Contribution | LZU-HS-China-E

Introduction

Since the beginning of the project, our team has been committed to contributing to the future iGEM team. We have made some breakthroughs in cell surface display technology, exploring global regulatory genes and hardware settings, accumulated some experience, and provided some information and help to the future iGEM team.

1、About environmental restoration

After the team's discussion, we decided to use engineering bacteria to remediate divalent cadmium pollution in wastewater, which is the most effective and repairive method we think of. Sewage remediation is a big project, which is closely related to our living environment. There is a lot of useful information on our wiki page, which can help the future iGEM team know more about sewage remediation. We hope that the future iGEM team will explore more about the field of wastewater pollution.

2、About global regulatory genes

In the experiments, we compared the function of different promoter, and recorded the bacteria on different purpose genes inserted after the growth curve in the salt water and heavy metal adsorption ability contrast, our study is high in salt heavy metal wastewater in the direction of the repair, so to have a good effect in the general water quality of high salt waste water does not work. After experimental and control data, we finally selected four genes, Inp EC20 GroESL IRre, to achieve sufficient salt tolerance and cadmium adsorption effect, and maintain due fecundity and tolerance under high salt environment. Future iGEM teams that need salt resistance can look at these genes.

3、About cell surface display technology

In order to improve the adsorption capacity and salt tolerance of the engineered bacteria and other useful functions for sewage treatment, we adopted the cell surface display technology in the engineered bacteria. Among the four genes we used, EC20 was a qualified gene that could provide the engineered bacteria with the ability to adsorb heavy metals, but EC20 could only be expressed inside the cell. INP gene can be anchored on cells to increase cell affinity and adsorption, so we combined INP with EC20 to solve the problem of external expression. This method is called cell surface display technology, and future iGEM teams can also refer to this technology for experimental purposes.

The following figure shows the arrangement of the four genes and the gene map

4、About machines that adsorb cadmium

To make this process more convenient, members of our team built an instrument for heavy metal adsorption using the activated sludge process. Engineering bacteria are added to activated sludge, which can adsorb heavy metals and be salt tolerant. Then we added stirrer, ultraviolet lamp and other accessories to make it better mixed, to ensure heavy metal precipitation and no secondary pollution. The machine we made is very simple and the cost is not too high, and it is not too difficult to use. Therefore, we also hope that this hardware can help the future iGEM team, make their experiments more convenient and stimulate their inspiration.

The following figure shows the machine model

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