Bacillus subtilis WN715 vs WN716 expression in early stationary phase.. Bacillus subtilis

Five batch cultures of Bacillus subtilis were subjected to laboratory evolution for 6,000 generations under conditions repressing sporulation in complex liquid medium containing glucose. Between 1,000 and 2,000 generations, variants with a distinct small-colony morphology arose and swept through four of the five populations. To understand the nature of adaptation in these variants, individual strains were isolated from one population before (WN715) and after (WN716) the sweep. In addition to colony morphology, strains WN715 and WN716 differed in their motility, aerotaxis, and cell morphology. Competition experiments of WN715 vs. WN716 showed that WN716 had gained a distinct fitness advantage during growth and the transition to stationary phase, which was more pronounced when WN715 was present in co-culture. Microarray analyses revealed candidate genes in which mutations may have produced some of the observed phenotypes. Overall design: One condition tested; 1 biological rep; 2 strains