In the context of globalization, many tasks are difficult to accomplish by individuals or small groups. Long-term, in-depth collaboration is more valuable than communication. In the spirit of the globally connected iGEM community, we have built a deep partnership with the SZPT-China team throughout the season. We have carried out in-depth collaboration in many fields, such as project design, experiment, mathematical modeling, education and integrated human practice.

During the project design phase, we focused on bacterial cellulose as a material during brainstorming and came up with the idea of applying bacterial cellulose to skin repair of deep wounds. Later, when investigating previous iGEM’s related projects, we found that the SZPT-CHINA team applied bacterial cellulose membranes to the treatment of burns in the 2021 competition, and achieved excellent results, and we immediately contacted SZPT-CHINA. We learned that they intend to continue developing the application of bacterial cellulose membranes in the 2022 competition, which shows that the two teams' 2022 projects will be highly relevant, so we have kept on tight contact on a long term basis.

We hold regular weekly group meetings to share the progress of the week, discuss project design, and plan for the next week.

Fig.1 BNUZH-China & SZPT-CHINA have held several group meetings throughout the whole season

At our regular meeting on July 14th, we had an in-depth discussion on the biosafety of our products. BNUZH-China pointed out that the use of live bacteria emulsion on the user's face requires careful consideration of safety issues, should standardize application condition and use procedures, and prepare emergency plans for possible problems in advance, and set up corresponding biosafety control elements in the engineering bacteria. BNUZH-China initially planned to use engineered E. coli as the chassis, anaerobically initiating cellulase-expressing bacterial cellulose membranes. SZPT-CHINA pointed out that wound healing is accompanied by angiogenesis but not a process of gradual oxygen reduction, and suggested that we can try to switch to a light control system. From this, we further reviewed the literatures and changed the anaerobic start to a light-controlled start (For more details: Engineering), and the cellulase degradation was initiated under the control of blue light .

At the beginning of the experiment, the SZPT-CHINA team shared the situation of the bacterial cellulose membrane produced by the bacterial emulsion, and found that the production film was too thin, which may cause the membrane to be unfavorable for practical use. BNUZH-China proposed to adjust the emulsion composition and increase the time of film production in an appropriate amount. The follow-up SZPT-CHINA team increased the film production time from the original half an hour to one hour, and the film thickness problem was solved.

Fig.2 Comparison of film production pictures before (a) and after (b) the SZPT-CHINA team adjusted the scheme

SZPT-CHINA said that they encountered the problem of inefficient ligation of the target fragment to the skeleton plasmid during the construction of the vector, and sought help from BNUZH-China. The BNUZH-China team introduced Gateway, Gibson and other ligation methods to them, and recommended that they try Gibson assembly , and the SZPT-CHINA team successfully built the target plasmid bphs-PcdrA-FleN-FleQ-pSEVA331 after using Gibson assembly 's method. At the same time, in terms of antioxidant experiments, the SZPT-CHINA team used the cross-section of slitting apples to carry out antioxidant experiments, and the effect was not obvious. The BNUZH-China team pointed out that it is possible to peel off the skin of the apple and then perform an antioxidant experiment on the apple sphere. Based on the suggestion, the presentation effect of the antioxidant experiment was significantly improved.

Fig.3 Experimental results of SZPT-CHINA before (a) and after (b) using the Gibson assembly method

When the BNUZH-China team amplified CenA and Cex fragments at PCR, the PCR experiment repeatedly failed due to the high GC value of the gene itself and the inappropriate primers. The SZPT-CHINA team proposed that gradient PCR could be used. The BNUZH-China team later added PCR stimulant to the reaction system and increased the denaturation temperature in the PCR program, using gradient PCR to explore the most appropriate annealing temperature, tried to use touchdown PCR to improve product specificity and finally successfully amplified and sequenced correctly.

Fig.4 Results of BNUZH-China using the target gene amplified before (a) and after (b) using the touchdown PCR

In the early stages of cell biology experiments, the BNUZH-China team often experienced poor cell growth and poor adhesion. Contamination was initially considered, but no contamination was found after new medium change and mycoplasma testing. SZPT-CHINA has proposed that cell growth may be affected due to poor serum quality in fetal bovines. Therefore, BNUZH-China replaced different brands of fetal bovine serum, and the cell growth status improved significantly.

Fig.5 The cell states before (a) and after (b) BNUZH-China replaced the medium listening to the opinion of SZPT-CHINA

On September 10th, due to the tight progress of BNUZH-China late experiments, we had not yet purchased the cellulase needed for the experiment, and learned that SZPT-CHINA still had cellulase. So on September 12th, SZPT-CHIAN sent us cellulase to help us carry out degradation control experiments. At the same time, due to the difference on membrane-producing strains and culture conditions of the two teams, the properties of the cellulose membranes are not exactly the same, and SZPT-CHINA also sent us the sterilized cellulose membranes they produced for our follow-up experiments.

Fig.6 SZPT-CHINA sent a courier order for cellulase to BNUZH-China (a) and cellulase received by BNUZH-China (b)

In our regular meeting on September 11th, we discussed some confused problems in safety form , such as some dangerous chemicals used may be ignored. This exchange reminded us to note every detail of the project to ensure safety.

At the regular meeting on August 28th, the BNUZH-China team shared a lot of experience with mathematical modeling because the SZPT-CHINA team had less experience in mathematical modeling, including modeling does not require all of their own experimental data, but requires the model to fit the experiment. SZPT-CHINA said the exchange resolved their modeling doubts.

When the two teams discussed the content related to wiki design, BNUZH-China shared wiki building experience with SZPT-CHINA, such as: Building wiki should be as concise and easy to read as possible rather than pursue complexity,; To do the adaptation of tablets, etc. SZPT-CHINA said it was greatly inspired.

Fig.7 BNUZH-China shared experience in modeling and wiki construction with SZPT-CHINA

On August 6th, BNUZH-China cooperated with the SZPT-CHINA team to hold a popular science lecture on the theme of "Entering the World of Synthetic Biology" for all undergraduate students, and invited HBUT-China, NEFU_China, NWU-China to participate together. The lecture focused on the theme of synthetic biology, and each team taught synthetic biology knowledge from multiple aspects such as biological engineering, synthetic biology safety, and synthetic biology in burns, and briefly introduced their project directions respectively. The content of BNUZH-China science is the application of synthetic biology in the protection of cultural relics and burn treatment. After the science popularization activity, the five teams held a meeting to discuss the project content of each team in depth and plan the post-event arrangement.

Fig.8 BNUZH-China gave a popular science lecture on "Entering the World of Synthetic Biology"

Fig.9 MeetUp after the lecture

The three teams of BNUZH-China, SZPT-CHINA and NEFU_China also jointly carried out the microbial hymnography collection and push activity, combining microbial knowledge with poetry to create a novel way of science popularization (For more details: Education).

Fig.10 Microbiology praise poetry activity --- An event we held together