Purpose: The aim of the present study was to assess L. monocytogenes key virulence gene transcription during co-culture with an enterocinogenic Enterococcus faecium strain.
Methods: L. monocytogenes strain LQC 15108, serotype 4b, and E. faecium strain LQC 20005 were inoculated in BHI broth at 7 and 4 log CFU mL-1, respectively, and incubated at 5 and 37 oC. Sampling took place after 8 and 24 h of incubation, corresponding to the maximum and minimum of enterocin production, respectively. After collection of the biomass, RNA extraction, cDNA synthesis as well as real-Time qPCR were performed using commercially available kits.
Results: During growth at 5 oC, co-culture resulted in downregulation of prfA, plcA, plcB, inlA and inlC after 8 and 24 h of incubation and hly, inlB and inlJ only after 24 h of incubation. On the other hand, during growth at 37 oC, after 8 h of incubation co-culture resulted in upregulation of hly and inlC and after 24 h of incubation in downregulation of prfA and upregulation of hly, sigB and inlJ.
Significance: Exploitation of regulatory and response mechanisms of L. monocytogenes is important for the design of effective intervention strategies.