Team:Dundee/Safety

Question 1. Would any of your project ideas raise safety issues in terms of:

Researcher safety
Three organisms were used in this project: Escherichia coli (E. coli), Salmonella typhimurium LT2a (S. typhimurium) (Swords et al. 1997) and Clostridium difficile (C. difficile). The genes for the Type VI Secretion System (T6SS) and Biosensor biobricks originated in S. typhimurium which were then cloned into the E. coli chassis. C. difficile was also handled during the project due to this being the targeted organism.

Numerous strains of E. coli were used throughout this project, all of which possess no threat to human health. E. coli DH5α, JM110 (cloning) and MG1655 (protein expression) were utilised all of which “are disabled, non-pathogenic, non-toxicogenic, non-colonising, laboratory-adapted K12 strains, which are widely used for research purposes” ( Dundee iGEM 2011 ). The E. coli strain K38 [pGP1-2], encoding resistance to Kanamycin was also utilised for the radio labelling experiments which was perfectly safe to handle and required no extra safety.
These strains are all classed as being Risk Group 1 per WHO guidelines ( WHO 2004 ). S. typhimurium classed as a Risk Group 2 organism ( WHO 2004 )

The “non-toxic” strain of C. difficile, AY1 (Reynolds et al. 2011) was handled during cell growth experiments towards the final weeks of the project. All work carried out with C. difficile took place in the presence of an experienced researcher to ensure that correct safety procedures were adhered to such as the usage of a fume hood. According to EHO guidelines this organism is classed as level 2 organism ( WHO 2004 ).

The individual parts of the T6SS are believed to possess no harmful properties and thus no additional safety measures were carried out whilst handling these genes. The resulting biobricks are also considered to be safe for future handlers.

Some modifications were made to the original genes gained from Salmonella, these included site directed mutagenesis (SDM) in order to remove stop codons to fuse endolysin and mCherry to the ends of VgrG and Hcp. SDM was also used to remove unwanted restriction sites located within some of the genes. These modifications did not create a hazardous product and did not include the handling of dangerous chemicals.

35S-Methionine radiolabelling was carried out in order to characterise the combinatorial clones. Protein samples were prepared by an undergraduate member of the team but all practical work using the radioactive isotope was conducted by a highly experienced instructor who had clearance to do so. Handling of 35S-Methionine took place within a secure ‘hot room’, utilising the fume hood and Perspex shielding. Full safety protocols were followed at all times ( Amersham Biosciences. 2002 ).

The two plasmid vectors used in this project, pUNI-PROM and pSB1C3 were also safe to use and required no extra safety handling.
Endolysin from phage ΦCD27 was perfectly safe to use and handle. Endolysin proteins only affect bacterial cell walls and this endolysin specifically targets the cell wall of C. diff so was unharmful to other organisms (Mayer et al. 2008).

Before beginning any practical work for the project, all members of the team attended a Health and Safety seminar and the divisional Lab Manager delivered a safety tour of the lab, providing us with essential information in order to complete a compulsory checklist ( CLS 2009 ). General laboratory safety was highly stressed to ensure the safety of ourselves and others within the lab. Documents describing Standard Operating Procedures and risk assessments were made available to us. Formal training in various protocols including miniprep, gel extraction, PCR and cell transformation was also provided.
Instructions were given on the correct disposal of waste materials ensuring the safety of lab technicians (e.g. from sharps) and enabling effective autoclaving and destruction of live organisms.
Basic safety procedures were used at all times by members of the wet lab team. Personal protective equipment (PPE) was worn at all times and upon leaving the lab, PPE was removed and hands thoroughly washed in order to prevent any potential contamination with the outside environment. Our group were closely supervised throughout the project by instructors or advisors and any poor techniques were quickly spotted and corrected.

Like that of the previous Dundee iGEM team ( Dundee iGEM 2011 ), Qiagen kits were used in place of phenol based protocols, which have been linked with long term affects such as cardiovascular disease ( US dept. H&S, Phenol. 2008 ).
In replacement of ethidium bromide, a well-known carcinogenic mutagen, the stain GelRed was utilised for our agarose gels which has been specifically designed by Biotium with safety in mind ( Biotium 2011 ).

The category two carcinogen and mutagen, Acrylamide, ( US dept. H&S, Phenol. 2008 ) was used on a daily basis in order to produce the protein gels utilised for Western blot analysis. Special care was stressed by the advisors and this was taken into consideration when using this compound.

Public safety
If accidental release of our modified E. coli (vector biobrick psB1C3) were to happen, the organism would pose no more threat than the unmodified version. The Biobrick should be suitably expressed in any of the E. coli K12 strains mentioned above, which, as previously mentioned lacks “the ability to produce significant quantities of toxins that affect humans” ( Dundee iGEM 2011 ). The addition of the Biobrick should not improve the organism in any way that would make the strain hazardous to human health.

Like any bacterial transformation, resistance to an antibiotic is required to decrease the chance of contamination with other bacteria. The pUNI-PROM vector provides resistance to ampicillin, whilst pSB1C3 has chloramphenicol resistance. To ensure that this would not pose much threat to public safety, all GMO disposal guidelines were followed. Washing of hands and the removal of lab coats also greatly decreased the chance of its release.
The transfer of multi-drug resistance, however, is a growing concern. As it is hoped that this project could be further developed and put to practical use in the future, a concluding task of the project could be to remove this resistance in order to put the public’s mind at ease.

Through the addition of a biosensor, expression of our Biobrick would not be induced until tetrathionate can be detected in the local environment. The Biobrick, to our knowledge, does not provide any additional ability to produce products with the capacity to regulate the immune system, aid its survival in the environment or persevere in special storage conditions such as within an aerosol.

In the long term it is unknown how the production of this Biobrick would affect the population of C. diff. A kill switch is not being introduced into the Biobrick as it is hypothesised that once activated through inflammation, levels of C. diff will be decreased to the point where inflammation ceases. It seems unlikely that every individual C. diff will be wiped out but instead will be kept under the control of the returning normal gut flora levels. It may be possible that C. diff could build up resistance to the endolysin through alteration of its cell wall binding domain recognised by the endolysin (Mayer et al. 2008).
The laboratory in which this work was carried out is a controlled environment and requires secure gain of access, reducing the possibility for unauthorised persons to enter.

Environmental safety
It is well known that E. coli K12 strains are unable to sufficiently survive in the natural environment outside laboratory conditions (Na et al. 2006). They are unable to produce spores, harbour no ability to vaporize, cannot survive well in soil, seawater or air and so it would be unlikely for these organisms to proliferate in the outside environment. E. coli K12 strains are also themselves unable to colonise the gut, so if this project were to be developed further, it is unlikely that this would cause any problems ( EPA. 1997 ).
The Biobrick produces no known products that can play any significant role in the environment or environmental processes. The endolysin fused onto the VgrG protein is specific for C. difficile and should not pose any threat to plants or animals.
It may be possible that any number of the bioparts can change function through mutation, in which case the outcome would be unpredictable and any number of scenarios may occur. Due to the lack of homology with proteins produced/within that of pathogenic organisms, the chances of gaining a harmful ability appears to be slim. The most likely outcome would be that a loss of function would arise.