Mechanism for induction of adaptive mutations in Escherichia coli

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Abstract
When bacterial cells are subjected to a strong selective pressure it often induces specific mutations. Here a model is considered in which errors are introduced at random in one of the strands of the DNA molecule: a nick in one of the stands can initiate strand displacement rendering a region of the chromosome single-stranded. Upon conversion back to double-stranded DNA there is a certain probability of introducing errors creating a heteroduplex. If an error results in the production of an mRNA molecule encoding a product which provides a selective advantage, growth will be stimulated and the mutation can be immortalized by chromosomal replication. Otherwise, the error can be corrected by the DNA ''proof-reading'' enzymes.