Safety

We work under Biosafety level 1 in order to protect ourselves and others from harm, First, we received training by the laboratory supervisor into laboratory safety, then for a good lab safety and personal precautions we wore lab coats and gloves also to prevent contaminating the cells, in addition we use special gloves and helmets depending on which experiment we are doing.

The work of our project is that Genetically modified micro organisms can harm the environment if they spread in the wrong place and could cause damage to humans as well. So in our project we try to solve this problem by constructing a genetic system that is based in a mechanism that enables us to control the life span of bacteria and to tie it to a specific environment to live in. Several risks/questions might be addressed: Firstly, what is the potential for gene transfer into unmodified organisms? Lastly, what are the risk of spontaneous mutations in the toxic gene to prevent death of the bacteria?

In order to address the the first question we found the following information: Gene transfer depends on the ability of one organism (referred to as hosts) take up DNA via conjugation. A recent publication by Caliando and Voigt (Nature Comm. 2015) introduced the idea of a CRISPR/Cas9-based degradation device that upon induction degrades targeted DNA. In principal, the adaption of this device and incorporation into our genetic circuit might prevent the risk posed in the first question. The second and the last question posed, concerns the mutation rate of lethal genes. In 1943, Luria and Delbrueck measured the rate of mutations in a kill switch from Knudsen and Karlstroem (1991). The authors grew cells (14 cycles of cell division), activated the toxic gene (relF) with IPTG and measured the survival of cells. The distribution of survival (shown as a poisson distribution) was shown to depend on the time of cell growth. Slowing down growth rates (reduced temperatures) and suboptimal growth medium (as used by us in the lab) might reduce the number of mutations in the toxic genes. Additionally, control of the expression of the protein might also decrease the rate for spontaneous mutations.