We are surrounded and inhabited by trillions of bacteria. The surface of bacteria contains unique sugars that are not found in humans, and these sugars make-up distinct patterns that act as barcodes to distinguish different strains of bacteria. It is a long-standing challenge to develop reagents to specifically identify and modify these bacterial barcodes. In this proposal, we seek to create artificial bacterial cell surfaces using genetic engineering and bacterial sugar mimics to probe interactions between bacteria and their environments. In addition to applications in antibiotic development, this work will facilitate the design of better bacterial diagnostic tools.