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Higher animals and plants on the earth usually have certain laws of geographical differentiation, such as "the one side of water and soil raises one person" as the proverb often said, but for a long time due to the limitations of technical means, the geographical differentiation of soil microorganisms and its functional significance Not very clear.
Recently, the team of Jia Zhongjun of the Institute of Soil Science, Chinese Academy of Sciences and the team of He Yuanqiu discovered that there is an active ammonia-oxidizing archaea in acid soil (pH4.9), and the closest microorganism to the archaea comes from the alkaline environment (pH8.0). This study shows that the ammonia-oxidizing archaea has a strong adaptability to soil environmental variation, and its geographical differentiation is not completely consistent with higher organisms.
According to the environment in which they live, the known ammonia-oxidizing archaea can be divided into three categories. It mainly includes marine group 1.1a, soil group 1.1b and thermophilic group AOA. However, all the currently known 1.1b archaea in the soil group only grow under neutral and slightly alkaline conditions, the optimal pH is between 6.0-8.2, and almost do not play a role under acidic conditions, known as neutrophils Archaea. After a large amount of molecular screening work in the early stage, Dr. Wang Baozhan and doctoral student Zheng Yan conducted a functional diversity study on ammonia-oxidizing microorganisms in a typical acid red soil. Using the stable isotope 13C-tracer microbial nucleic acid DNA, it was found that the soil group 1.1b archaea assimilated a large amount of 13CO2 autotrophic growth, combined with high-throughput sequencing technology and dynamic monitoring of soil pH, indicating that the soil group 1.1b archaea dominated the acid soil Ammonia oxidation process. Further molecular phylogenetic analysis showed that the relationship between 1.1b archaea and acidophilic archaea in this acidic soil was as high as 99% (16S rRNA ribosomal gene).
Archaea are considered to be the "third form" of life and are significantly different from bacteria and higher organisms. The results show that: under the long-term environmental selection pressure, soil 1.1b archaea have significantly differentiated their physiological and metabolic functions, and their ability to adapt to acidic or alkaline environments has been significantly enhanced. Functional significance provides an important reference.
The research was supported by the National Natural Science Foundation of China Youth Science Foundation Project and has been published online by the American Society of Microbiology journal Applied and Environmental Microbiology.
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