Scientists at the Institute of Chemical Biology and Fundamental Medicine SB RAS and Novosibirsk State University conducted a scientific review of the diversity of soil microorganisms that mineralize phosphates. The researchers studied the biochemical and molecular biological mechanisms of this process, as well as assessed the potential role of microorganisms as natural biofertilizers in crop production. The results of their research are presented in a special article for the special issue “Plant Growth Promoting Bacteria” of “Plants” magazine.
Sergey Sedykh, Ph.D., NSU’s V. Zelman Institute for Medicine and Psychology Senior Lecturer discussed the article,
This article was written as part of the All-Russian Atlas of Soil Microorganisms project. The grant supporting the project requires that "citizen scientists" including schoolchildren and their mentors, school teachers, and additional education organizations participate in the research. The scientist’s assistants, together with mentors, collect soil samples, conduct their primary screening (determine pH and other physico-chemical characteristics), and identify microorganisms that are useful for plant growth in special environments. Soil and microbe samples are given to the scientists. Since the project started in 2019, several dozen bacteria that improve plant growth that were collected with the participation of children have appeared in the ICBFM SB RAS collection. This year we have to collect ten thousand samples of soil and microorganisms, put them in the collection and on the map.
Soil phosphate-solubilizing bacteria mobilize phosphate in several ways. Some secrete organic acids such as citric acid, a component of the Krebs cycle, releasing inorganic phosphates, for example in rocks and volcanic ash. If the ashes are treated with these bacteria, an excellent fertilizer is obtained that is especially in demand wh ere there is a lot of volcanic material such as in Kamchatka. According to the primary data from Kamchatka farmers, the use of volcanic ash for fertilizing plants allows them to increase the potato yield and other crops by 30%.
The second type of phosphate-solubilizing bacteria releases enzymes that cleave organic phosphates. This, for example, makes it possible to extract phosphates from phytin, a complex organic preparation of phosphorus containing a mixture of calcium and magnesium salts of various inositol-phosphoric acids. This is abundant in soil, humus, and mold. The third type of bacteria that is useful for agriculture synthesizes siderophores, special organic compounds secreted by bacterial cells for self-sufficiency in vital iron.
The researchers also found that phosphate utilization efficiency can be increased by infecting seeds with a solution of bacterial preparations. According to various estimates, the appropriate use of microorganisms will reduce the amount of fertilizers by 40-80% and obtain the same yield. You can also use the same amount of fertilizer and have a significantly larger yield, or eliminate the use of fertilizers completely and get more organic products if, thanks to the use of nitrogen-fixing bacteria, you also eliminate nitrogen fertilizers. According to scientists, producing microorganisms that are useful in agriculture can be done at a comparatively low cost, since bacteria, unlike mineral fertilizers, are able to multiply.
Dr. Sedykh emphasized that in addition to scientific interest, this study can help farmers in practice. The identified cultures of microorganisms that interact with organic and inorganic phosphates and release certain acids should be checked by specialists in field experiments on different crops and in different regions. That is why the next task that scientists will be engaged in is the search for beneficial bacteria in samples sent to the ICBFM SB RAS by “citizen scientists”.
The material is based on a news article published by Science in Siberia (in Russian).
