Scientists have studied to reveal the molecular mechanism of interaction between soil minerals and microbes. The reporter recently learned from the Institute of Soil and Water Conservation, Chinese Academy of Sciences that the young researcher Fang Linchuan of the institute combined macroscopic adsorption experiments and isothermal titration of trace heat, X-ray absorption fine structure and other modern instrument analysis techniques At the molecular level, the interaction process and mechanism of the extracellular polymer (EPS) secreted by bacteria in the soil and goethite are revealed. This study has important theoretical and practical significance for revealing the nature of soil, rationally regulating soil biological activity, elucidating bacterial adhesion, biofilm formation and functional mechanism, and migration and distribution of pollutants.
It is understood that in natural soil, 80% to 90% of microorganisms adhere to the surface of various minerals or mineral-organic complexes, forming a single microcolonies or biofilms. Before forming a biofilm, the extracellular polymer secreted by bacteria first forms a "conditional film" on the solid surface of the soil to regulate the adhesion and migration of bacteria, which in turn affects the structure and function of the biofilm.
Fang Linchuan's research found that the phosphorus-containing groups in proteins, nucleic acids and other macromolecules secreted by bacteria in the extracellular complex coordinate with the hydroxyl groups on the goethite surface to form an inner ring complex, and the adsorption product structure and system pH have Closely related. At low pH (pH 3.0), the phosphate group has only one deprotonated oxyanion directly combined with the FeOH1 / 2- group on the goethite surface to form a monodentate complex; while at high pH (pH Is 9.0), two oxyanions in the phosphate group combine with two FeOH1 / 2- groups on the goethite surface to form a bidentate complex. At the same time, when the pH of the system changes from low to high (3.0-9.0), the configuration of the adsorption product transitions from single-base coordination to double-base coordination, thus revealing that the pH of the system affects the dissociation of phosphate protons in EPS-P in solution and Association is an important cause of changes in the configuration of adsorption products.
This result indicates that there may be some molecular recognition mechanism in the process of the interaction between microorganisms and minerals in the soil. The formation of PO-Fe bonds between the extracellular polymer secreted by bacteria and goethite has a role in bacterial adhesion and biofilm formation. Important regulatory role.
Related results have been published in the international academic journal "Water Research".
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