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▎Edited by WuXi AppTec Content Team In the vast ocean, in addition to those marine creatures visible to the naked eye, there is also a huge microbial empire
.
This invisible group produces at least half of the world's oxygen, driving the continuous cycle of carbon and nitrogen.
.
.
In this complex network, ammonia-oxidizing archaea are an integral part
.
These archaea account for 30% of marine microplankton and are an important link in the marine nitrogen cycle
.
They use oxygen to convert ammonia into nitrite, the most important source of inorganic nitrogen in the ocean
.
Simply put, this is the equation: NH3 +1.
5O2 → NO2− + H2O + H+
.
However, discoveries in recent years have made the survival mode of these ammonia-oxidizing archaea more confusing
.
According to the above reaction, the survival of these archaea requires sufficient oxygen
.
However, scientists have found a large number of ammonia-oxidizing archaea in the most hypoxic "minimum oxygen zone" (200-1000 meters deep) in the ocean
.
Be aware that the oxygen concentration here can be undetectably low
.
So how do they manage to survive here? In a new study published in Science, scientists from the University of Southern Denmark have revealed a surprising discovery: An ammonia-oxidizing archaea can synthesize oxygen by itself in a dark, oxygen-deficient environment for the ammonia oxidation reaction
.
The discovery promises to unravel the mystery of the survival of these microbes in anoxic seawater and change our understanding of the nitrogen cycle
.
In this study, in order to reproduce the survival state of ammonia-oxidizing archaea in the smallest oxygen-containing zone of the ocean, the research team collected an ammonia-oxidizing archaea called SCM1
.
They cultivated these archaea in a solution that simulated anoxic seawater, and monitored changes in the oxygen concentration in the solution with the help of sophisticated instruments - the instrument can measure with an accuracy of 1 nanomolar per liter, so slight fluctuations in oxygen concentration can be studied.
catcher
.
"We wanted to see what happens when oxygen is depleted, as they move from oxygen-rich seawater into oxygen-poor seawater
.
Can they survive?" said Professor Beate Kraft, who led the study
.
▲Professor Beate Kraft led the research (Image source: Jacob Fredegaard Hansen, SDU) In the culture medium, as the ammonia oxidation reaction proceeds, the oxygen is gradually reduced
.
When the oxygen runs out, the magic happens: after just a few minutes, the oxygen concentration rises again, finally reaching a concentration of 100-200 nanomoles per liter
.
Could it be that these archaea produced oxygen? Since then, more than two years of continuous experiments have shown that the increase in oxygen is not accidental
.
After excluding possible pollution sources and possible reaction processes such as the decomposition of hydrogen peroxide, the research team can determine that the ammonia-oxidizing archaea produced oxygen while utilizing oxygen
.
This oxygen is not enough to change the oxygen concentration of the earth, but it allows them to survive in the dark and oxygen-poor environment
.
"If they produce more oxygen than they need, the excess oxygen is quickly used by nearby organisms, so it never leaves the ocean
,
" explains Prof Kraft
.
So how did these archaea produce oxygen? Speaking of oxygen producers on Earth, we think of photosynthetic plants, algae, and cyanobacteria
.
Previous research has identified a small number of microbes that can produce oxygen in the dark, but their species and geographic range are very limited
.
In contrast, ammonia-oxidizing archaea, an important component of the marine microbial world, produce oxygen differently than all previous organisms
.
At present, the research team has not confirmed the specific mechanism by which they generate oxygen, but they have speculated on the possible mechanism based on the research: As the final product of the ammonia oxidation process, which is also the starting point of the oxygen production reaction, nitrite is reduced to nitric oxide by reductase.
.
Subsequently, nitric oxide undergoes a disproportionation reaction to form oxygen and nitrous oxide, respectively, and the latter is further reduced to nitrogen
.
▲The basic process of ammonia oxidation reaction (Image source: Reference [2]) So far, this result provides a possible explanation for the survival of ammonia-oxidizing archaea in anoxic seawater, and reveals that they may be responsible for nitrogen elements in the ocean loss plays an important role
.
The study may also provide clues to the evolution of Earth's nitrogen cycle
.
▲ The oxygen production reaction speculated by the research team (Image source: Reference [2]) "If this kind of survival exists widely in the ocean, it will make us rethink the ocean nitrogen cycle
.
" Professor Kraft said
.
Next, the research team plans to validate their findings in the lab in oceans around the world
.
Perhaps, these invisible tiny creatures can really shake the earth's extremely important element cycle
.
References: [1] Beate Kraft et al.
, Oxygen and nitrogen production by an ammonia-oxidizing archaeon.
Science (2022) Willm Martens-Habbena and Wei Qin , Archaeal nitrification without oxygen.
Science (2022) Microbes produce oxygen in the dark.
Retrieved Jan.
6, 2022 from https:// news-releases/939090
.
This invisible group produces at least half of the world's oxygen, driving the continuous cycle of carbon and nitrogen.
.
.
In this complex network, ammonia-oxidizing archaea are an integral part
.
These archaea account for 30% of marine microplankton and are an important link in the marine nitrogen cycle
.
They use oxygen to convert ammonia into nitrite, the most important source of inorganic nitrogen in the ocean
.
Simply put, this is the equation: NH3 +1.
5O2 → NO2− + H2O + H+
.
However, discoveries in recent years have made the survival mode of these ammonia-oxidizing archaea more confusing
.
According to the above reaction, the survival of these archaea requires sufficient oxygen
.
However, scientists have found a large number of ammonia-oxidizing archaea in the most hypoxic "minimum oxygen zone" (200-1000 meters deep) in the ocean
.
Be aware that the oxygen concentration here can be undetectably low
.
So how do they manage to survive here? In a new study published in Science, scientists from the University of Southern Denmark have revealed a surprising discovery: An ammonia-oxidizing archaea can synthesize oxygen by itself in a dark, oxygen-deficient environment for the ammonia oxidation reaction
.
The discovery promises to unravel the mystery of the survival of these microbes in anoxic seawater and change our understanding of the nitrogen cycle
.
In this study, in order to reproduce the survival state of ammonia-oxidizing archaea in the smallest oxygen-containing zone of the ocean, the research team collected an ammonia-oxidizing archaea called SCM1
.
They cultivated these archaea in a solution that simulated anoxic seawater, and monitored changes in the oxygen concentration in the solution with the help of sophisticated instruments - the instrument can measure with an accuracy of 1 nanomolar per liter, so slight fluctuations in oxygen concentration can be studied.
catcher
.
"We wanted to see what happens when oxygen is depleted, as they move from oxygen-rich seawater into oxygen-poor seawater
.
Can they survive?" said Professor Beate Kraft, who led the study
.
▲Professor Beate Kraft led the research (Image source: Jacob Fredegaard Hansen, SDU) In the culture medium, as the ammonia oxidation reaction proceeds, the oxygen is gradually reduced
.
When the oxygen runs out, the magic happens: after just a few minutes, the oxygen concentration rises again, finally reaching a concentration of 100-200 nanomoles per liter
.
Could it be that these archaea produced oxygen? Since then, more than two years of continuous experiments have shown that the increase in oxygen is not accidental
.
After excluding possible pollution sources and possible reaction processes such as the decomposition of hydrogen peroxide, the research team can determine that the ammonia-oxidizing archaea produced oxygen while utilizing oxygen
.
This oxygen is not enough to change the oxygen concentration of the earth, but it allows them to survive in the dark and oxygen-poor environment
.
"If they produce more oxygen than they need, the excess oxygen is quickly used by nearby organisms, so it never leaves the ocean
,
" explains Prof Kraft
.
So how did these archaea produce oxygen? Speaking of oxygen producers on Earth, we think of photosynthetic plants, algae, and cyanobacteria
.
Previous research has identified a small number of microbes that can produce oxygen in the dark, but their species and geographic range are very limited
.
In contrast, ammonia-oxidizing archaea, an important component of the marine microbial world, produce oxygen differently than all previous organisms
.
At present, the research team has not confirmed the specific mechanism by which they generate oxygen, but they have speculated on the possible mechanism based on the research: As the final product of the ammonia oxidation process, which is also the starting point of the oxygen production reaction, nitrite is reduced to nitric oxide by reductase.
.
Subsequently, nitric oxide undergoes a disproportionation reaction to form oxygen and nitrous oxide, respectively, and the latter is further reduced to nitrogen
.
▲The basic process of ammonia oxidation reaction (Image source: Reference [2]) So far, this result provides a possible explanation for the survival of ammonia-oxidizing archaea in anoxic seawater, and reveals that they may be responsible for nitrogen elements in the ocean loss plays an important role
.
The study may also provide clues to the evolution of Earth's nitrogen cycle
.
▲ The oxygen production reaction speculated by the research team (Image source: Reference [2]) "If this kind of survival exists widely in the ocean, it will make us rethink the ocean nitrogen cycle
.
" Professor Kraft said
.
Next, the research team plans to validate their findings in the lab in oceans around the world
.
Perhaps, these invisible tiny creatures can really shake the earth's extremely important element cycle
.
References: [1] Beate Kraft et al.
, Oxygen and nitrogen production by an ammonia-oxidizing archaeon.
Science (2022) Willm Martens-Habbena and Wei Qin , Archaeal nitrification without oxygen.
Science (2022) Microbes produce oxygen in the dark.
Retrieved Jan.
6, 2022 from https:// news-releases/939090
