by Christoph
It is boring to look at swarm-hunting Myxococcus bacteria in still images, you don't get any impression of their speedy efficacy. Therefore this is, again, not a "pictures" considered, but a time‑lapse recording as video clip.
A few remarks before you hit the "play" button. It is not the original video, I inverted the colors. This made sense to me, as the human brain (just mine?) falsely processes the images in a way that leads to the impression that the myxobacteria are steadily swarming down into a shallow trough and not climbing up onto and munching into an E. coli colony. An artifact caused by the lighting during the recording. Even the inverted colors do not convey a realistic impression of the real colors: the "black" fruiting bodies of Myxococcus xanthus that you see forming in the video from 0:15 on contain yellow/orange‑coated spores (χανθóς, Ancient Greek meaning "golden") as you can see here. And because of the low magnification (10× ?) you can of course not see individual M. xanthus cells (~7µm long, ~0.5 µm wide), only the global movement of whole bunches of cells (and no single E. coli cells either, of course). What you see in the 1:18 minutes-long clip of the hunting foray is a total of 2.344 frames recorded over a period of 7 days, seamlessly stiched together – a formidable microscopic achievement.
YouTube video. Frontispiece: screenshot from video
James Berleman, professor at Saint Mary’s College, Moraga CA, USA and autor of the original video clip writes in the accompanying text:
Myxococcus xanthus (delta proteobacterium) glides across surfaces using socially coordinated swarms. In this laboratory experiment, M. xanthus cells were near an E. coli colony on a low nutrient surface. While M. xanthus glides out in all directions, cell behavior changes after contact with E. coli. Lysing of E. coli cells can be observed through clearing, and correlates with contact by M. xanthus. Rippling behavior occurs within the E. coli colony as M. xanthus cells methodically oscillate back and forth, lysing their prey and catabolizing prey macromolecules. Cells that leave the E. coli colony either resume normal colonizing behavior, or aggregate into fruiting bodies, where sporulation allows cells to wait patiently for their next meal. Spacial scale, frame is 2 cm wide. Time scale, 7 days real time.
If you got "hooked" by the video clip and want to know more about Myxococcus right away, take a look at older – but not outdated – posts in STC: Defense fortifications (2015), Kiss and Make Up (2015), Microscopic Flash Mob (2013), and The Hybrid Two-Engine System of Myxobacteria (2009). In 2020, M. xanthus was named "Microbe of the Year" by the German Association for General and Applied Microbiology (VAAM), and they have dedicated a fine portrait to this predatory bacterium.
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