The objective of this investigation is to evaluate how environmental changes that are related to the growth environment in the CF lung alters rhamnolipid production. Thirty-five P. aeruginosa isolates from Dartmouth College and Seattle Children’s Hospital were selected to observe the impact of temperature, presence of Staphylococcus aureus metabolites, and oxygen availability on rhamnolipid production. It was found that the rhamnolipid production significantly decreased for 30C versus 37C, but not at 40C. The addition of S. aureus spent media, in any of the tested conditions, did not influence rhamnolipid production. Finally, the change in oxygen concentration from normoxia to hypoxia significantly reduced rhamnolipid production. These results were compared to swarming assay data to understand how changes in rhamnolipid production impact surface-mediated motility.
Protein and gene circuit level synthetic bioengineering can require years to develop a single target. Phage assisted continuous evolution (PACE) is a powerful new tool for rapidly engineering new genes and proteins, but the method requires an automated cell culture system, making it inaccessible to non industrial research programs. Complex protein functions, like specific binding, require similarly dynamic PACE selection that can be alternatively induced or suppressed, with heat labile chemicals like tetracycline. Selection conditions must be controlled continuously over days, with adjustments made every few minutes. To make PACE experiments accessible to the broader community, we designed dedicated cell culture hardware and integrated optogenetically controlled plasmids. The low cost and open source platform allows a user to conduct PACE with continuous monitoring and precise control of evolution using light.