Previously, using a chromosomal reversion assay system, we established that an 
adaptive mutagenic process occurs in nongrowing Bacillus subtilis cells under 
stress, and we demonstrated that multiple mechanisms are involved in generating 
these mutations (41, 43). In an attempt to delineate how these mutations are 
generated, we began an investigation into whether or not transcription and 
transcription-associated proteins influence adaptive mutagenesis. In B. 
subtilis, the Mfd protein (transcription repair coupling factor) facilitates 
removal of RNA polymerase stalled at transcriptional blockages and recruitment 
of repair proteins to DNA lesions on the transcribed strand. Here we demonstrate 
that the loss of Mfd has a depressive effect on stationary-phase mutagenesis. An 
association between Mfd mutagenesis and aspects of transcription is discussed.