“…Bacteria replicate autonomously, in contrast to bacteriophages, and are sufficiently large to be analyzed by optical methods, including fluorescence microscopy, or high-throughput methods, such as fluorescence-activated cell sorting (FACS) (13,20,21,24,46,52,142). Since the first reports of bacterial display of heterologous proteins in 1986 by Freudl and coworkers (26) and Charbit and coworkers (17), an extraordinary number of different display systems has been established for yeasts (15,106,129,132,149), grampositive bacteria (40,69,84,102,117,119,123), and gramnegative bacteria (1,25,27,53,56,59,63,71,72,112,118,141). These systems have been employed for a wide range of biotechnical and biomedical applications and have prompted substantial progress in whole-cell biocatalysis, live vaccine development, biosorbent and biosensor development, epitope mapping, antigen delivery, inhibitor design, and protein/peptide library screening (for overviews, see references 5, 28, 67, and 143).…”