Project description:Lytic bacteriophages able to infect and kill Dickeya spp. can be readily isolated from virtually all Dickeya spp.-containing environments, yet little is known about the selective pressure those viruses exert on their hosts. Here, we identified two spontaneous phage-resistant D. solani IPO 2222 mutants, DsR34 and DsR207, resistant to infection caused by phage vB_Dsol_D5 (ΦD5) that expressed a reduced ability to macerate potato tuber tissues compared to the wild-type, phage-susceptible D. solani IPO 2222 strain. Genome sequencing revealed that mutants had point mutations in two genes encoding: secretion protein HlyD (mutant DsR34) and elongation factor Tu (EF-Tu) (mutant DsR207). Both mutations impacted the proteoms of D. solani grown in rich and minimal media. Furthermore, DsR34 and DsR207 were characterized for features essential for their ecological success in a plant environment, including the ability to use various carbon and nitrogen sources, production of plant cell wall degrading enzymes, ability to form biofilms, siderophore production, swimming and swarming motility and virulence in planta. Compared to the wild-type ΦD5-susceptible D. solani strain, mutants DsR34 and DsR207 expressed reduced ability to macerate chicory leaves and to colonize and cause symptoms in growing potato plants. The implications of the ΦD5 resistance on the ecological performance of D. solani are discussed.
Project description:Staphylococcus aureus (S. aureus) is a known pathogen able to infect humans and animals. Human S. aureus isolates are often associated with carriage of Sa3int prophages combined with loss of beta-hemolysin production due to gene disruption, whereas animal isolates are positive for beta-hemolysin associated with absence of Sa3int prophages. Sa3int prophages are known to contribute to staphylococcal fitness and virulence in human host by providing human-specific virulence factors encoded on the prophage genome. Strain-specific differences in regard to phage transfer, lysogenization and induction are attributable to yet unknown staphylococcal factors specifically influencing prophage gene expression. In this work we used tagRNA-sequencing approach to specifically search for these unknown host factors and differences in prophage gene expression. For this purpose, we established a workflow revealing the first direct comparison for differential gene expression analysis on two distinct single-lysogenic S. aureus isolates. Further, global gene expression patterns were investigated in two S. aureus isolates upon mitomycin C treatment and compared to uninduced conditions. This provides new insights into the tightly linked host-phage interaction network.
