L. plantarum disrupts posterior midgut ultrastructure. Transmission electron microscopy of CR (A to C), GF (D to F), and L. plantarum-monoassociated (G to I) fly posterior midguts 15 days after inoculation. Epithelium (E), progenitors (P), and visceral muscle (vm) are lableled. Arrowheads indicate large vacuoles. (A, D, and G) Direct magnification, ×1,200. Bars, 5 µm. (B, E, and H) Direct magnification, ×3,000. Bars, 1 µm. (C, F, and I) Direct magnification, ×3,500. Bars, 1 µm.