FIG 1.

The growth of S. flexneri 2457T in IVLCs produces several putative adherence structures. Cultures of wild-type strain 2457T were grown overnight with static growth in the indicated media. Samples were negatively stained and imaged by electron microscopy. Images are representative of those from at least 3 biological replicates. (A) TEM analysis of 2457T grown in LB, LB supplemented with 2% glucose, or LB supplemented with 0.4% bile salts demonstrated that adherence factors were either not produced or minimally produced under these conditions. Magnification, ×25,000; scale bar, 500 nm. (B) 2457T grown in LB supplemented with both 2% glucose and 0.4% bile salts (IVLCs) revealed three types of putative adherence factors upon TEM analysis. Magnifications, ×50,000 (top row; scale bar, 500 nm) and ×100,000 magnification (bottom row; scale bar, 100 nm). Different structures are highlighted by numbered arrows. Arrow 1 points to thicker structures, arrow 2 points to thinner structures, and arrow 3 points to electron-dense aggregates. The asterisks denote rough, complex structures (refer to Discussion).