How Bacteria Become Drug Resistant

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Bacteria electrifying modern life

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Retell one of the texts.

Read the texts using your dictionary.

Answer the questions to Text 1.

Match a title to the paragraph.

How They Move
Where They're Found
What They Eat
What They Look Like
Classification
Early Origins
Bacteria

1. What place do Bacteria have in taxonomy?

2. Tell a few words about evolution and early life of Bacteria.

3. What shapes do they have?

4. Where do they live?

5. How do they move?

Batteries made with microbes could help generate power by cleaning up organic waste at the same time.

Sewage is loaded with energy-rich sugars that researchers have struggled for years to convert into useful power. To do so, investigators have experimented with nature's experts on breaking down waste — bacteria.

Scientists have experimented with a variety of bacteria, but there is one kind looks very promising and which is naturally found in many soils and sediments. Geobacter grows by breaking down organic materials and transferring electrons pretty much onto anything that looks like iron. When attacking environmental pollutants such as aromatic hydrocarbons, Geobacter can break down some 90 percent. All in all, systems incorporating Geobacter can recover up to nearly all the electrons within sewage.

Still, all the energy that bacteria could generate from wastewater could help power the considerable needs of wastewater treatment. For instances, in the United States, roughly 33 billion gallons of wastewater are treated daily for an annual cost of more than $25 billion, and some 1.5 percent of the electricity produced every year goes into wastewater treatment alone.

Aside from wastewater, another potentially vast source of energy that bacteria could exploit are the organic chemicals in ocean mud. Although humanity already taps into some of this fuel in the form of petroleum, most of this energy reservoir remains beyond reach because it is not nearly as easy to extract and use as oil.

Organic matter keeps on raining down onto marine sediments as organisms die, so the idea is that marine sediments could basically be a perpetual system for powering electronic devices.

In terms of advancing these microbial systems further, scientists have experimented with bacteria in terms of genetic engineering. So far they have managed to double power output.

Once in every several hundred million cell divisions a mutation makes a bacterium immune to an antibiotic drug. The mutation alters the bacterium's genetic code and thus its ability to use certain chemicals for its life activities. Mutations can be caused by the radiations from outer space that stream into the Earth's atmosphere, as well as by some atmospheric chemicals. As a result of the mutation, all bacteria that stem from the immune germ will be resistant to the drug unless any of them undergoes a mutation that makes the strain susceptible again. Hence, whenever a new antibiotic is developed, there will be a chance that bacteria will develop an immunity against it. But because mutations are fairly rare, doctors have a good chance of fighting a bacterial disease with the new drug before future strains become resistant.

Some members of a bacterial strain are resistant to certain drugs naturally. In the course of time they can eventually become selected through evolutionary forces to become the dominant drug-resistant forms of a pathogenic strain.

More importantly, some bacteria can pass on their drug resistance to bacteria of another strain by “infection.” Since the passing of resistance factors does not depend upon the lengthy process of mutation, it poses a much greater problem of drug immunity. As a consequence, doctors often must prescribe more than one antibiotic to fight certain diseases in the hope that this will slow bacterial resistance.

Дата добавления: 2014-01-04