TEM Analysis of E. coli O157 Morphology

Morphological changes of E. coli O157 strain EDL933 following incubation with hGRNL, bNK2A, or pNKL peptides were examined by TEM. Overnight cultures of O157 strain EDL933 were centrifuged (5000 rpm for 30 min) and diluted to ~2×10⁹ CFU/mL in NaPB. Fifty microliters of bacterial suspension were placed in 96-well flat-bottom polystyrene plates (Falcon #351172) and hGRNL, bNK2A, pNKL (20 μM final concentration) or NaPB were added and incubated at 37˚C for 15 (or 30 min) with continuous shaking. The bacterial suspensions were mixed with 120 μL of 3% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4) and processed for TEM as described previously [26 (link)]. Ultrathin sections were stained with uranyl acetate and lead citrate and, examined with a TEM (FEI Tecnai G2 Biotwin; FEI Co., Hillsboro, OR) and images were captured with Advanced Microscopy Technologies (AMT Inc., Danvers, MN) imaging camera. The final figures were prepared using Adobe Photoshop Elements 11 (Adobe Systems Inc., San Jose, CA).