Fig. 1: The microcolonies self-assembled from F. johnsoniae wild-type (WT).
From: Social motility of biofilm-like microcolonies in a gliding bacterium
a Schematic of a bacterial microcolony. The rod-like bacteria (gray) self-assemble into a microcolony (diameter, D and height, h), with extracellular polysaccharide (EPS) cores (red) and semi-vertical cells (or base cells, the dashed-line box) at the base (diameter, d). (Callout) The typical orientation of a single base cell relative to the substrate. b z-stack slices (8 total with 6 μm between slices) of a multiphoton microscopic image confirm the spherical, three-dimensional (3D) structure of a microcolony (D ≈ 60 μm, d ≈ 36 μm, h ≈ 45 μm). The signal indicates reduced nicotinamide adenine dinucleotide (NADH) from cell metabolism. Scale bar, 50 μm. c The under-oil open microfluidic system (UOMS) with under-oil sessile microdrops for studying the growth dynamics of F. johnsoniae. Colored water (2 μl per spot, 2 mm in diameter) was used for visualization. PDMS represents polydimethylsiloxane. Scale bar, 1 cm. (Callout) Schematic of the under-oil environment around a sessile microdrop. d Microcolonies in a microdrop with fluorescent Concanavalin A (ConA) lectin staining (12 h after initiating culture growth). Scale bar, 1 mm. e z-stack high-magnification microscopic images of microcolonies in (d the green box). Distinct EPS cores (ConA+) enveloped by attached and actively moving cells can be detected within microcolonies that do not perfectly overlap with total cell mass. Scale bar, 100 μm. The experiments in b, d, and e were performed three times for the representative result. Source data are provided as a Source Data file.
