Impact of penicillin stress on peptidoglycan peptides recycling in Bacillus spp.

In Gram-positive bacteria, the recycling of peptides resulting from peptidoglycan (PG) degradation occurring during cell growth or penicillin stress is not yet known in details. Furthermore, in B. licheniformis, cytoplasmic PG peptides accumulation have been shown to be involved in penicillin resistance1. However, the mechanism that regulates this accumulation remains unknown. To shed light upon this regulation pathway, we deleted in B. subtilis 168 and B. licheniformis MW3 ykfABCD genes postulated to be involved in PG peptide recycling1. For both strains we have quantified the cytoplasmic PG peptides during cell growth in absence or in presence of β-lactam. Penicillin stress in our case is generated by the addition of cephalosporin C. On the other hand, we studied the expression of dppABCDE-ykfABCD by following the expression of yfp reporter gene under the control of Pdpp promoter.