In the process of participating in the 2022 iGEM competition, our team GXU-China
did not use any infectious or pathogenic organisms
.
The whole process was completed in the laboratory
without any open environmental experiments, animal experiments, human experiments, etc
. All our experiments and human practices
comply with the official requirements of iGEM
, and all human practices are carried out with the consent of the parties concerned,
without any infringement
.
GXU-China's entire project in 2022 is "Light regulated sewage treatment bacterial preparation with
Bacillus subtilis
as the chassis", in which the experimental part aims to convert NH
4+
, NH2
OH, NO2-
and NO3- into N2 and remove it from the water body through the "Aerobic denitrification and denitrification metabolic pathway".
The research shows that
Bacillus subtilis
itself has no harmful effect on the environment and organisms
. It is suitable for synthetic biological transformation, so
we take it as our target strain
.
1.
Considering that the intermediate product NO may be oxidized to NO2, which is harmful to organisms,
we designed the denitrification pathway
as a safety consideration, which can reduce NO to nitrogen through two enzymes, NOR and NOS, so as to
achieve harmless treatment
. Of course, we have designed and installed a nitrogen oxide gas sensor in our hardware part, which can monitor the concentration of NO and NO2 in the reactor in real time.
If the content exceeds the standard, we will change the reaction conditions or start the suicide mechanism in time to ensure that harmful gases will not be generated further
. At the same time, in the process of laboratory verification, we can also
fully ensure that NO will not leak
through external potassium permanganate solution oxidation method and balloon collection method.
2.
Our team also
designed a suicide mechanism
to induce the expression of NucA by green light irradiation, making the strain commit suicide. For safety reasons, it can
prevent engineering bacteria from leaking into the environment
and
causing damage to the ecosystem
. Secondly,
the population density can be adjusted in time
, so that the bacterial preparation can always be kept at a suitable density and maintain a suitable growth rate. Keep the most efficient treatment efficiency and prevent excessive accumulation of harmful gases.
3.
In addition,
our hardware is designed in a closed manner throughout the whole process
and does not use flowing water as the experimental object. There are
no experimental samples directly discharged into the environment
, which is more convenient for harmless treatment. We have also
designed a special feeding port
for the release of bacterial preparations to ensure that the variables of engineering strains are unique.
After the experiment, rapid sterilization can be carried out by high temperature
and ultraviolet irradiation to ensure that the strains will not spread.
At 7:00 pm on September 2, 2022,
the freshwater remediation alliance held a meeting on biosafety issues
, and the participating team included CFCA_China, Nanjing_NFLS, XJTLU-CHINA, Nanjing-China, CHINA-FAFU, GXU-China and NPU-CHINA.
The main purpose of this meeting is to
discuss our safety from three aspects
. Firstly, we aim to
prove that our experimental steps meet the safety standards
. Secondly, we aim to
prove that our engineering bacteria will not cause leakage
. Finally, we
try to ensure that our projects will not cause harm to the environment and human beings
.
After the seven teams introduced their own treatment plans, we discussed some of the current questions, and everyone put forward many points worthy of reference, and
the participants benefited a lot
. The GXU-China team gained safeyear ideas from other teams working in wastewater treatment and other areas, and discussed with other teams at a deeper level that
synthetic biology operations should be carried out within a legal and ethical framework
, after which we further improved our safety solutions based on this meeting.
