An important scientific problem in the field of hydrogen biomedicine is that the action mechanism of hydrogen is not clear, but in the field of bacterial metabolism, the physiological role of hydrogen is very clear. The in-depth study of these action phenotypes is conducive to finding the biochemical basis of hydrogen action. Understanding these effects has a very important reference value for analyzing the action mechanism of hydrogen in human and other animal plant cells. Hydrogen medicine scholars should be very interested in this research and hope that more microbial metabolism researchers can have closer exchanges and cooperation with hydrogen medicine researchers, which may become an important gap to break the research dilemma of hydrogen medicine.

This content has two values: one is the research on soil hydrogen, and the other is the relationship between hydrogen and life evolution. Hydrogen plays an important role in the whole biological world. For the earth's ecosystem, especially the microbial community, hydrogen may be a bioenergy maintenance system. In the harsh living environment of energy shortage, with hydrogen from the atmospheric environment, these microorganisms have the basic conditions for sustainable survival. Some microbial species, which can survive in extremely harsh environments, may benefit from the electrons contributed by hydrogen, although the energy is limited. Without hydrogen, some microbial species may not survive. Without hydrogen, the ancestors of complex life may not be able to maintain species complexity. It will be difficult for the earth to evolve single-cell eukaryotic life, let alone the emergence of plants and humans. If you want to thank an element that gave us life, non hydrogen! Because the evolution of life on earth is inseparable from the care of hydrogen.

There are two basic stages in the origin and evolution of life, one is the evolution from inorganic matter to organic matter, and the other is the evolution of life from low level to high level. Hydrogen plays an absolutely important role in various hypotheses of life evolution, because it is indispensable in the evolution of organic matter, the origin of life and the evolution of complex cells.

The earth's early atmosphere was rich in reducing gases, such as hydrogen, carbon monoxide and methane. These gases are also the environmental conditions in which many life originated. Hydrogen is ubiquitous, and its activation energy demand is very low. It is very easy to become hydrogen atoms and react with other substances. The most common chemical reaction is hydrogen to reduce other oxidation substrates, such as oxygen. This redox reaction can release chemical energy and provide energy for life processes.

More importantly, hydrogen molecules have strong diffusion ability, which provides conditions for hydrogen as the first electron donor of life (hydrogen language: oxygen is the only final electron acceptor of aerobic biological cells), and can provide energy for the generation of mitochondrial ion gradient. Proton gradient is the premise for cells to synthesize ATP.

According to the hypothesis of life origin of iron sulfur center, NiFe / FeS active center is similar to hydrogenase active site and can catalyze the conversion of hydrogen into protons and electrons. This process may have evolved 1 billion years ago, leading to the earliest microbiota of hydrogen production and hydrogen consumption. In many niches, hydrogen concentration may represent an environmental selection pressure. Today, the microbial community still maintains this ancient metabolic model, such as Escherichia coli, verruca and Helicobacter pylori.

Hydrogenases are well represented in the tree of life because they are found in thousands of genomes in more than 30 phyla (Fig. 1-3). Both human and plant genes contain this gene, and the estimated number is far more than 30 phyla（ Cell biology was divided into seven kingdoms by conservative method: Animal Kingdom, plant kingdom, fungi Kingdom, protozoa Kingdom, color algae Kingdom, bacteria Kingdom and archaea kingdom. At present, it can be divided into 117 phyla: 32 in animal kingdom, 8 in plant kingdom, 7 in fungal kingdom, 10 in protozoa, 13 in color algae Kingdom, 29 in bacterial kingdom, 2 in archaea and 16 in virus kingdom. There are many organisms that have not yet been classified into any phylum.)

Hydrogenase supports autotrophic and mixotrophic lifestyles in a variety of ecosystems, including soil, aquatic and animal related niches. Niche, also known as ecological niche, represents the minimum habitat threshold necessary for the survival of each organism in the ecosystem. Soil microorganism mainly refers to the general name of bacteria, fungi, actinomycetes and algae living in soil. It is an indispensable part of soil. These tiny microorganisms invisible to the naked eye are not only the core of soil biological fertility, but also an important "regulator" of soil life.

The growth of soil microorganisms is often limited by the lack of carbon source and nutrients. As long as it does not affect survival, even undernourished microorganisms can grow rapidly. Hydrogen is ubiquitous in the environment, only needs low activation energy, and is easy to penetrate into microbial cells. The prevalence of hydrogen is mainly due to its high penetration ability to materials, abiotic hydrogen generation in the earth's mantle and hydrogen production through biological fermentation, nitrogen fixation and other processes. In most ecosystems, hydrogen can reduce a variety of oxidants. Hydrogen can provide rapid energy supplement and help microorganisms overcome short-term or long-term starvation survival interval. Someone calculated this minimum energy demand from the perspective of thermodynamics and bioenergy.