Microbes at war

Most environments are inhabited by a community of different microbes, all competing to gain the nutrients they need for growth and reproduction.

Microbes have been at war with each other, competing to access these nutrients for millions of years. Many have evolved ways to make chemicals that inhibit the growth or kill other microbes. In response to this chemical attack, microbes have evolved ways to resist the damaging effects of antimicrobials (you will learn more about antimicrobials and resistance in Week 3).

Viruses are the most numerous biological entities on Earth, estimated at 1 x 10³¹ virus particles (which is equivalent to 100,000,000,000,000,000,000,000,000,000,000), which is more than the number of stars there are estimated to exist in the universe. Many of these viruses are bacteriophages that infect bacteria and archaea in our oceans. They are so big that they can be seen using a light microscope. The scientist who discovered the first giant virus, mimivirus (Figure 1), initially thought it was a bacterium. These giant viruses can even be ‘attacked’ by other, smaller, viruses, called virophages.

Figure 1: Transmission electron microscope (TEM) image of a mimivirus © Ghigo E, Kartenbeck J, Lien P, Pelkmans L, Capo C, Mege JL, Raoult D

And as you can see in the animation, microbes have evolved a range of defence mechanisms that help to protect them against viral infections. You may want to read more about this in the further reading on the ViralZone, below.

This animation was created by Chris Lewis, Izzy Bahrin and Raj Bhogal, undergraduate students from the University of Reading’s Typography and Graphic Communication department.

Further reading

• Defence against bacteriophages: Restriction-Modification systems
• Defence against becteriorphages: Abortive infection
• Defence against viruses: CRISRP-Cas

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