Escherichia coli coated calcium carbonate composite material powder and block and preparation method thereof

Abstract

The invention discloses Escherichia coli coated calcium carbonate composite material powder, a block and a preparation method thereof. The preparation method comprises the following steps: mixing and stirring natural escherichia coli expressing GFP and a buffer solution containing calcium ions to obtain a suspension; dropwise adding an aqueous solution containing carbonate ions into the suspension, and centrifuging, washing and drying after dropwise adding to obtain Escherichia coli coated calcium carbonate composite material powder. According to the preparation method, natural escherichia coli expressing GFP is effectively combined with calcium ions to inhibit crystal transformation, rapid centrifugal washing is carried out after titration is completed, vaterite powder with a stable and single crystal form is successfully prepared, and a composite material block is prepared through a cold sintering process. The operation method is simple, the cost is low, the method is suitable for large-scale production, and a new research thought is provided for preparing the large-size heterogeneous composite material which can achieve synergistic improvement of strength and toughness and has a macroscopic geometrical shape.

Description

Technical Field

[0001] The present invention relates to the technical field of bionic composite materials, and particularly to a composite powder and block of Escherichia coli-coated calcium carbonate and a preparation method thereof. Background Art

[0002] With the development of history and the progress of the times, the requirements for structural materials in various engineering technology fields have become increasingly high, such as low density, high strength, high hardness, and toughness. However, among these properties, strength and toughness are usually mutually exclusive. The most representative ceramic materials are widely used in engineering structural materials, but their high density and low toughness are greatly restricted. Therefore, lightweight natural biological structural materials have received extensive attention from researchers. In particular, biological materials such as bones, teeth, and shells, although composed of brittle minerals and organic polymers or nanoparticles, have mechanical properties of high strength and toughness. However, most of the currently prepared series of novel shell-like reinforced materials are relatively small in size, making it difficult to achieve industrial production, and most bionic structural materials still do not satisfactorily achieve a variety of excellent properties. Therefore, inspired by the growth process of the heterogeneous structure of biological materials, it is expected to prepare bionic composite materials with large size, synergistically enhanced mechanical properties, and functional characteristics.

[0003] In biological mineral materials, the inorganic mineral part mainly includes crystals formed by common compounds such as calcium carbonate, calcium phosphate, and silicon dioxide. Among them, calcium carbonate includes three crystal forms, and vaterite is the most unstable crystal form. However, due to the microscopic morphology of vaterite being spherical particles clustered by small particles of about 50 nm, it is beneficial for subsequent research on the preparation of blocks. However, in the relevant research carried out in China at present, in the absence of additives to inhibit crystal transformation, the pure vaterite particles prepared by the coprecipitation method react with calcium ions and carbonate ions at low concentrations (10 - 20 mM), which is not conducive to the large-scale preparation of vaterite powder; the calcium carbonate prepared by reacting with high-concentration calcium ions (≥50 mM) and carbonate usually includes two crystal forms, vaterite and calcite, and the purity is poor.

[0004] Therefore, it is urgent to improve the existing preparation method to achieve the large-scale preparation of pure vaterite-type calcium carbonate and obtain heterogeneous composite materials with macroscopic geometric shapes and synergistically achieving high strength and high toughness. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, and propose a composite powder and block of Escherichia coli-coated calcium carbonate and a preparation method thereof, so as to solve the technical problems that the pure vaterite-type calcium carbonate powder in the prior art is often unable to be prepared on a large scale due to the use of low concentrations, and the existing bionic structural materials cannot achieve the synergistic improvement of large size, high strength, and high toughness.

[0006] In a first aspect, the present invention provides a method for preparing a powder of Escherichia coli-coated calcium carbonate composite material, comprising the following steps: Providing a buffer solution containing calcium ions, an aqueous solution containing carbonate ions, and natural Escherichia coli that has expressed GFP; Mixing and stirring the natural Escherichia coli that has expressed GFP and the buffer solution containing calcium ions to obtain a suspension; Dropping the aqueous solution containing carbonate ions into the suspension, and after the dropping is completed, centrifuging, washing, and drying to obtain a powder of Escherichia coli-coated calcium carbonate composite material.

[0007] In a second aspect, the present invention provides a powder of Escherichia coli-coated calcium carbonate composite material, which is obtained by the method for preparing a powder of Escherichia coli-coated calcium carbonate composite material provided in the first aspect of the present invention.

[0008] In a third aspect, the present invention provides a method for preparing a block of Escherichia coli-coated calcium carbonate composite material, comprising the following steps: Obtaining a block of Escherichia coli-coated calcium carbonate composite material from the powder of Escherichia coli-coated calcium carbonate composite material through a cold sintering process; wherein, the sintering temperature is 37 - 250 °C, the heat preservation time is 2 - 3 h, the heating rate is 5 - 10 °C / min, and the applied pressure is 500 - 700 MPa.

[0009] In a fourth aspect, the present invention provides a block of Escherichia coli-coated calcium carbonate composite material, which is obtained by the method for preparing a block of Escherichia coli-coated calcium carbonate composite material provided in the third aspect of the present invention.

[0010] Compared with the prior art, the beneficial effects of the present invention include: The present invention effectively blocks the strong interaction generated by the effective combination of natural Escherichia coli that has expressed GFP and calcium ions, thereby inhibiting the crystal form transformation, and quickly centrifuging and washing after the carbonate titration is completed, successfully preparing a vaterite powder with stable and single crystal form, and then preparing a composite material block with fluorescence characteristics through a cold sintering process. The operation method of the present invention is simple, low in cost, suitable for large-scale production, and wide in application range, providing a new research idea for preparing a large-size heterogeneous composite material that can achieve the synergistic improvement of strength and toughness and has a macroscopic geometric shape. Description of the Drawings

[0011] Figure 1 is the X-ray electron diffraction pattern of the CaCO 3 @E. coli powder prepared under different theoretical concentrations of calcium ions and carbonate ions after mixing in Examples 1 - 4 of the present invention; Figure 2 This is the X-ray electron diffraction pattern of the CaCO 3 @E. coli powder prepared in Comparative Example 1 of the present invention; Figure 3 These are the X-ray electron diffraction patterns of the CaCO 3 @E. coli composite blocks prepared at different heating temperatures in Examples 1 and 5-9 of the present invention; Figure 4 These are the X-ray electron diffraction patterns of the pure calcium carbonate material blocks prepared at different heating temperatures in Comparative Examples 2-6 of the present invention; Figure 5 These are the scanning electron microscope images of the CaCO 3 @E. coli composite blocks prepared at different heating temperatures in Examples 1 and 5-9 of the present invention; Figure 6 These are the flexural strength diagrams of the CaCO 3 @E. coli composite blocks prepared at different heating temperatures in Examples 1 and 5-9 of the present invention and the pure calcium carbonate material blocks prepared in Comparative Example 3; Figure 7 These are the fracture toughness diagrams of the CaCO 3 @E. coli composite blocks prepared in Example 6 of the present invention and the pure calcium carbonate material blocks prepared in Comparative Example 3. Detailed implementation manners

[0012] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0013] In a first aspect, the present invention provides a method for preparing a composite powder of Escherichia coli-coated calcium carbonate, comprising the following steps: S1. Provide a buffer solution containing calcium ions, an aqueous solution containing carbonate ions, and natural Escherichia coli (E. coli / GFP) that has expressed GFP; S2. Mix and stir the natural Escherichia coli that has expressed GFP and the buffer solution containing calcium ions to obtain a suspension; S3. Dropwise add the aqueous solution containing carbonate ions to the suspension, and after the addition is completed, perform centrifugation, washing, and drying to obtain a composite powder of Escherichia coli-coated calcium carbonate (CaCO 3 @E. coli).

[0014] In this embodiment, in step S1, in the buffer solution containing calcium ions, the calcium ions are derived from at least one of calcium chloride and calcium nitrate.

[0015] In this embodiment, in step S1, in the calcium ion-containing buffer solution, the concentration of calcium ions is 0.02 to 0.1 mol / L.

[0016] In this embodiment, in step S1, the calcium ion-containing buffer solution further includes N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (hepes), and the concentration of hepes is 0.01 to 0.03 mol / L.

[0017] In this embodiment, in step S1, the pH of the calcium ion-containing buffer solution is 6.9 to 7.1, and further 7.

[0018] In this embodiment, in step S1, in the aqueous solution containing carbonate ions, the carbonate ions are derived from sodium carbonate.

[0019] In this embodiment, in step S1, in the aqueous solution containing carbonate ions, the concentration of carbonate ions is 0.02 to 0.1 mol / L.

[0020] In this embodiment, in step S1, the aqueous solution containing carbonate ions further includes sodium chloride, and the concentration of sodium chloride is 0.09 to 0.11 mol / L. The present invention maintains the pH of the system at neutral by introducing sodium chloride.

[0021] In this embodiment, the volume ratio of the calcium ion-containing buffer solution to the aqueous solution containing carbonate ions is 1:(0.9 to 1.1).

[0022] In this embodiment, the volume of the aqueous solution containing carbonate ions is 25 to 50 mL.

[0023] In this embodiment, in step S1, the number of natural Escherichia coli expressing GFP is 10 9 cells.

[0024] In this embodiment, in step S1, the culture process of natural Escherichia coli expressing GFP includes: Mix the first natural Escherichia coli expressing GFP, the first kana antibiotic, and the first sterile LB solution, and perform the first shaker reaction to obtain the first product; Add the second sterile LB solution and the second kana antibiotic to the first product, and perform the second shaker reaction to obtain the second product; Add IPTG antibiotic to the second product, perform the third shaker reaction, and then obtain the second natural Escherichia coli expressing GFP by centrifugation and washing.

[0025] In the present invention, by adding kana antibiotic during the cultivation of natural Escherichia coli expressing GFP, the growth and reproduction of other strains can be inhibited, and more Escherichia coli can be derived; by adding IPTG antibiotic, it can be made to have fluorescence characteristics.

[0026] Among them, the concentrations of the first LB sterile solution and the second LB sterile solution are both 20 - 30 g / L, and further 25 g / L.

[0027] Among them, the concentrations of the first kana antibiotic and the second kana antibiotic are both 40 - 60 μg / mL.

[0028] Among them, the volume ratio of the first LB sterile solution to the first kana antibiotic is (1000 - 1200):1.

[0029] Among them, during the first shaker reaction, the temperature is 37 °C, the time is 12 - 14 h, and the shaker rotation speed is 200 - 250 rpm.

[0030] Among them, the volume ratio of the first LB sterile solution to the second LB sterile solution and the second kana antibiotic is (50 - 60):(2800 - 3200):1.

[0031] Among them, during the second shaker reaction, the temperature is 37 °C, the time is 2 - 4 h, and the shaker rotation speed is 200 - 250 rpm.

[0032] Among them, the concentration of IPTG antibiotic is 0.4 - 0.6 mM.

[0033] Among them, the volume ratio of the first LB sterile solution to IPTG antibiotic is (15 - 20):1.

[0034] Among them, during the third shaker reaction, the temperature is 37 °C, the time is 2 - 4 h, and the shaker rotation speed is 200 - 250 rpm.

[0035] In this embodiment, in step S2, the temperature of the mixing and stirring is room temperature, the time of the mixing and stirring is 0.5 - 1.5 h, and the rotation speed of the mixing and stirring is 400 - 450 rpm.

[0036] In this embodiment, in step S3, the temperature of the dropping is room temperature, and the dropping rate is 2.5 - 3.5 mL / min.

[0037] In this embodiment, in step S3, the drying method is freeze-drying.

[0038] Among them, the temperature of the freeze-drying is -50 - -40 °C, and the time is 12 - 24 h.

[0039] Second aspect, the present invention provides a powder of Escherichia coli-coated calcium carbonate composite material, which is obtained by the preparation method of the Escherichia coli-coated calcium carbonate composite material powder provided in the first aspect of the present invention.

[0040] Third aspect, the present invention provides a preparation method of a block of Escherichia coli-coated calcium carbonate composite material, comprising the following steps: Obtaining a block of Escherichia coli-coated calcium carbonate composite material by cold sintering the powder of Escherichia coli-coated calcium carbonate composite material.

[0041] In this embodiment, the sintering temperature is 37~250°C, including but not limited to 37°C, 75°C, 150°C, 200°C, 250°C, etc., the heat preservation time is 2~3h, the heating rate is 5~10°C / min, and the applied pressure is 500~700MPa.

[0042] Fourth aspect, the present invention provides a block of Escherichia coli-coated calcium carbonate composite material, which is obtained by the preparation method of the block of Escherichia coli-coated calcium carbonate composite material provided in the third aspect of the present invention.

[0043] Example 1 (1) Weigh 0.5549 g of calcium chloride and 0.238 g of hepes and dissolve them in 50 mL of deionized water, stir evenly at 450 rpm for 10 min to fully dissolve the solid, and adjust the pH value of the system to 7 with a 2 M NaOH solution to prepare a CaCl 2 / hepes mixed aqueous solution; weigh 0.5307 g of sodium carbonate and 0.29 g of sodium chloride and dissolve them in 50 mL of deionized water, stir evenly at 450 rpm for 10 min to fully dissolve the solid, and prepare a NaCO 3 / NaCl mixed aqueous solution.

[0044] (2)At room temperature, weigh 25 g of LB broth medium (LB) using an electronic balance and dissolve it in 1 L of deionized water. Stir it evenly at 350 rpm for 15 min, then pour it into conical flasks of 300 mL, 300 mL, 300 mL, and 100 mL respectively, and then perform sterilization treatment to obtain sterile LB solution. After the sterile LB solution cools down, pour 100 mL of the sterile LB solution into 3 15-mL centrifuge tubes (with a capacity of 5 - 6 mL), and add a small amount of E. coli / GFP strain and 5 μL of kana antibiotic (concentration: 50 μg / mL) to the above 3 centrifuge tubes respectively. Let it react on a shaker for 12 h (shaker speed: 220 rpm, temperature: 37 °C); then pour the 3 centrifuge tubes into the above 3 conical flasks respectively, and add 100 μL of kana antibiotic (concentration: 50 μg / mL). Let it react on a shaker under the same conditions for about 3 h. After seeing obvious bacterial strain reproduction; then add 300 μL of IPTG antibiotic (concentration: 0.5 mM), and after reacting on the shaker for 3 h, collect the bacteria through a centrifuge device. Wash it 3 times with deionized water to obtain E. coli / GFP-IPTG strain. After calculation, there are about 10 9 individuals in each conical flask.

[0045] (3)At room temperature, pour the E. coli / GFP-IPTG strain (10 9 individuals) into 50 mL of CaCl 2 / hepes mixed aqueous solution, stir it evenly at 450 rpm for 1 h to obtain CaCl 2 / E. coli-hepes suspension; slowly drip 50 mL of NaCO 3 / NaCl mixed aqueous solution into the above CaCl 2 / E. coli-hepes suspension at a rate of 2.5 mL / min at room temperature. During the titration process, stir evenly to form white flocculent particles until the addition of the NaCO 3 / NaCl mixed aqueous solution is completed to obtain a precipitate dispersion; quickly centrifuge the precipitate dispersion, wash it 5 times with deionized water, and perform freeze-drying treatment to obtain CaCO 3 @E. coli composite powder; the temperature of freeze-drying is -50 ~ -40 °C, and the time is 16 h; (4)Simultaneously heat the CaCO 3 @E. coli composite powder at 37 °C and apply a pressure of 700 MPa for 2 h, with a heating rate of 10 °C / min, to obtain a CaCO 3 @E. coli composite block.

[0046] Example 2 Compared with Example 1, the only difference is that step (1) is adjusted as follows: (1) Weigh 0.27745 g of calcium chloride and 0.119 g of hepes and dissolve them in 25 mL of deionized water. Stir evenly at 450 rpm for 10 min to fully dissolve the solid. Then, adjust the pH value of the system to 7 using a 2 M NaOH solution to prepare a CaCl 2 / hepes mixed aqueous solution; weigh 0.26535 g of sodium carbonate and 0.145 g of sodium chloride and dissolve them in 25 mL of deionized water. Stir evenly at 450 rpm for 10 min to fully dissolve the solid to prepare a NaCO 3 / NaCl mixed aqueous solution.

[0047] Example 3 Compared with Example 1, the only difference is that step (1) is adjusted as follows: (1) Weigh 0.11098 g of calcium chloride and 0.119 g of hepes and dissolve them in 25 mL of deionized water. Stir evenly at 450 rpm for 10 min to fully dissolve the solid. Then, adjust the pH value of the system to 7 using a 2 M NaOH solution to prepare a CaCl 2 / hepes mixed aqueous solution; weigh 0.10614 g of sodium carbonate and 0.145 g of sodium chloride and dissolve them in 25 mL of deionized water. Stir evenly at 450 rpm for 10 min to fully dissolve the solid to prepare a NaCO 3 / NaCl mixed aqueous solution.

[0048] Example 4 Compared with Example 1, the only difference is that step (1) is adjusted as follows: (1) Weigh 0.05549 g of calcium chloride and 0.119 g of hepes and dissolve them in 25 mL of deionized water. Stir evenly at 450 rpm for 10 min to fully dissolve the solid. Then, adjust the pH value of the system to 7 using a 2 M NaOH solution to prepare a CaCl 2 / hepes mixed aqueous solution; weigh 0.05307 g of sodium carbonate and 0.145 g of sodium chloride and dissolve them in 25 mL of deionized water. Stir evenly at 450 rpm for 10 min to fully dissolve the solid to prepare a NaCO 3 / NaCl mixed aqueous solution.

[0049] Example 5 Compared with Example 1, the only difference is that step (4) is adjusted as follows: (4) The CaCO 3@The E. coli composite powder is treated for 2 h with simultaneous heating at 75 °C and application of a pressure of 700 MPa, with a heating rate of 10 °C / min, to obtain CaCO 3 @E. coli composite block.

[0050] Example 6 Compared with Example 1, the only difference is that step (4) is adjusted as follows: (4) The CaCO 3 @E. coli composite powder is treated for 2 h with simultaneous heating at 100 °C and application of a pressure of 700 MPa, with a heating rate of 10 °C / min, to obtain CaCO 3 @E. coli composite block.

[0051] Example 7 Compared with Example 1, the only difference is that step (4) is adjusted as follows: (4) The CaCO 3 @E. coli composite powder is treated for 2 h with simultaneous heating at 150 °C and application of a pressure of 700 MPa, with a heating rate of 10 °C / min, to obtain CaCO 3 @E. coli composite block.

[0052] Example 8 Compared with Example 1, the only difference is that step (4) is adjusted as follows: (4) The CaCO 3 @E. coli composite powder is treated for 2 h with simultaneous heating at 200 °C and application of a pressure of 700 MPa, with a heating rate of 10 °C / min, to obtain CaCO 3 @E. coli block composite.

[0053] Example 9 Compared with Example 1, the only difference is that step (4) is adjusted as follows: (4) The CaCO 3 @E. coli composite powder is treated for 2 h with simultaneous heating at 250 °C and application of a pressure of 700 MPa, with a heating rate of 10 °C / min, to obtain CaCO 3 @E. coli composite block.

[0054] Comparative Example 1 Compared with Example 1, the only difference is that in step (3), after the dropping is completed, it is uniformly stirred at 450 rpm for 12 h to obtain a precipitate dispersion.

[0055] Comparative Example 2 Compared with Example 1, the only difference is that in step (3), instead of using the E. coli / GFP-IPTG strain, a CaCl 2 / hepes mixed aqueous solution and a NaCO 3 / NaCl mixed aqueous solution were directly used to prepare pure calcium carbonate powder (heating temperature: 37°C).

[0056] Comparative Example 3 Compared with Example 6, the only difference is that in step (3), instead of using the E. coli / GFP-IPTG strain, a CaCl 2 / hepes mixed aqueous solution and a NaCO 3 / NaCl mixed aqueous solution were directly used to prepare pure calcium carbonate powder (heating temperature: 100°C).

[0057] Comparative Example 4 Compared with Example 7, the only difference is that in step (3), instead of using the E. coli / GFP-IPTG strain, a CaCl 2 / hepes mixed aqueous solution and a NaCO 3 / NaCl mixed aqueous solution were directly used to prepare pure calcium carbonate (heating temperature: 150°C).

[0058] Comparative Example 5 Compared with Example 8, the only difference is that in step (3), instead of using the E. coli / GFP-IPTG strain, a CaCl 2 / hepes mixed aqueous solution and a NaCO 3 / NaCl mixed aqueous solution were directly used to prepare pure calcium carbonate powder (heating temperature: 200°C).

[0059] Comparative Example 6 Compared with Example 9, the only difference is that in step (3), instead of using the E. coli / GFP-IPTG strain, a CaCl 2 / hepes mixed aqueous solution and a NaCO 3 / NaCl mixed aqueous solution were directly used to prepare pure calcium carbonate powder (heating temperature: 250°C).

[0060] Test Group The CaCO 3 @E. coli composite powder prepared in the above Examples 1-4 and Comparative Example 1 was subjected to XRD testing, and the test results are shown in Figure 1 and 2 .

[0061] The CaCO 3XRD tests were carried out on the E. coli composite material blocks and the pure calcium carbonate material blocks prepared in Comparative Examples 2-6. The test results are shown in Figure 3 and 4 .

[0062] SEM tests were carried out on the CaCO 3 @E. coli composite material blocks prepared in Examples 1 and 5-9 above. The test results are shown in Figure 5 .

[0063] Three-point bending strength tests were carried out on the CaCO 3 @E. coli composite material blocks prepared in Examples 1 and 5-9 above and the pure calcium carbonate material blocks prepared in Comparative Example 3. The test results are shown in Figure 6 .

[0064] Fracture toughness tests (single-edge notched beam) were carried out on the CaCO 3 @E. coli composite material blocks prepared in Example 6 above and the pure calcium carbonate material blocks prepared in Comparative Example 3. The test results are shown in Figure 7 .

[0065] Please refer to Figure 1 , it can be seen from Figure 1 that in Examples 1-4 of the present invention, the successful preparation of pure vaterite particles can be achieved. It shows that when the solution volume is 50 mL, by using the method of the present invention (directly centrifuging after titration), stable pure vaterite crystal forms can be obtained within the range of calcium ion and carbonate ion concentrations of 10-50 mM. Moreover, when the solution volume is doubled, no crystal form transformation occurs, indicating that the process of the present invention is stable and suitable for large-scale production.

[0066] Please refer to Figure 2 , it can be seen from Figure 2 that after complete titration, continuing to stir for 12 h will cause partial crystal form transformation to generate calcite, which also indicates that the process parameters of the present invention can prepare pure vaterite-type calcium carbonate with stable crystal form and shorter time consumption.

[0067] Please refer to Figures 3 - 4 , it can be seen from Figures 3 - 4 that both temperature and pressure will affect the crystal form transformation of vaterite, but the degree of crystal form transformation is greatly reduced under the action of E. coli / GFP.

[0068] Please refer to Figure 5 , it can be seen from Figure 5 that at a heating temperature of 37 °C, there are still rod-shaped holes left by Escherichia coli. However, as the heating temperature increases, the block becomes denser and the remaining holes deform and disappear.

[0069] Please refer to Figure 6 , it can be seen from Figure 6 that the bulk prepared by the method of the present invention at a heating temperature of 100 °C has the highest flexural strength, and the CaCO 3 @E. coli composite bulk has a higher flexural strength than the pure calcium carbonate material bulk, indicating that the addition of E. coli / GFP has significantly improved the mechanical properties of the composite material.

[0070] Please refer to Figure 7 , it can be seen from Figure 7 that with the incorporation of E. coli / GFP, due to the interfacial action between E. coli and CaCO 3 , crack deflection occurs, resulting in a significant improvement in its toughness.

[0071] In summary, the present invention effectively blocks through the strong interaction between E. coli / GFP and CaCO 3 , and quickly centrifuges and washes after titration, inhibiting the formation of calcite and obtaining spherical vaterite powder composed of nanoparticles; only calcium source, carbonate radical, and sodium chloride solution for maintaining a neutral solution are used in the synthesis process of the present invention, and no other organic substances such as surfactants, guiding agents, and templating agents need to be added, and no other impurities are doped in the product, with high purity; no stirring step is taken after the titration of the present invention, greatly shortening the production time, reducing the cost and improving the production efficiency; the operation method of the present invention is simple, low-cost, suitable for large-scale production, has a wide application range, and provides a new research idea for new bionic materials.

[0072] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing Escherichia coli coated calcium carbonate composite material powder, characterized in that: The following steps are involved: Providing a buffer solution containing calcium ions, an aqueous solution containing carbonate ions, and naturally occurring Escherichia coli expressing GFP; The natural Escherichia coli expressing GFP and the buffer containing calcium ions are mixed and stirred to obtain a suspension; The aqueous solution containing carbonate ions is added dropwise to the suspension, and after the addition is completed, the mixture is centrifuged, washed, and dried to obtain Escherichia coli-coated calcium carbonate composite material powder.

2. The method for preparing the Escherichia coli coated calcium carbonate composite material powder according to claim 1, characterized in that: In the calcium ion-containing buffer, the calcium ions are derived from at least one of calcium chloride and calcium nitrate; and / or, In the calcium ion-containing buffer, the concentration of calcium ions is 0.02-0.1 mol / L; and / or, The pH of the calcium ion-containing buffer is 6.9-7.

1.

3. The method for preparing the Escherichia coli coated calcium carbonate composite material powder according to claim 1, characterized in that: In the aqueous solution containing carbonate ions, the carbonate ions are derived from sodium carbonate; and / or, In the aqueous solution containing carbonate ions, the concentration of carbonate ions is 0.02-0.1 mol / L.

4. The method for preparing the Escherichia coli coated calcium carbonate composite material powder according to claim 1, characterized in that: The calcium ion-containing buffer further comprises N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid, and the concentration of the N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid is 0.01-0.03 mol / L; and / or, The aqueous solution containing carbonate ions also includes sodium chloride, and the concentration of the sodium chloride is 0.09-0.11 mol / L.

5. The method for preparing the Escherichia coli coated calcium carbonate composite material powder according to claim 1, characterized in that: The volume ratio of the buffer solution containing calcium ions to the aqueous solution containing carbonate ions is 1:(0.9-1.1); and / or, The volume of the aqueous solution containing carbonate ions is 25-50 mL; and / or, The number of the naturally occurring GFP-expressing Escherichia coli is 10 9 indivual.

6. The method for preparing the Escherichia coli coated calcium carbonate composite material powder according to claim 1, characterized in that: The culture process of the natural Escherichia coli expressing GFP includes: Mixing a first naturally occurring GFP-expressing Escherichia coli, a first kana antibiotic, and a first LB sterile solution, and performing a first shaking reaction to obtain a first product; Add a second LB sterile solution and a second kana antibiotic to the first product, perform a second shaking reaction, and obtain a second product; Add IPTG antibiotic to the second product, perform a third shaking reaction, and then centrifuge and wash to obtain a second natural GFP-expressing Escherichia coli; wherein, The concentrations of the first LB sterile solution and the second LB sterile solution are both 20-30 g / L; and / or, The concentrations of the first kana antibiotic and the second kana antibiotic are both 40-60 μg / mL; and / or, The concentration of the IPTG antibiotic is 0.4-0.6 mM; and / or, The volume ratio of the first LB sterile solution to the first kana antibiotic is (1000-1200):1; and / or, The volume ratio of the first LB sterile solution to the second LB sterile solution and the second kana antibiotic is (50-60): (2800-3200): 1; and / or, The volume ratio of the first LB sterile solution to the IPTG antibiotic is (15-20):1; and / or, During the first shaking reaction, the temperature is 37°C, the reaction time is 12-14 hours, and the shaking speed is 200-250 rpm; and / or, During the second shaking reaction, the temperature is 37°C, the reaction time is 2-4 hours, and the shaking speed is 200-250 rpm; and / or, During the third shaking reaction, the temperature is 37° C., the reaction time is 2 to 4 hours, and the shaking speed is 200 to 250 rpm.

7. The method for preparing the Escherichia coli coated calcium carbonate composite material powder according to claim 1, characterized in that: The mixing temperature is room temperature, the mixing time is 0.5 to 1.5 hours, and the mixing speed is 400 to 450 rpm; and / or, The temperature of the dropping is room temperature, and the rate of the dropping is 2.5-3.5 mL / min.

8. An Escherichia coli coated calcium carbonate composite material powder, characterized in that: The Escherichia coli coated calcium carbonate composite material powder is obtained by the preparation method of the Escherichia coli coated calcium carbonate composite material powder according to any one of claims 1 to 7.

9. A method for preparing a composite material block of Escherichia coli coated with calcium carbonate, characterized in that: The following steps are involved: The E. coli coated calcium carbonate composite material powder according to claim 8 is subjected to a cold sintering process to obtain an E. coli coated calcium carbonate composite material block; wherein, The sintering temperature is 37~250℃, the holding time is 2~3h, the heating rate is 5~10℃ / min, and the applied pressure is 500~700MPa.

10. An Escherichia coli coated calcium carbonate composite material block, characterized in that: The Escherichia coli-coated calcium carbonate composite material block is obtained by the preparation method of the Escherichia coli-coated calcium carbonate composite material block according to claim 9.

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