Health
E. coli 'can learn' to anticipate changes in their surroundings
London | May 09, 2008 3:12:54 PM IST
Scientists have shown that bacteria possess the ability to learn to anticipate change of conditions in the stomach. Saeed Tavazoie of Princeton University in New Jersey says that the new finding is based on a study on colonies of Escherichia coli, which showed that such bacterial colonies could evolve the ability to anticipate changes in their immediate environment. He says that this skill gives E. Coli the edge over other bacteria that merely adapt themselves to current conditions. Published in the journal Science, his study report suggests that E. coli colonies can develop the ability to associate higher temperatures (as found in a human mouth, for example) with a lack of oxygen (as found inside the human gut). Upon exposure to higher temperatures, adds the report, the bacteria alter their metabolism in anticipation of lowering oxygen levels. Tavazoie says that the new findings were unexpected. "For as long as people have been studying the behaviour of bacteria, they have assumed that responses to environmental stimuli occur in an action-reaction fashion," Nature magazine quoted him as saying. He says that the concept, scientifically know as homeostasis, has dominated the field for a century. "What we have found is that homeostasis is not the whole story," he said. Tavazoie claims that his study is the first to unearth evidence that bacteria have an ability for 'associative learning', and that its would not be correct to say that single-celled organisms learn in the same way as dogs or people. "Associative learning in dogs and humans happens over the course of the organism's lifetime, and involves modifications to the strength of connections between neurons in the brain. The learning that we have discovered in bacteria occurs over a long evolutionary time-scale and involves changes in the connections between networks of genes," Tavazoie said. During the course of study, Tavazoie and his colleagues used computer simulations to model the evolution of bacteria, and to determine whether it might be possible for them to develop anticipatory behaviour. After observing that the bacteria indeed seemed to develop anticipatory behaviour, the research team turned to live E. coli to see whether they could really show learning skills in the lab. The team trained E. coli by shifting them from 25 degree Celsius to 37 degree Celsius, and then from about 20 per cent oxygen content to zero. They monitored responses over hundreds of generations. Just in a few weeks, the bacteria had learnt anticipating the drop in oxygen by altering their metabolism after the temperature change. Tavazoie believe that the new research may hold implications for dealing with microbial infections and drug resistance. He says that anticipating the behaviour of microbes may also helpful in guiding industrial processes that rely on them, such as brewing. (ANI)
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