Figure 2

Cell wall structure of knock-down strains in the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) fields. (A) The control PLJR962 strain and EmbA/GlfT2_KD strains were observed by SEM at ×10,000 and ×100,000 magnification. The red arrow indicates the extracellular material around the bacteria. (B) TEM observation of the control PLJR962 strain and EmbA/GlfT2_KD strains at ×100,000 magnification and partial enlargement of the cell wall. The red arrows indicate the outer layer (OL), electron transparent layer (ETL), and peptidoglycan layer (PGL). (C) A unified scale is used to measure the thickness of OL, ETL, and PGL layers of each strain from (B) in all visual fields by Image J software. The cell walls of three bacteria in each visual field were taken for measurement. Data are plotted as mean ± SD, unpaired t-test: **P < 0.01, ***P < 0.001, and ****P < 0.0001. (D) The diameters of plaques were measured on 7H9 agar plate at timepoints of 4/7/9/11 days to reflect the biofilm formation. The plaques on day 11 are shown in the upper figure. A total of three parallel plates were used for significance analysis using unpaired t-test: *P < 0.05 and ***P < 0.001.