Assessing Bacterial Swarming Using a Gradient Inhibitor Plate

Abstract

Source: Guo, S., et al. Quantifying Bacterial Surface Swarming Motility on Inducer Gradient Plates. J. Vis. Exp. (2022).

This video demonstrates the use of a double-layer gradient swarm plate to study bacterial swarming behavior under varying inhibitor concentrations. A plate with a gradient-forming inhibitor in the bottom layer is inoculated with bacteria and incubated. Images are captured at regular intervals to analyze the effect of inhibitor concentration on bacterial swarming.

Protocol

1. Preparation of gradient swarm plates

1. Preparation of swarm medium
   NOTE: 0.7% (w/v) agar concentration of swarm medium was used in this protocol.
   1. Prepare Lysogeny broth (LB) powder with agar in two conical flasks; each flask contains 2 g of tryptone, 2 g of sodium chloride (NaCl), 1 g of yeast extract, and 1.4 g of agar. Add double-distilled water (ddH₂O) and stir the suspension using a magnetic stir bar. Adjust the final volume to 200 mL by adding additional ddH₂O.
   2. Autoclave the solution at 121 °C for 20 min. Use an air-permeable cap or bottle sealing film with an....

Results

Figure 1: Schematic of inducer gradient swarm plate preparation, inoculation, and incubation.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Agar	Sigma-Aldrich	V900500	500 g
Ampicillin	Solarbio	A8180	25 g, ≥ 85% (GC)
Centrifuge tube	Corning	430790	15 mL
Cryogenic vial	Corning	430488	2 mL
Dimethyl sulfoxide (DMSO)	Aladdin	D103272	AR, > 99% (GC)
L(+)-Arabinose	Aladdin	A106195	98% (GC), 500 g
Petri dishes	Bkman	B-SLPYM90-15	Plastic Petri dishes,circular,90 mm x 15 mm
Resveratrol	Aladdin	R107315	99% (GC), 25 g
Sodium chloride	Macklin	S805275	AR, 99.5% (GC), 500 g
Square Petri dishes	Bkman	B-SLPYM130F	Plastic Petri dishes, square, 13 mm x 13 mm
Tryptone	Thermo Scientific Oxoid	LP0042	500 g
Yeast extract	Thermo Scientific Oxoid	LP0021	500 g
Equipments
Biochemical incubator	Blue pard	LRH-70
Tanon 5200multi imaging system	Tanon	5200CE
Thermostatic water bath	Jinghong	DK-S28