First of all, you should know our number of engineering strains, and then we will use this number to explain.

This year, our team hopes to create a biofilm material with stronger adhesion ability for metal corrosion protection. In order to prove the feasibility of this concept, we have carried out a series of molecular biology experiments, microbial experiments and electrochemical experiments. The following experimental results well prove the concept of our project. Welcome to visit our designs, experiments and results for more information.

In order to enhance the film-forming ability of BMCP-B1, we mutated the ompR gene of BMCP-B1 into ompR234.

    Studies have shown that ompR mutation can significantly increase the expression of csgA gene, thus enhancing the film-forming ability of Escherichia coli.
    We compared the film-forming ability of BMCP-B1 and BMCP-B3 by film-forming experiment.

    Please refer to Model
    The film-forming ability of BMCP-B3 is obviously stronger than that of BMCP-B1.

We transferred pCA24N-csgA-mfp5, pCA24N-csgA-spytag and pet28a-mfp-spycatcher into our chassis bacteria, hoping to enhance the adhesion of biofilm by connecting CsgA with Mfp5.
    We used crystal violet and Congo red experiments to detect biofilm content, so as to screen out the best protein binding mode. Here are the experimental results.

    We can conclude that pCA24N-csgA-spytag and pet28a-mfp-spycatcher protein connections are better.
    After film formation on the surface of X80 carbon steel, the adhesion of biofilm was tested on a shaking table at 80rpm. The following are the experimental results.

    It can be seen that the adhesion ability of biofilm has been enhanced and the anti-corrosion effect on metals is also more remarkable.

In this experiment, simulated seawater immersion electrodes were used in three-electrode electrolytic cells, and four groups of controls were set up
    Group I: Control group, blank electrode (Sterile)
    Group 2:E.coli-MG1655-CsgA-spytag strain was evenly coated on the test surface of the working electrode
    Group 3:E.coli-MG1655-CsgA-spytag + E.coli-BL21 crushing solution was uniformly coated on the test surface of the working electrode
    Group 4: BMCP was uniformly coated on the test surface of the working electrode
    In this experiment, the Gamry Framework program was used to test the corrosion electrochemistry, and each group of experiments lasted for 7 days
    The following are the experimental results and analysis:

    From the analysis of OCP curve: Eocp is an open circuit potential, and the larger its value, the smaller its corrosion tendency. In the experiment, the values of 2, 3 and 4 groups were higher than those of the blank control group, which proved that compared with the blank control group, the other three groups had less corrosion tendency, and after the third day, the 3 and 4 groups showed better anti-corrosion ability.

    Analyze from LPR curve: The ordinate Rp of LPR curve represents the resistance value, and the larger the Rp value, the more corrosion-resistant the group is. From the image, the fourth group shows a higher Rp value as a whole.

    From the polarization curve, it is analyzed that the tangent line extends from the corrosion potential (horizontal line) and the cathode linear area respectively (in the lower right corner, the tangent point can generally be located at about 120mV below the corrosion potential). The abscissa corresponding to the intersection point is the self-corrosion current density, and the ordinate is the self-corrosion potential. The self-corrosion current density can indirectly express the corrosion rate. The smaller the self-corrosion current density, the lower the corrosion rate, which proves that the corrosion resistance of this group is stronger.

    From the data in the above table, it can be seen that the corrosion current and corrosion voltage of the fourth group are significantly lower than those of the other three groups, which proves that its corrosion resistance is strong.·
    In addition, we also compared 2, 3 and 4 groups of one-day and seven-day EIS curves, which were divided into Nyquist plot (left) and Bode plot (right)

    Analysis from Nyquist plot: mainly observe the radius of arc. The larger the radius, the stronger the corrosion resistance.
    Analyze from Bode diagram: Bode diagram is divided into a mountain diagram and a slope diagram. To judge the corrosion resistance of materials, the slope diagram is mainly observed. The value of slope diagram is also called modulus value, and the modulus value in low frequency region is the equivalent impedance of circuit. Therefore, the larger the value of intersection point between slope diagram and ordinate, the more corrosion-resistant this group of materials is.
    Therefore, it can be explained that the fourth group of coatings did not show superior anticorrosion ability after 1 day, but after 7 days, both figures proved that this coating had better anticorrosion ability. The results not only prove that the coating is better after 7 days on the electrode, but also fully prove the anticorrosion effect of the coating.
    EIS graphs for four groups of materials for one day, three days, five days and seven days are shown below.

We use X80 carbon steel as the experimental material for observing corrosion and simulated seawater as the environment for biomineralization. Like electrochemical experiments, four groups of experiments were set up, which were cultured in simulated seawater for 7 days, and mineralization was photographed by electron microscope. The following are the experimental results.

    SEM can clearly see that there are obvious mineralized layers on the surface of the fourth group.
    In addition, we further tested the anti-corrosion ability of BMCP after biomineralization in seawater.

    It can be seen from the above experimental results that the biofilm materials (C4, D4) with mineralized layers still have significant anti-corrosion ability.