Study On Multi-factor Regulation Of Microbial Induced Calcium Carbonate Precipitation

Biomimetic synthesis has always been the focus of attention among materials scientists,chemists and biologists.It has been found that a small amount of organic matrix existing in natural materials such as shells is the key to the formation of a unique stacking hexagonal bridge.When calcium carbonate crystals are self-assembled with such special structures,Organic matter filled around hexagonal calcium carbonate particles acts as biological cement,giving it excellent hardness and toughness.However,the growth of natural materials is slow.In order to synthesize materials with similar structure and crystal morphology rapidly,the biosynthetic method of microbial-induced calcium carbonate was introduced into bio-mimetic system in this paper.In order to simulate the special morphology and crystal type of natural materials,the microstructure and crystal types of calcium carbonate were observed by regulating the bio-mineralization process of calcium carbonate.In this study,the effects of organic calcium source and inorganic calcium source on mineralization were systematically compared,and one of the calcium sources was selected as the follow-up study.Then,from the factors that regulate bio-mineralization in vitro reported in the literature,we select the organic matrix or additive with special function,and study the use of organic matrix or additive by microorganism.In the process of bio-mineralization induced by microorganisms to form calcium carbonate,the nucleation,assembly and growth of inorganic minerals are controlled by bio-mimetic synthesis of bio-mineralized compounds with special morphology.The main contents of this study are as follows:?The regulation of inorganic ions on microbial mineralization was studied by Mg²⁺.It was found that with the decrease of Ca/Mg molar ratio,the morphology of crystals changed from irregularly shaped intermediate state and spherical vaterite to clusters.The needle-like or lamellar aragonite crystal,the larger the concentration of Mg²⁺ions,the easier it is to form pure aragonite calcium carbonate.?The agarose gel was used as a representative to study the regulation of microbial mineralization in the gel system.It was found that calcite-type calcium carbonate was produced under the control of agarose gel,which did not have a specific shape,and the particles were uneven and the size was large.?Taking sodium alginate and Ca²⁺to form a unique gel bead,the regulation of microbial mineralization by calcium source gel beads was studied.It was found that the calcium carbonate formed was calcite type,and the microstructure of calcium carbonate was irregular polygon and cube.shape.?The study of soluble starch as an organic template for the regulation of microbial mineralization process,found that the calcium carbonate produced is calcite type and vaterite type.The crystal form is lamellar or clustered.?Studied the regulation of microbial mineralization by egg white and egg yolk as organic templates.It was found that spherical calcite and aragonite calcium carbonate with diameter between 1.22?m and 2.80?m were produced under the control of egg white.Under the control of egg yolk,a spherical shape and a spindle shape are formed,and the diameter is about 4.99?m to 16.1?m between calcite type and vaterite type calcium carbonate.?Studied the regulation of microbial mineralization in water-soluble organic matter in pearls and shells.It was found that irregularly shaped calcite and vaterite-type calcium carbonate were formed under the control of WSM in pearls.Layers were produced under the control of shell WSM.Shape,clustered calcite and aragonite calcium carbonate.The greater the concentration of organic matter,the larger the size of the calcium carbonate particles.?The regulation of microbial protein-silk fibroin on microbial mineralization was studied.It was found that silk fibroin induced the formation of vaterite-type calcium carbonate.The higher the protein concentration,the greater the effect on the crystal form of calcium carbonate.To sum up:different organic matrices or additives have different effects on the microbial mineralization process.By using different organic matrices or additives,a wide variety of calcium carbonate materials can be obtained,thus providing a theoretical reference for the development of new biomaterials.