OVERVIEW

Why is biocontainment important?

In order to provide a sustainable, community-based solution, we plan to genetically modify Rhodosporidium toruloides, an oleaginous yeast that naturally produces beta-carotene and lipids, to be more robust and resource-efficient. By modifying the yeast to produce cellulase, it can then use common agricultural waste products as an energy source for synthesizing its oil. It can then be eaten as a vitamin A supplement. The yeast strain, while naturally safe and non-pathogenic, will also be genetically modified to include a kill switch for bio-containment, and optimized for oil production.

Previous strategies

When we began our journey towards finding an effective biocontainment strategy, we considered many different options including auxotrophy and a kill switch system, before eventually settling on our final strategy of a complementary auxotrophy co-culture system.

Auxotrophy prevents the production of a vital molecule by an organism, thereby forcing the organism to become reliant on the external supplementation of the molecule of interest for survival (ND1). A positive side to auxotrophy is the low mutation rate of reverting the auxotrophy back to prototrophy. Find reference that says this. However, such a system introduces high costs, and is ultimately unsustainable because of the need for supplementation.

An alternative biocontainment strategy is the introduction of a kill switch system. Such a system comes with its own positive aspects and limitations. Kill switch systems are genetic circuits that lead to the production of a toxin or inhibitory molecule following exposure to a certain stimulus, resulting in the death of the organism (1). For example, a kill switch system could involve the production of a nuclease in response to blue light. However, some limitations for this method is that the system relies upon the availability of the stimulus in order to be effective. In addition, when we talked to Dr. Robert Mayall, he explained how there is a higher rate of mutating out the kill switch system due to the fitness cost instilled in an organism.

Benefits to auxotrophy

In order to provide a sustainable, community-based solution, we plan to genetically modify Rhodosporidium toruloides, an oleaginous yeast that naturally produces beta-carotene and lipids, to be more robust and resource-efficient. By modifying the yeast to produce cellulase, it can then use common agricultural waste products as an energy source for synthesizing its oil. It can then be eaten as a vitamin A supplement. The yeast strain, while naturally safe and non-pathogenic, will also be genetically modified to include a kill switch for bio-containment, and optimized for oil production.

Bioreactor Engineering Controls

In order to provide a sustainable, community-based solution, we plan to genetically modify Rhodosporidium toruloides, an oleaginous yeast that naturally produces beta-carotene and lipids, to be more robust and resource-efficient. By modifying the yeast to produce cellulase, it can then use common agricultural waste products as an energy source for synthesizing its oil. It can then be eaten as a vitamin A supplement. The yeast strain, while naturally safe and non-pathogenic, will also be genetically modified to include a kill switch for bio-containment, and optimized for oil production.