Hiro Imachi
@hiro-imachi.bsky.social
190 followers 94 following 20 posts
Microbe Hunter
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hiro-imachi.bsky.social
Would you like to work with us?
At JAMSTEC, we are recruiting postdoctoral researchers through the Young Research Fellow program.
This program allows fellows to independently pursue their own research projects.
www.jamstec.go.jp/recruit/e/jy...
JAMSTEC Young Research Fellow (JYRF) | JAMSTEC - JAPAN AGENCY FOR MARINE-EARTH SCIENCE AND TECHNOLOGY
JAMSTEC Young Research Fellow (JYRF)
www.jamstec.go.jp
Reposted by Hiro Imachi
ryoharada.bsky.social
New paper out!
We discovered a tiny archaeon with the smallest known archaeal genome — only 238 kbp!
Candidatus Sukunaarchaeum mirabile has almost no recognizable metabolic pathways and may rely heavily on a host to survive.
It also represents a novel, deep-branching lineage in the archaeal tree.
biorxiv-evobio.bsky.social
A cellular entity retaining only its replicative core: Hidden archaeal lineage with an ultra-reduced genome https://www.biorxiv.org/content/10.1101/2025.05.02.651781v1
Reposted by Hiro Imachi
hiro-imachi.bsky.social
HC1 is capable of tolerating low oxygen levels. In contrast, SC1 appears unable to do so, likely because it lacks genes related to oxygen metabolism. We believe this difference stems from the fact that SC1 was cultured from the beginning under strictly anaerobic conditions with reducing agents.
hiro-imachi.bsky.social
Thank you again for introducing our work!
I'd greatly appreciate it if you could correct one point in episode #4.
Reposted by Hiro Imachi
hiro-imachi.bsky.social
Lokiarchaeia is MBG-B, not MBG-D.
hiro-imachi.bsky.social
MK-D1 was isolated from marine sediment collected from a methane seep approximately 2500 meters deep in the Nankai Trough off the Kii Peninsula in Japan, not from a drill core sample collected off the Shimokita Peninsula.
hiro-imachi.bsky.social
Thank you so much for introducing our work!
Could you kindly make the following corrections to story #1?
hiro-imachi.bsky.social
The genomic information for our strains, which belong to the ‘Hodarchaeales', has been released. Due to a large-scale server replacement at DDBJ (DNA Database of Japan), the release has been delayed.
Reposted by Hiro Imachi
masarunobu.bsky.social
New isolates from eukaryote's closest archaeal relative: ‘Hodarchaeales’!! Syntrophic microaerotolerant peptide-degrading anaerobic archaea w/ simple cell structure & protrusions. Features conserved across the phylum provide new insight into our ancestor’s biology!
www.biorxiv.org/content/10.1...
Eukaryotes' closest relatives are internally simple syntrophic archaea
Eukaryotes are theorized to have originated from an archaeal phylum Promethearchaeota (formerly 'Asgard' archaea)1,2. The first cultured representatives revealed valuable insight3,4 but are distantly ...
www.biorxiv.org
hiro-imachi.bsky.social
Thank you for the kind comments!
hiro-imachi.bsky.social
Thank you for the kind comment!
hiro-imachi.bsky.social
Isolated in just 3 years! (previously, 12 years). We obtained two strains from 'Hodarchaeales', proposed to be closest to our archaeal ancestor. Our analysis suggests the ancestor was an anaerobic, syntrophic, peptidotrophic, archaeon with a simple intracellular structure and possible aerotolerance.
Eukaryotes' closest relatives are internally simple syntrophic archaea
Eukaryotes are theorized to have originated from an archaeal phylum Promethearchaeota (formerly 'Asgard' archaea)1,2. The first cultured representatives revealed valuable insight3,4 but are distantly ...
www.biorxiv.org
hiro-imachi.bsky.social
Methanol syntrophy!
A new form of syntrophic relationship between bacteria and archaea in the underground.

Congratulations, Huang-san and Nobu!
masarunobu.bsky.social
Underground happy hour?
Excited to share our discovery of a new symbiosis between subsurface bacteria and archaea bridged by syntrophic transfer of the smallest alcohol—methanol! @nature.com

Work led by a former student Huang Yan, congratulations!
rdcu.be/d7W2s
Methanol transfer supports metabolic syntrophy between bacteria and archaea
Nature - Zhaonella formicivorans produces methanol, for a novel syntrophic interaction, without requiring methylated compounds as an input.
rdcu.be
hiro-imachi.bsky.social
Why did an engineer become a researcher in biological evolution? My esteemed research partner, colleague, and friend, Masaru K. Nobu, is sharing some side stories about strain MK-D1 research.
www.nature.com/articles/s41...
Engineering history with Asgard archaea of the kingdom Promethearchaeati - Nature Microbiology
Multiple histories converge in Masaru Nobu’s story of culturing an archaeon closely related to us eukaryotes.
www.nature.com
hiro-imachi.bsky.social
I’m currently trying to isolate uncultivated deep-sea sedimentary microorganisms using the reactor enrichment as an inoculum. If you happen to have time, I would be honored if you could take a look at a paper I published two years ago, where I provide more details about the reactor.
hiro-imachi.bsky.social
I’m truly grateful for the warm welcome—thank you so much!

I apologize for the confusion. To clarify, I’ve been supplying 0.57L of anaerobic medium to the reactor each day, which brings the total to 3733L so far. Also, my reactor will be turning 18 on December 28th.