Overview

During the whole process of our project, collaborations occupy a significant position. These efforts enable us to better understand the meaning of our project and recognize what aspects we can improve. Due to the limitations of epidemic, most of our collaborations were held online. Even so, we have gained precious advice and experience from these scientific communications and sharing. We are grateful to have contributed to completing other iGEMers’ projects and to have promoted the communication among synthetic biology communities.

Our Creations

Meetup With BNUZH-China

Sharing project design

On June 29, we hosted the online meeting with BNUZH-China. Members of both teams were present and each team gave a short project presentation. We were all ebullient to show ourselves and learn from our collaborator.

Initially, we introduced our project in details: our project aims to engineer intestinal colonization bacteria in order to sense and degrade THC, the addictive substance in cannabis. The bacteria secrete C-phycocyanin out of the membrane while sensing THC, for which the users can be informed of consuming THC by observing the excrement. What is more, the bacteria degrade THC by secreting three kinds of enzymes. Besides, the bacteria have two kill switches - one will be activated by specific level of temperature and the other is for taking arabinose in purpose.

Then, BNUZH-China presented their project, which was aiming to construct a biodegradable skin regeneration stent system in vivo, based on bacterial cellulose. They firstly added small molecular modified substances to make preliminary transformation of the BC film. Then, they expressed epidermal growth factor, fibroblast growth factor and antimicrobial peptide to ensure the antibacterial and auxiliary healing properties of the system. After that, blue light was used to degrade BC stent. At last, they used the red light to start the suicide.

During the meet, we realized that we have some common designs in the projects，.so we determined to exchange experiences constantly to make progress together!

Exchange of suggestions

Suggestions from BNUZH-China: They suggested that we should put the genes of three enzymes into one kind of bacteria’s genome in order to easily regulate their expression. They had also provided us a possible way that we could refer to: transposition. Even we finally failed to reach the process of transferring these genes into the E.coli genome, we sincerely appreciate their advice.

Furthermore, by using different transcription initiation element, we may control the percentage of each enzyme.

Suggestions from BNU-China: Initially, BNUZH-China intended to use E.coli as the chassis organism while BNU-China suggested that the safety of E.coli as the chassis was difficult to guarantee and could be replaced with a safer chassis. As we further reviewed the literature, we suggested BNUZH-China changing the chassis to human-derived fibroblasts BJ. Engineered fibroblasts implanted in BC have the benefit of promoting wound repair in addition to exerting photo-controlled degradation and suicide.

Share experiment methods

For the killing switch this year, we took what BNUZH did last year for reference---the arabinose killing switch. Their engineering bacteria were also designed as intestinal. BNUZH put a gene that encodes a translation inhibitor (MazF) downstream of the L-arabinose activation promoter into the circuit to kill the bacteria by intaking arabinose. The L -Arabinose is harmless to human body and can be hardly taken by diet, so accidental trigger seldom happens. At the same time, as a translation inhibitor, MazF does not cause bacterial cell lysis and will not cause harm to native microorganisms. After overall consideration, we thought this method would be referential to our project this year. Moreover, thanks to BNUZH-China, we got the plasmid with MazF.

Hot Pot Meetup With Tsinghua

Before this meetup, we had communicated online for a long period because we were pleasantly surprised to find that both our projects used the PmrCAB system and we took part in the Online Charity Classroom together, sharing the ideas of spreading synthetic biology knowledge. To break away from the traditional stereotypical meet and greet, we chose to conduct our project at Haidilao Hotpot where we talked casually about our experiences in brainstorming, wet lab, HP and even the CRISPR. Tsinghua gave us some tips about how to efficiently purify the protein through Nickel-affinity chromatography column. And we also shared our team’s experience of PmrCAB system, since we also used it last year.

We pretty value the opportunity to meet and communicate offline, and we are grateful that this hot pot meetup has helped us gain a deeper understanding of our project's perspective and synthetic biology.

Our Cooperation

With BNSC-China

Thanks to BNSC-China, we got Escherichia coli Nissle1917, as our chassis.