Solved by a verified expert:write a summary of the article’s main points. Provide an answer to the question of how they deal genetically with changes to environment to not become extinct.(minimum 500 words)There is no sexual reproduction so how do bacteria cope with changes and not become extinct?Scientists show that in bacteria the rate of beneficial mutations — those that increase the capacity ofan organism to survive in a particular environment — is much higher than previously thought. In thecase of Escherichia coli, the bacteria studied, this is as much as 1,000 times higher than previouslybelieved. The study, just published in Science, also suggests that many more genes mutate duringbacteria adaptation to a new environment than previously thought. Both results – a much higher rateof advantageous mutations and a bigger number of genes mutating – have important implications forstudies in antibiotic resistance and also how bacteria develop the capacity to attack their host.Portuguese scientists show that in bacteria the rate of beneficial mutations – those that increase thecapacity of an organism to survive in a particular environment – is much higher than previouslythought.In the case of Escherichia coli, the bacteria studied, this is as much as 1,000 times higher thanpreviously believed. The study, just published in Science, also suggests that many more genesmutate during bacteria adaptation to a new environment than previously thought. Both results – amuch higher rate of advantageous mutations and a bigger number of genes mutating – haveimportant implications for studies in antibiotic resistance and also how bacteria develop the capacityto attack their host.Natural selection – the basis of evolution – is the process by which some organisms are morecapable of life and self-reproduction because they are better fitted to a particular environment. Andmutations are the raw material of evolution, in the sense that they are the source of newcharacteristics which equip the adapted organism with a bigger or smaller chance of survival.But mutations can be either beneficial or disadvantageous, and although beneficial mutations are thecrucial force behind adaptation and survival to a new environment, disadvantageous mutations aremuch better studied.There are several reasons for this, the first relies on the fact that while “bad” mutations are veryeasily seen – the organism tends to die and disappear – “good” mutations tend to have a very smalleffect in the overall adaptation of individuals and so are easily missed. The fact that beneficialmutations with big effects are rare is because when an organism is already living in a particularenvironment means that is already adapted to it, and so does not need (or can even go through)radical changes.The second reason is because in big populations where organism reproduce very quickly and manybeneficial mutations occur at the same time – and these are the only populations where the studiescan be done, since only in them evolution occurs on a visible timescale – there is competitionbetween organisms with different mutations. This means that in the end, those with the mostbeneficial mutations will be reproducing in higher numbers masking the other mutations – thisprocess is called “clonal interference” – and leads to an underestimation of the mutation rate. The difference in the study of Lidia Perfeito, Isabel Gordo and colleagues from the InstituteGulbenkian of Science in Lisbon, Portugal, is that they measured the mutation rate of Escherichiacoli in many different sized populations, including some small enough to avoid clonal interferencealthough big enough to avoid disadvantageous mutations to spread too easily and kill the population.Through the comparison of these different size populations, which ranged from to 20,000 cells to 10million, Perfeito, Gordo and colleagues reached an amazing conclusion: that Escherichia colimutation rate was a thousand times bigger than previously predicted and that thousand of mutationswere going overseen because “better” ones overtook them in the population.Although these studies were done in Escherichia coli – a very common bacterium found in theintestine of vertebrates, including man – the research by the group of Portuguese scientistspotentially applies to any bacteria and will be especially important in the study of disease-inducingbacteria.The importance of Perfeito, Gordo and colleagues’ results resides in two facts: first the fact that theyshow that beneficial mutations in bacteria are much more common than previously predictedsuggesting that bacteria can adapt both to anti-bacterial medication, but also to their host, muchquicker than previously thought and second the fact many more bacterial genes are mutating thanthose seen in the population what can have implications for the way evolution is understood.As the team leader explained to the Portuguese Agency of News Lusa, "This study is a substantialcontribution to the understanding of a central problem in the theory of evolution and has importantimplications for public health, more specifically for the understanding of antibiotic resistance and thedevelopment of new medicines against bacteria."Reference: Science – 317, 813 (2007), “Effects adaptive mutations in bacteria: high rate and small”
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