Angely Vargas
Synthetic biology has the potential to sustainably address global environmental challenges. Genetically engineered microbes (GEMs) show promise, however, there is limited research on their environmental effects, especially in agriculture. One way to prevent the unwanted spread of GEMs in the environment is engineered auxotrophy, where a microbe has an engineered reliance upon an externally-produced nonstandard amino acid (nsAA). We are studying the environmental effects of an engineered auxotrophic pair in agricultural soil with an engineered plant that produces a non-standard amino acid (nsAA) required by an engineered microbe (GEM) to survive. To test this, we harvested live agricultural soil from the O’Donohue Family Educational Farm at Stanford University. We created five treatment groups with and without the GEM, wild-type microbe, and nsAA with four replicates each. 500 µL of treatment was inoculated per replicate in 50 mL tubes. After three days, DNA was extracted, followed by a PCR of the engineered synthetase and 16S sequencing. We found that the GEM persisted in agricultural soil regardless of the nsAA and that the biocontainment system was not effective. The 16S sequencing indicated that the GEM significantly reduced the soil’s microbial biodiversity. These findings demonstrate a need for further research on the persistence and effects of GEMs in the environment and particularly in agricultural settings. We strongly suggest that, to be ethical and responsible, further research on these environmental effects should be interdisciplinary and center the expertise of ecologists, farmers, and the communities that could be most affected by these potential environmental injustices.