Invisible Friends by Robinson Jake;

Author:Robinson, Jake;
Language: eng
Format: epub
Publisher: Pelagic Publishing

Scanning electron microscope images showing the probiotic wall material porosity at 10× magnification (left), and the Bacillus subtilis cells dispersed within the material matrix as a biofilm at 2,500× magnification (right). Images provided by Richard Beckett.

This next story is about electricity, and eventually microbes, of course! In 1752, Benjamin Franklin conducted his famous experiment with a kite, a key and a lightning storm. He attached a wire to the top of the kite to act as a lightning rod. He secured a hemp string to the bottom of the kite, which conducted an electrical charge. The silk string he held in a dry barn deliberately prevented electrical conduction. He attached the metal key to the hemp string. During the storm, the loose threads on the hemp string started to stand erect, and when Franklin moved his finger towards the key, he felt a spark as the positive charges in his hand attracted the negative charges in the metal. He eventually used a Leyden jar to store the high-voltage electrical charge. This was one of the first recorded demonstrations of the connection between lightning and electricity. However, it was not the discovery of electricity, as many accounts document. Over 2,000 years before this event, the Ancient Greeks had discovered that rubbing fur on amber caused an electrical attraction.13 This is the first recorded discovery of static electricity. In the early twentieth century, archaeologists discovered pots with an iron rod and sheets of copper inside. Although the evidence is ropey, some believe this was an ancient battery that produced light in Roman times.14 By the seventeenth century, several electricity-related discoveries had been made, including an early electrostatic generator. Later in 1800, Alessandro Volta constructed an early battery – the voltaic pile – that produced a steady electric current, and in 1831 Michael Faraday created the electric dynamo, which enabled him to produce a constant electrical current. And with a blink of an eye in evolutionary timescales, we now have satellites, fMRI scanners, laptops, mobile phones, aeroplanes, automobiles and the internet.

Therefore, it is only relatively recently that humans have used electricity. You may then be surprised to learn that several common bacteria have been using – and even generating – electricity for millions of years. Enter Geobacter, the mud-dwelling bacteria!

Professor Derek Lovley, at the University of Massachusetts Amherst, is the head of the Geobacter Project.15 Derek and his team found that some bacteria naturally produce electricity. They discovered that Geobacter evolved the ability to ‘breathe’ solid lumps of iron in the soil. By doing this, they can generate electricity. Humans can harvest this electricity from the bacteria using devices known as microbial fuel cells. The fuel cells have two electrodes. One is an anode, the other is a cathode, and the two link together by an electrical connection.

As we know, many organisms, including humans, inhale oxygen and exhale carbon dioxide. The Geobacter bacteria have a different strategy because they evolved without lungs and in environments that lack oxygen. The Geobacter ingest the organic

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