Hi, 

In my case... i did it in laminar flow. and after pouring i dried them half open for 10 minutes.... 

In the swimming motility assay, 1.5 µL of optimized cultures was spotted at the center of a plate containing 25 mL of a semisolid medium: nutrient broth (NB; per liter: 5 g peptone and 3.0 g yeast extract, and 3 g Difco Bacto-Agar [Difco Laboratories]). The plates were incubated at 25 C for 24 h upside down. The assay was performed after the plates were allowed to dry for 9 h. To assess the swarming on agar, the plates were used on the day of preparation and the plates containing a semisolid medium (per liter: 5 g tryptone, 2.5 g yeast extract, and 5 g Difco Bacto-Agar) were inoculated (1.5 µL culture volume) with bacteria on the surface of the agar. After incubation at 25 C for 48 h, we measured the diameter of motility (migration of the bacteria through the agar) from the center towards the periphery of the plate.

As a control for swimming, you should use a flagellum mutant and as a control for swarming, you should use a type IV pili mutant. Because those are respectively responsible for swimming and swarming (by the way, what bacteria are you working on?).

For the plates, you can let them dry half open side up in a TC hood for 10-15 min.

Good luck with that.

Thibault

Thanks a lot guys!

I am actually evaluating the effect of some plant phenolics on motility in Aeromonas hydrophila and Serratia marcencens and comparing with the control without those phenolics. 

My students found some protocols and tested them, but only in 0.3 and 0.4 could they find motility. When they used higher concentrations of agar there was no motility, which makes me think that they were probably not seeing swarming but only swimming, since 0.3 and 0.4 are almost the same in my opinion. It would be super if we had those controls suggested by Thibault G Sana.

It worked beatifully! Thanks a lot!

Thanks for the update! And happy to know that it worked for you! Have a nice day.

Best,

Thibault

Hi, Dr. Sana, I was confused by "a control for swarming, you should use a type IV pili mutant." It is reported that swarming is also a flagella dependent motility. I was also confused by our results for swimming and swarming tests. Mutations in some genes lead to decreasing in swimming, but enhancing in swarming. Maybe you are right.

Please give me some ideas.

Best,

Yong-Qiang

Type IV pilli has nothing to do with swimming or swarming motility. The motor for swimming and swarming is the flagella. In swarming, bacteria move in groups on the surface of solid media, in swimming bacteria move individually using flagella. Type IV pilli is however the motor for twitching motility which is a different kind of motility. Practically speaking, on media with agar percentage greater than 0.3% swarming can be tested, below that agar percentage, swimming would be tested.

@ Md. Furkanur Rahaman Mizan, I performed the same experiment and measured the diameter. I am having problem regarding interpretation of the diameter of bacteria i.e., how much minimum diameter is required for bacteria to be classified as motile for swimming, swarming and twitching motility?