.

In addition, a gene that produces a specific protein (Cys2) expected to be involved in iron oxidation was discovered in the genome sequence of this bacterium, and its function was experimentally identified.

The researchers explained the significance of the results of this study in that they provide clues about microbial metabolism and iron circulation during the 'Snowball Earth' period.

Scientists have explained the formation of the huge 'iron ore layer' created by the accumulation of iron and silicon as the result of photosynthetic bacterial activity, but this hypothesis had the limitation of not being able to explain the iron ore layer formation process on Earth at a time when ice covered the Earth.

Jaekyung Yoon, a research professor at Yonsei University and the first author of the research paper, said, "The result of this research is that we analyzed the Antarctic sedimentary layer containing over 10,000 years of records, reconstructed the environment and microbial ecosystem at that time, and linked it from genome restoration of key microorganisms to functional verification."

Professor Jihyeon Kim of Yonsei University, who led the research, said, “We expanded the existing perspective that explained the formation of iron mineral layers by focusing on photosynthetic bacteria.”

This research was conducted with support from the Ministry of Science and ICT and the National Research Foundation of Korea's individual research project (mid-level research/type 2), national research institute (NRL2.0) project, Ministry of Oceans and Fisheries marine microbiome-based ecological environment management technology development project, and Polar Research Institute's institution-specific project.

The research results were published today in the international academic journal 'Microbiome'.