A Novel Biocontainment Strategy Makes Bacterial Growth and Survival Dependent on Phosphite.

There is a growing demand to develop biocontainment strategies that prevent unintended proliferation of genetically modified organisms in the open environment. We found that the hypophosphite (HPO, HPt) transporter HtxBCDE from Pseudomonas stutzeri WM88 was also capable of transporting phosphite (HPO, Pt) but not phosphate (HPO, Pi), suggesting the potential for engineering a Pt/HPt-dependent bacterial strain as a biocontainment strategy. We disrupted all Pi and organic Pi transporters in an Escherichia coli strain expressing HtxABCDE and a Pt dehydrogenase, leaving Pt/HPt uptake and oxidation as the only means to obtain Pi.