3 Exploiting the natural defences of bacteria

In Weeks 3 and 4, you saw how antibiotic resistance naturally evolved to protect bacteria as they compete for limited resources in the wild. But antibiotics are just one weapon in bacteria’s defence arsenal. Some bacteria prey on other microbes, attacking and killing them. These predatory bacteria could be exploited to kill infectious pathogens as another alternative to antibiotics.

The best known type of predatory bacteria is Bdellovibrio bacteriovorus (Figure 7).

Figure 7 The predatory bacterium Bdellovibrio bacteriovorus.

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The figure shows a scanning electron micrograph of the comma-shaped Bdellovibrio. The bacterium appears orange on a light background. It has a single long flagellum, or tail, which is about 4 times the length of the bacterium itself.

Figure 7 The predatory bacterium Bdellovibrio bacteriovorus.

Bdellovibrio bacteriovorous attaches to the surface of its prey. Once attached, it penetrates the bacterial cell membrane and replicates. Finally, the prey bacterium is lysed, releasing new B. bacteriovorous particles into the environment (Figure 8).

Figure 8 The life cycle of Bdellovibrio bacteriovorus.

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This figure comprises a schematic of the Bdellovirbrio bacteriovorus life cycle. Bdellovibrio bacteriovorus are shown as a grey comma with a long tail. Prey bacteria are shown as a cream oval. The Bdellovibrio bacteriovorus attach to and invade prey bacteria before penetrating the bacteria and elongating. Bdellovibrio bacteriovorus then lyse the prey bacteria triggering the release of Bdellovibrio bacteriovorus progeny to begin the cycle again.

Figure 8 The life cycle of Bdellovibrio bacteriovorus.