Much research has been done on the ebg operon of the bacterium Escherichia coli over the last 30 years. Although the function of the ebg operon is still unknown, it has been observed that specific mutations within this operon enable the bacterium to metabolize lactose sufficiently to allow growth. Interestingly, this growth occurs in a lacZ- genotype (gene for β-galactosidase in the lac operon). Thus, this gene has been referred to as an “evolved β-galactosidase,” and has been widely accepted as an example of “evolution in action.” Under these cultivation conditions, the ebg operon appears to harbor adaptive mutations. Mutations (at codons 92 and 977) in the ebgA gene (which codes for ebg β-galactosidase) occur consistently when an E. coli lacZ- population undergoes carbon starvation in the presence of lactose. These are the only mutations observed in the ebgA gene and these particular mutations are not found when the bacteria are subjected to different adverse environmental conditions. Mutations are also found in other genes suggesting a mechanism which has affects on the entire genome. Several models have been proposed to explain this phenomenon.

Hall’s work needs critical evaluation. Mutations in the Ebg system are clearly not an example of evolution but mutation and natural selection allowing for adaptation to the environment. Several possibilities for the function of the Ebg system are suggested. In addition, there is an assessment of the likelihood of these mutations in the ebg operon occurring in a natural setting. An implication of this research is an understanding that adaptive mutation makes “limited” changes which severely restrict its use as a mechanism for evolution.

Adaptive mutations can readily fit within a creation model where adaptive mechanisms are a designed feature of bacteria. Further understanding of these mutations in the ebg operon may help the development of a creation model for adaptation of bacterial populations in response to the adverse environmental conditions in a post-Fall, post-Flood world.


Mutation, Adaptive, ebg, Hall, lac, Hypermutable, Evolution, Natural selection


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