THE BIG PICTURE— This photo, courtesy of Auburn environmental microbiologist Mark Liles, shows a probiotic bacterium, the rearmost, attacking a bacterium that causes disease in farm-raised channel catfish. This probiotic, or beneficial, bacterium is one of 25 that Auburn scientists have identified as natural enemies of disease-causing bacteria in commercial catfish ponds. The photo was taken at 10 times magnification under a digital dissecting microscope.