The Torpedo

Bacteria Working in the Shadows: Bdellovibrio

Bell Biv DeVoe, R&B spin-off group from the early 1990s, hit it big with smash single, “Poison.” Chances are that while the group crooned “Girl, I must warn you,” it was unaware of the predatory microbe Bdellovibrio bacteriovorus.

This unique genus of gram-negative aerobic bacteria will invade and, in most cases, devour its prey entirely. (Gram-positive bacteria — named for the test that identified them — feature a thick cellular wall of protein and sugar compounds that helps store energy and provides structural strength.)

Found in ocean and fresh water, sewage, soil and mammal intestines, Bdellovibrio (aka the Torpedo) preys upon other plant, animal and human gram-negative bacteria. A comma-shaped bacterium with small, sheathed flagella, Bdellovibrio attacks its prey by colliding with it at speeds of more than a hundred times its length per second. The impact creates a small incision in the prey’s outer cell membrane, which The Torpedo uses to penetrate the periplasmic space of its victim.

Once inside, The Torpedo seals the wound and secretes hydrolytic enzymes that break down the molecules within its new host. Using the prey’s proteins, lipids, biopolymers, and nucleic acids as fuel, Bdellovibrio begins its own cellular reproduction. The attack lasts between one hour and three and produces three to six new torpedos.

There is an upside to such ruthless pillaging. Bdellovibrio victims are bacterial pathogens — thugs like E. coli (linked to food poisoning) and Pseudomonas aeruginosa (linked to cystic fibrosis). In fact, Bdellovibrio’s ominous plight proves invaluable in the treatment of water. Turns out Bdellovibrio bacteriovorus is a hip, new edition to our list of helpful bacteria.

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