It is the first time to identify the existence of "electric synthesis" microorganisms living by electric energy like SF, a third synthesis following photosynthesis and chemical synthesis

The joint research team of the RIKEN University of Tokyo University announced that it succeeded in identifying living microorganisms for the first time by directly using electric energy and successfully detecting their metabolic reactions. As a method of producing nutrients from carbon dioxide, "photosynthesis" that synthesizes starch from carbon dioxide with sunlight as energy, and "chemical synthesis" that uses energy of chemical substances such as hydrogen and sulfur in an environment where sunlight does not reach Although it was confirmed that two microorganisms capable of "electrosynthesis" are newly discovered by this discovery, a part of its metabolic mechanism has been clarified.

First time to identify microorganisms living by electricity | RIKEN
http://www.riken.jp/pr/press/2015/20150925_1/

KAKEN - Proof of presence of deep sea hydrothermal power generation and electrosynthetic microbial community (24244091)
https://kaken.nii.ac.jp/d/p/24244091.ja.html

Biochemical catalyst research team | RIKEN
http://www.riken.jp/research/labs/csrs/biofunct_catal/

First of all, as a preliminary step of this discovery, it has been discovered that there is abundant "rocks that pass electricity very well" in the deep sea hydrothermal environment where sunlight does not reach in 2010. This rock It was discovered that "current is generated" by contact with hot water blowing out from the bottom of the sea as a catalyst. Based on this premise, the hypothesis was made that "Are some of the organisms inhabiting the ocean floor living by using electricity as the third energy to replace light and chemical substances?" And this discovery also Studies to become and will be done.

As a result of the research, we cultured the cells in an environment where iron ion is not included and Acidithiobacillus ferrooxidans (A.ferrooxidans) which is a type of iron oxidizing bacteria utilizing iron ions as energy, "electricity alone is the energy source" Confirmation of cell proliferation as a result. I found out that the cell has the ability to extract NADH by extracting electrons from the electrode outside the body and have the ability to synthesize organic matter from carbon dioxide via Rubisco protein.

This is a microscopic image of A.ferrooxidans which is a microorganism that produces nutrients using electric energy. "Electric synthesis" realizing carbon dioxide to make organic matter using electric energy.


Moreover, it is also confirmed that one type of iron oxidizing bacteria has the ability to raise the potential difference as small as 0.3 V to 1 V or more, so that very weak electric energy can be used.

What this means is that at 0.3 V it is impossible to produce organic matter from carbon dioxide, but by using a branched electron transporting path extending from the outer membrane to the inner membrane as a "boosting circuit", it is increased to 1.14 V and the potential difference It is said that it is "an electrosynthesis organism" that lives by utilizing.

The following figure shows the metabolic circuit known at the present time of electric synthesis. By utilizing the branched electron transfer system present in the cell as a booster circuit, it raises the potential difference of only 0.3 V to 1.14 V, and creates organic matter from carbon dioxide.


Based on the results of this study, we demonstrate that the use of electricity as an energy source reveals the existence of microorganisms that can grow, and at the same time it shows that electricity is the third energy supporting the food chain on Earth following light and chemicals It is led to the fact that there is an "ecological ecosystem" that is a biosphere dependent on electricity in the deep ocean, and it is expected to become an important knowledge.

In addition, the existence of "electrosynthetic microorganisms" living with very small electric power is to provide new knowledge from the viewpoint of utilization of micro electric power.