How small can the difference among competitors be for coexistence to occur |
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Authors: | Akiko Kashiwagi Tadashi Kanaya Tetsuya Yomo Itaru Urabe |
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Institution: | (1) Department of Biotechnology, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, 565-0871 Suita, Osaka, Japan |
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Abstract: | Closely related competitors comprising ofEscherichia coli strains having the same metabolic system and differing only with a few bases on the glutamine synthetase gene in the plasmid
pKGN were previously shown to coexist in a chemostat. The differences among these closely related competitors can be considered
large enough to allow coexistence as the level of enzyme activity is different. To bring the difference among competitors
to the slightest possible, the mutation was introduced on the noncoding region of the plasmid pKGN harbored in the wild-type
strain (strain W). The new strain, strain W’, carries the plasmid pKGN’ with a 4-base insertion at theHind III site in the polycloning site of pKGN. As the noncoding region is a nucleotide segment that is not translated into amino
acids, the relatedness between strains W and W’ is the closest possible from the genetic point of view. Interestingly, though
both strains are almost identical, they can coexist stably in a chemostat irrespective of the initial population size. These
experimental results suggest that in the natural ecosystem, no matter how akin competitors are, coexistence is not impossible. |
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Keywords: | bacterial mutants chemostat coexistence competition Escherichia coli glutaminesynthetase |
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