FIG 4.

Aggregation of exponential or stationary-phase K-12 E. coli by IgG1 or Fab. (A) Aggregation was imaged on a Cellular Technology Limited (CTL) Immunospot device to visualize bacterial pellets. Aggregation of bacteria prevents the formation of a denser pellet. (B) Aggregation of stationary-phase K-12 E. coli by brightfield microscopy. (C) Number of clumps (five or more bacteria in direct contact) per 100× objective field from brightfield microscopy (n = 8 random images per condition) were analyzed by Mann-Whitney U test. Data are representative of two independent experiments, and error bars show standard deviation.