This is one of those ‘Hello!’ moments; the one that caught my eye when examining what fresh water amoebae did when they encountered bacteria.
ABc i – Computer In the first clip you can see rapidly swimming bacteria (Burkholderia pseudomallei) hit the surface of the amoebic cell, latch on and after a brief interval, being to twirl wildly (YouTube). That’s because their flagellum or swimming organelle has been tethered, and the bacillus has to rotate instead. We realised this was a prelude to entry into the amoeba, and used a flagellar knockout strain to show how the flagellum was essential to cellular penetration.
ABc ii – Computer In the second clip taken a bit later on, you can see how lots of bacilli have been gathered into feeding vacuoles which move around inside the amoebic cell. If you get the stage of bacterial growth and the ratio of bacteria to amebae right, you can show uptake of bacilli into amoebic vacuoles by coiling phagocytosis, formation of pauci-bacillarly vacuoles and eventual escape into the cytoplasm before amoebic rupture. We believe this process is how bacteria like B. pseudomallei and Legionella pneumophila learned their repertoire for intracellular pathogenesis. The fuller version with soundtrack.
These movie clips are in real time, demonstrating how quickly the process occurs. If you watch carefully, these microorganisms are communicating with each other. This is a language we’re only just beginning to understanding.
Melioidosis – μGnome
Inglis TJ, Rigby P, Robertson TA, Dutton NS, Henderson M, Chang BJ. Interaction between Burkholderia pseudomallei and Acanthamoeba species results in coiling phagocytosis, endamebic bacterial survival, and escape. Infect Immun. 2000 Mar;68(3):1681-6.
Inglis TJ, Robertson T, Woods DE, Dutton N, Chang BJ. Flagellum-mediated adhesion by Burkholderia pseudomallei precedes invasion of Acanthamoeba astronyxis. Infect Immun. 2003 Apr;71(4):2280-2.
Inglis TJ, Rodrigues F, Rigby P, Norton R, Currie BJ. Comparison of the susceptibilities of Burkholderia pseudomallei to meropenem and ceftazidime by conventional and intracellular methods. Antimicrob Agents Chemother. 2004 Aug;48(8):2999-3005.