Tag: E. coli

Bacteria that changed the world: Wolbachia

In our Bacterial World exhibition we offer a selection of ten bacteria that have changed the world, some in profound ways. In this series of short fact-file posts we present one of the ten each week. This week’s bacteria are…

Wolbachia
– the man-killers

Where they live
Up to 60 percent of insect species are infected with the bacterium Wolbachia, as are other species such as nematode worms.

Why they are important
Wolbachia selectively kills off males in many species of insect and alters the sex ratio of the population to its own advantage. However, some species of insect rely on it for protection against other threats.

How they are named
The bacteria take their name from Simeon Burt Wolbach, who along with Marshall Hertig co-discovered Wolbachia in 1924 in a mosquito.

How they work
Infected female insects pass the Wolbachia to their offspring – so the bacteria do everything they can to ensure females survive. Their strategies include killing male larvae, making males infertile, and rendering females able to reproduce without males.

Top image copyright: Joshua Blight (University of Oxford) & Steven Sinkins (University of Glasgow)

Bacteria that changed the world: Escherichia coli

In our Bacterial World exhibition we offer a selection of ten bacteria that have changed the world, some in profound ways. In this series of short fact-file posts we present one of the ten each week. This week’s bacteria are…

Escherichia coli
– the medicine-manufacturers

Where they live
Millions of Escherichia coli live harmlessly in your gut, keeping more dangerous bacteria at bay. A few strains cause food poisoning.

Why they are important
E. coli can act as a protein factory, accepting genes from other species and reproducing them. By combining DNA from more than one source, scientists can manipulate E. coli so that it manufactures human insulin.

How they are named
Escherichia coli’s name reflects its discoverer, Theodor Escherich, and the fact that he found it in the human colon.

How they work
Bacteria often contain plasmids, extra DNA rings that confer particular properties. Researchers can introduce genes into E. coli using plasmids, enabling the bacteria to make all kinds of biotechnology products from foods to medicines.

Top image: Coloured transmission electron micrograph (TEM) of two Escherichia coli bacteria. E. coli are Gram-negative bacilli (rod-shaped) bacteria. Long flagellae (thin thread-like structures) are used by the bacteria to move themselves. The spiky filaments on the sides of the bacteria are pili, thin strands of protein used when two bacteria conjugate (transfer DNA). E. coli is a normal inhabitant of the human intestine. However, under certain conditions its numbers may increase, causing infection. Magnification: x17,200 at 10 centimetres high. Copyright: Science Photo Library