Unusual Types of Bacteria (Part 2)

. Gliding Bacteria

These filamentous gram-negative bacteria move by gliding, a slow motion on a solid surface. They resemble certain cyanobacteria except that they are colorless. Beggiatoa and Thiothrix are gliding bacteria that oxidize H2S to S0, which accumulates as sulfur granules inside the cells. Thiothrix filaments are characterized by their ability to form rosettes. Myxobacteria are another group of gliding microorganisms. They feed by lysing bacterial, fungal, or algal cells. Vegetative cells aggregate to make “fruiting bodies,” which lead to the formation of resting structures called myxospores. Under favorable conditions, myxospores germinate into vegetative cells.

. Bdellovibrio (B. bacteriovorus)

These small (0.2–0.3 mm), flagellated (polar flagellum) bacteria are predatory on gram-negative bacteria. After attaching to the bacterial prey, Bdellovibrio penetrates the cells and multiplies in the periplasmic space (space between the cell wall and the plasma membrane). Because they lyse their prey, they are able to form plaques on a lawn of the host bacterium. Some Bdellovibrio can grow independently on complex organic media.