Safety is an important part of synthetic biology research and application. In addition to following laboratory safety precautions and performing correct experimental operations, the safety of engineered bacteria is also worth investigating especially for the feed industry. At the same time, the safety of the chemicals used in the project needs our evaluation. We adhere to strict laboratory safety practices throughout the project and actively solicit input from safety experts to shape our project.
Team Tongji_China obeys the safety policy of iGEM 2022. All the experiments were done in the Open Laboratory of
Innovation Practice for College Students. All the equipment and devices belonged to bio-safety level
1, and reagent cabinet was equipped for storing hazardous reagents.
Before the experiments began, all the members were required to attend to the safety training of the school.
Advisors and instructor also imparted proper experimental operations of equipment (such as PCR amplifier, clean
bench and autoclave) and reagents (such as NaOH and nucleic acid dye). All the equipment in the lab would be
regularly checked. All the experiments must be done when there are more than two people. During the stage of
project design, the usage of pathogenic bacteria would be avoided. Bacterium-polluted wastes were stored
separate from other experimental wastes and would be sterilized before abandoning, to avoid GMO leak to the
environment.
B. subtilis strains are highly safe and recognized as GRAS (Generally recognized as safe) by FDA(US Food and
Drug Administration). Also, B. subtilis is commonly used as engineering bacteria and is in the white list. It
is widely found in the intestinal tract of animals in nature and is considered as intestinal probiotics. It
has a certain history of preparing fermented food and does not produce heat-sensitizing proteins and various
toxins, so its safety level can reach food grade.
A lot of food and feed additive is produced by genetically modified (GM) microbial fermentation. In the law of
ESFA (European Food Safety Authority), GM strains are not allowed to exist in food or feed additives on the EU
market of fermentation products. In the enzyme preparation standards of International Codex Alimentarius, E.
coli has corresponding chassis residue limits, but we can’t find any information about the residue standard
against B. subtilis. B. subtilis can be used as a feed additive, but transgenic B. subtilis
cannot be added to enzyme preparations. By querying the Hygiene Standards for Feeds in China, we obtained the data on the limit
range of residue in the chassis of biological enzyme preparations.For raw materials of protein feed, the
residue of bacterial chassis should be less than 2×106 CFU/g.
The project has killed bacteria in the process of separation and purification. Because we mainly did the experiment of E. coli, so we measured the OD600 value of E. coli in our purified protein product (OD600=0.005), which met the national standards.
The hazardous chemicals used in our project include methanol, hydrochloric acid, glacial acetic acid, ammonium persulfate, β-mercaptoethanol and TEMED (tetramethyl ethylenediamine). By referring to the MSDS (Material Safety Data Sheet), we standardized its use method and did a good job in experimental protection. Also, the concentration of the chemicals won't be too high to do harm to people's health.
