This is a short survey of the adaptive mutation processes that arise in non- or slowly- dividing bacterial cells and includes: (i) bacterial models in which adaptive mutations are studied; (ii) the mutagenic lesions from which these mutations derive; (iii) the influence of DNA repair processes on the spectrum of adaptive mutations. It is proposed that in starved cells, likely as during the MFD phenomenon, lesions in tRNA suppressor genes are preferentially repaired and no suppressor tRNAs are formed as a result of adaptive mutations. Perhaps the most provocative proposal is (iv) a hypothesis that the majority of adaptive mutations are selected in a pre-apoptotic state where the cells are either mutated, selected, and survive, or they die.
The SOS system and SOS mutagenesis are frequently studied, or exploited to obtain an increase in mutagenicity of bacteria. Here a short survey is made of the phenomenon of SOS response with special attention to latest and less discussed data, especially the induction of the SOS system in response to cell starvation or mutation of certain genes and the role of inducible DNA polymerases.