Examining electron transport shuttles in microorganisms

The Swiss Federal Institute of Aquatic Science and Technology.

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Every living thing needs energy. This is also true of the organisms. In other words, food and organic compounds are the main sources of energy in the cells. The electrons are released and the microorganisms need to get rid of them. The electrons can be transported to minerals outside of the cells if oxygen isn't present.

Reduction rates can vary a lot.

Iron oxides play a major role as acceptors of the released electrons. How do the electrons get from the cells to the iron oxides outside the cells? The process of transporting two electrons from the cell surface to the iron oxides can be done by the microorganisms. There are two electrons from the taxi that can reduce iron in oxides to its divalent form. The taxi is able to carry more electrons.

The EES have been known for a long time. It has never been clear why their efficiency is dependent on their structure and the environment, and why the speed of iron oxide reduction varies by several orders of magnitude. Attempts to explain the huge efficiency differences on the basis of known parameters have failed until now.

It is necessary to consider the electrons individually.

The study shows how efficiency differences can be explained by a single relationship. The average energy of the two transported electrons was not looked at in the study, but at the individual energy level of each electron.

Thomas Hofstetter says that the transfer of the first electron from the EES to the iron oxide is less efficient than the transfer of the second electron. The iron reduction rate is determined by the energy difference between the first electron transferred from the EES to the iron oxide.

It is possible to explain the efficiency differences between various EES, even across a sizeable pH range, as well as between two different iron oxides, using this concept. The first electron is very reluctant to leave the EES taxi, but it is pushed out from the back seat, so to speak, by the second electron.

UV light makes electron transfer visible.

To arrive at their findings, the authors of the study devised their own experiments and collected the data from previous studies. The researchers used natural and synthetic EES in their experiments in the Eawag and the ETH laboratories. The rate of electron transfer from the EES to the iron oxide can be seen with UV light. The light is absorbed differently by the EES if they are starting with or without the two electrons.

It's tiny but crucial.

The study describes a small step in the process of respiration, but it is critical to many processes. EES can be understood at a generic level, making comparisons easier between studies and systems. This paper is a must-read for anyone working with decaying organisms. This step is relevant for the understanding of global biogeochemical processes, for example the breakdown of organic substances in the thaw of the arctic soils, a process in which enormous quantities of climate-critical CO2 are released.

The rate of iron oxide reduction by extracellular electron shuttles is controlled by thermodynamic controls. There is a book titled "10.1073/pnas.2115629119."

The National Academy of Sciences has a journal.

The Swiss Federal Institute of Aquatic Science and Technology is located in Lausanne.

Examining electron transport shuttles in microorganisms was retrieved fromphys.org on January 12.

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