Study of SP?? instability in a sigY null mutant of Bacillus subtilis

In this study, I investigate whether sigY plays a role in maintaining the SP??\ud prophage genome within the B. subtilis chromosome and if cell death in a\ud subpopulation of cells is due to SP?? induction or to loss of resistance to the\ud antibiotic sublancin. Polymerase chain reaction using the yonR and BETA\ud primers demonstrated complete loss of the SP?? genome in a sigY null mutant\ud strain because no PCR product was obtained when the yonR primers were used,\ud whereas a product was obtain using the BETA primer that are complementary to\ud the SP?? attachment site ( attBSP??). A plaque assay demonstrated that phage\ud particles are not produced when SP?? excises from the sigY null mutant, which\ud suggest the lytic cycle is not being triggered. In addition, absence of the SP??\ud genome from its normal site insertion site was detected in a subpopulation of the\ud wild type cells. This suggests that SP?? excision in a subpopulation of cells is a\ud normal process and that SP?? loss is due to excision of the genome, but not\ud induction of the lytic cycle. In conclusion, this thesis research demonstrated that\ud SP?? is lost in a subpopulation of cells in B. subtilis, and that this process is at\ud least partially regulated by SigY