Observation of type 1 fimbriae in S . Typhimurium LB5010 by electron microscopy. Panel A. S. Typhimurium LB5010 cells produced type 1 fimbrial appendages on the outer membrane (arrow) when cultured in LB static broth at 37°C for 48 hr (20,000 ×). Panel B. S. Typhimurium LB5010 cells did not produce type 1 fimbrial appendages on the outer membrane when cultured on LB agar at 37°C for 18 hr (20,000 ×). Bacterial cells were negatively stained with 2% of phosphotungstic acid.