Its a drizzly morning on New Yorks Upper East Side, and Rockefeller University microbiologist David Thaler is sipping a double espresso amid the retro-hippie pillows and dangling paper stars of Java Girl, a favorite haunt of the neighborhoods brainiac Nobel laureates, aging poets and famous entertainers. Thaler somehow manages to embody all three—a long, graying ponytail curling down the middle of his back, wire-frame glasses askew over expansive brown eyes, and a schnozz to rival an Einstein, Ginsberg or Allen. Thaler is one of the leading cheerleaders for a new field of biotechnology aimed at engineering the bacteria inside us to deliver drugs, destroy tumors, actively fight infection, and even vaccinate against their disease-causing kin.

Kids get cavities. Dentists fill them. It's a fairly old arrangement, but it may soon come to an end if cavities go the way of smallpox. Jeffrey Hillman's company, Oragenics, has patented a simple swab of bacteria that when wiped across a set of teeth will (allegedly) grant a lifetime of protection from tooth decay. By this fall, Hillman, a dental researcher at the University of Florida, will begin testing the new strain on 15 to 30 volunteers.