Minnesota iGEM 2014
Encapsulation
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The main goal of EncapsuLab was to create a system for the preservation and protection of the bacteria in our system, as well as physically separating them from the outside environment. To achieve this, we created a water-porous silica matrix using techniques developed by the Aksan and Wackett labs at the U of M. Furthermore, we developed a device to work as a proof of concept for the use of encapsulated bacteria in a real water-cleaning system. In addition to this, we conceptualized a scaling-up of our system for larger water-cleaning problems. Lastly, we developed a mathematical model to compare our
experimental data in order to better understand the biochemical networks behind our work.
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Title1
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Encapsulation Procedure
To make a silica matrix surrounding a cell, we needed a supply of silica nanoparticles and a reactive cross-linker capable of
covalently bonding reagents into a unified volume. Two solutions were prepared: one was a combination of TM-40 (colloidal
silica) and diluting components (ultrapure water and polyethylene glycol). The second solution was tetramethyl orthosilicate
(TMOS) cross-linker. In slightly acidic conditions, methyl groups of TMOS are hydrolyzed, producing methanol and the silica
cross-linker. Resuspended and washed cells are then added to the relatively innocuous colloidal solution. Upon combining
these two mixtures, a rapid polymerization linking colloidal silica together occured. In order to achieve proper bead
sphericity, we combined all of these components in an hydrophobic solution and let them set. After some experimentation, we
were able to produce beads with a consistent size. To purify the mixture, we phase-separated the silica beads by adding
water to solution, which forced them into the aqueous phase. These were then recovered to assess viability.
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The Biochemical Network
In this project, systems of mathematical equations are used to model the biochemical
network of methylmercury conversion in E. coli and to determine
the effects of changing methylmercury concentration on the conversion rate. A combination
of enzyme kinetics and protein expression equations was in the model.
The reactions below shows the four-step reaction network for the conversion of methylmercury to volatile mercury using the mer
operon in E. coli. This network involves the transport of methylmercury into the cell, its subsequent conversion into ionic and
volatile mercury, and the transport of volatile mercury to the extracellular space. This simplified network follows the proposed
mechanism of the mer operon and it captures the primary steps of methylmercury breakdown in E. coli.
[insert equation 1]
Furthermore, a system of ordinary differential equations was used to model the biochemical reactions taken place at each step of
the conversion process. The cofactors were not included in the equations because at sufficient concentrations, they do not
significantly alter the rates.
[insert equation 2]
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Mathematical Modeling
The equations used in conversion steps 3 and 4 are extracted from studies done by Maria on ionic mercury uptake by E. coli
cells (Maria, 2010). These equations can be used because ionic mercury is converted into elemental mercury which in turn
diffuses into the extracellular space; these two steps were described in the Maria paper. It is assumed that methylmercury
and ionic mercury have similar orders of magnitude of transport rate into the cell.
Since step 2 is not explicitly included in the Maria paper, a different approach was used to determine the equation. During
our literature search, we did not find any primary publications that specify the methylmercury conversion behavior of both
MerA and MerB. Our pBBRBB plasmid is designed in the way that the mer genes are induced in the presence of methylmercury and
ionic mercury. Through our literature search, we were able to calculate the steady state concentrations of basal and induced
states based on the presence of methlymercury and ionic mercury in the cytosolic space. Therefore, we used the below
equation to extrapolate the reaction rates of both the mer proteins. For details, please see Supplemental Materials A.
[insert equation 3]
The above equations show the reaction rates of the mer proteins under induced steady state. To represent the full MerA and
MerB expression, we include terms for the basal protein expression, the induction of the Mer proteins, and the degradation
of proteins. For details on the calculations, please refer to Supplemental Materials A. We have determined from our
calculations that Va and Vb resemble Vmax in the equations.
Sensitivity Analysis
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We performed sensitivity analysis to give us insight into which parameters will have the greatest effect on each species in
the reaction equations. We calculated the local derivatives of each species with respect to the parameters to determine how
much the parameters affected the result. The concentration of methylmercury in the cytoplasm was found to be most sensitive
to the V and K parameters of MerB. Additionally, the concentration of Hg in the extracellular space and cytosol were both
most sensitive to the V and K parameters of MerA.
We can use this sensitivity analysis as a guide to what parameters are most useful to improve. If we want the device to be
more efficient at methylmercury conversion, efforts should be directed towards improving the enzymatic activity of MerA and
MerB.
Biobrick Assembly
phsABC
Biobrick Assembly
Biosafety
Results Hg2
Results MethyllHg
Results phsABC
Policies & Practices
Our Policy and Practices approach this year has focused on establishing an effective two-way discourse between our team and the public in order to inform our design, educate the public, and illuminate ethical issues related to both our project and integration of public opinion into project implementation. We focused our discussion on safety, ethics, and sustainability in order to design a project that fits the needs of the public while maintaining technical viability. Our team did extensive educational outreach in addition to educating ourselves on public perception of our work. We used this input to inform our device design such that it could be implemented in a way that addresses the major concerns of both scientists and consumers. We also took steps to protect our intellectual property and to educate ourselves about the patent process. Finally, our team sought to investigate ethical issues brought up by our discourse with the public by discussing both our work and ethics related to the project with a variety of experts and ethicists.
Educational Outreach
Building on past successes, our team has been devoted to volunteering our services to the community in a number of educational venues. The team took our curriculum, first developed in 2013, and improved the structure and delivery of our lesson plans in the hopes of encouraging awareness and education on topics in synthetic biology. Since 2013 our educational outreach group ECORI (Educating Communities On Research Innovation) has taught our [[File:original, interactive classroom curriculum]] to over 200 students (K-12) and their teachers. This year we also created a mobile exhibit form of our curriculum along with a layman’s introduction to our project that we displayed on over half a dozen weekends to visitors of all ages at the Science Museum of Minnesota. Our curriculum has also been brought to several other STEM fairs and family fun events in the Twin Cities area including the 3M Science Day Fair for 3M employees and their families, UMN Biodiversity Fair, CSE Family Fun Fair, and the Middle School STEM Fair hosted by the Association of Multicultural Students at UMN. Finally, the team designed a Synthetic Biology Game Show that was presented on stage with 30 participants at the Minnesota State Fair to assess the general public’s knowledge of the subject and teach hundreds of passers-by in a way that was both engaging and interactive. Winners were rewarded with reusable bags, magnets, and gift cards donated by our sponsors. In the spirit of science, our curriculum has been ever evolving to constantly address salient topics and educational materials. The variable versions of our curriculum allow it to be flexible and practical in various settings.
Public Perception
Our team sought to inform the majority stakeholders in our community concerning the scope of our project. This year our team chose to have an exhibit catered towards adult residents at the Minnesota State Fair (the largest statewide annual gathering with over 1.8 million visitors each year) to learn how we can best design our technology to meet the needs and concerns of the people whose waters we hope to bioremediate. We delivered a short synopsis of our device, the synthetic biology involved, and safety precautions we have outlined for our project. We then presented visitors with a five question survey using a Likert Scale to gauge public perception of both our device, and the synthetic biology methods used. The survey was a huge success with over 320 participants. With such a diverse attendance, our survey captured a great cross-section of the Minnesota community that would be impacted by the implementation of our device. The results of our survey, illustrated below, informed how and where the public would be most comfortable with implementing our device, and illustrated the need for catered education addressing the public’s major concerns prior to applying our device in the environment. Our model for gauging public perception allowed for a wide, diverse crowd to be accessed. This model can be used upon request.
Intellectual Property
Documentary
We compiled this documentary in order to inform those unfamiliar with the problem of global mercury contamination and to discuss the bioethical questions of synthetic biology as they related to our device implementation. We have conducted interviews with specialists from environmental toxicology, biotechnology, and philosophy at the University of Minnesota. Through our collaboration with the 2014 Colombia iGEM Team, we further examined the current methylmercury contamination in Colombia and around the globe.
Safety in the Lab
Our Training
DEHS Introduction: Research Safety
DEHS Chemical Safety
DEHS Waste Management
Safety in the Lab
2. Our Local Rules and Regulations
Who is responsible for biological safety at our institution?
The project was discussed with the Department of Environmental Health and Safety at our university, and a plan was devised for mercury waste disposal based on their input. General biosafety guidelines found at https://www.dehs.umn.edu/bio.htm, http://www.dehs.umn.edu/bio_pracprin.htm and http://www.cdc.gov/biosafety/publications/bmbl5/bmbl.pdf were followed.
Safety in the Lab
3. Risks of Your Project Now
To mitigate risks to the safety and health of team members, or other people working in the lab:
Gloves are used in any protocol that utilizes Ethidium Bromide, including gel electrophoresis.
Lab coat, gloves, and full face shields are used when cutting gel fragments in proximity of ultraviolet light.
For handling mercury, a lab coat, inner and outer (long cuffed) nitrile gloves, lab goggles and face shields will be used, and used materials will be disposed of by the University of Minnesota Department of Environmental Health and Safety.
There are assigned incubators, hoods, and disposal containers for hazardous materials like mercury chloride.
Design features to minimize risk
kill switch proposal that would not allow the bacteria to survive outside of the encapsulation or even device holding the cells
Air tight?
non pathogenic lab strains
Attributions
Gold Medal Requirements
UMN iGEM has strived to produce Gold Medal level work through the duration of our project. Here we outline our work that specifically pertains to each of the gold medal requirements. Scroll to the right to see how we met each requirement!
Requirement 1
Improving function or characterization of an existing part
To compliment the UMN iGEM 2014 bioremediation project, we chose to improve the phsABC biological system first added to the registry by the Yale 2010 team (BBa_K393001). The operon, similar to the mer operon, bioremediates heavy metals such as zinc, cadmium, and copper. We sought to both improve and characterize the part for future utilization in our filtration device. To improve phsABC, we added a modified lac promoter to allow for constitutive expression rather than IPTG induction within the biological system, and thus make it more applicable in the environment. We also improved the characterization of their part by testing its application for biological precipitation of Iron and Cadmium in addition to their Copper testing to add to the functionality of the part.. [modify if we get to testing]
Requirement 2
Collaborations with other teams
The UMN collaborated with Wisconsin Lutheran to facilitate a week’s worth of synthetic biology curriculum by sending detailed lesson plans developed by our iGEM team, along with strains of microorganisms used to facilitate trainings. In addition, we participated in Columbia iGEM's low-budget lab exercise, who in turn provided UMN iGEM with an interview with a local environmental health specialist who has extensive knowledge of the mercury contamination problem within Columbia.
Requirement 3
Describing and evaluating questions beyond the bench
The primary goal of UMN iGEM 2014 has been to design a project in line with the major safety, ethics, and intellectual property concerns of both scientists and the public. We took the following steps to address each of these issues:
Safety: Our project gives detailed attention to the prevention of releasing genetically modified bacteria into the environment via encapsulation and the development of several killswitch proposals. The device also includes an activated carbon filter to both collect mercury and prevent release of the bacteria. During an outreach event at 3M we also discussed this filtration element of our device with one of their filtration experts to further inform our safety measures.
Ethics: We have been committed to establishing an open and productive dialogue between UMN iGEM and the public. Our surveying at the State Fair of public opinion on safety and implementation concerns of our device helped to inform our design. We believe there is great ethical importance to involving the community in the design of a device that could potentially be used on their waters. We also developed an interactive game show at the fair to actively engage the public in synthetic biology knowledge. Our dialogue with the public has also included our outreach program at local schools, the Science Museum of Minnesota, and various STEM fairs allowing us to develop a dynamic dialogue with both children and their parents. The program focuses on the understanding of DNA in order to demystify the basic principles behind synthetic biology. It is our hope that a more solid understanding of these principles may help to familiarize children with biotechnological tools and decrease misconceptions about the nature of DNA manipulation. We hope this may help to develop an informed future community of consumers and constituents to facilitate open dialogues between scientists and the public. Finally, we interviewed various experts in bioethics and scientific fields related to our project to help further inform ourselves and give essential background to those unfamiliar with the global issue of mercury contamination.
Intellectual Property: We sought to create an integrative and marketable project by developing a business plan along with marketing analysis for our device. We also educated ourselves about the patenting process via on campus seminars. Finally, we applied for a patent to protect the intellectual property of our team in order to help protect us during any future implementation of the developed business plan.
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