Chemical synthesis of bacterial siderophores and applications in pathogen detection

Bacterial siderophores are a class of small organic compounds that are produced endogenously by bacteria to chelate essential ferric iron from their surroundings. Because the bioavailability of ferric iron is extremely low is physiological pH, the host of a parasitic infection can be a poor source of soluble Fe3+. Consequently, bacteria rely upon siderophore transport systems to efficiently scavenge the nutrient. Nearly every bacterial species ever isolated has evolved a set of unique enzymatic pathways for de novo synthesis of these compounds, thus exists an inimitable relationship between a genus or species of bacteria and the siderophores it produces. Our goal was to exploit the highly-refined interaction that takes place between a siderophore and its corresponding membrane-bound transporter by utilizing it as means to capture and identify a pathogen more rapidly and economically than standardized PCR methodology. To achieve this, we developed a robust lab-on-a-chip device that consists of a surface-mounted siderophore that is capable of capturing its cognate pathogen with a high degree of accuracy. With this device, bacterial capture occurred in a predetermined pattern, and was verified using a benchtop light microscope. This simple and relatively inexpensive method of pathogen detection may allow for widespread use of the device, while simultaneously reducing the time it takes to diagnose bacterial infections. Until recently, researchers have obtained siderophores for research using complicated, time-consuming techniques that involve isolating siderophore from large bacterial supernatants followed by extensive purification. Our goal was to avoid disadvantages associated with siderophore isolation methodology by chemically synthesizing siderophores. This would allow us to circumvent the use of potentially hazardous biologics while simultaneously improving product yield and drastically simplifying the purification process. The following work describes an improved approach for chemical synthesis of petrobactin, a Bacillus anthracis siderophore, as well as the first chemical synthesis of staphyloferrin A (SA), a siderophore of Staphylococcus aureus. We also outline the implementation of SA in an S. aureus detection device and report on its efficacy