증균배지에서의 Listeria Interspecies의 경쟁생육 비교

Monitoring of Listeria monocytogenes, the causative agent of listeriosis, in food is inportant for public health. The Korean Food Standards Codex has adopted a ‘zero-tolerance’ policy for L. monocytogenes. The standard detection method of L. monocytogenes is based on enrichment. Thus, proper enrichment methods need to be instituted to ensure quality control of the detection procedures. In this study, the growth of L. monocytogenes and Listeria innocua as a mixed culture in Listeria enrichment broth (LEB) was monitored during artificial contamination of enrichment culture. We confirmed competitive growth or interspecies inhibitory activity of L. monocytogenes and L. innocua. Interspecies growth differences and the inhibitory activity of different inoculation and mixtures L. innocua against L. monocytogenes were examined. The concentration of L. monocytogenes must be 2.0 log CFU/mL or more than L. innocua to grow better than L. innocua. It is known that Listeria spp. and L. monocytogenes show growth difference during LEB, resulting in the risk of false-negative results. The inhibition of L. monocytogenes by L. innocua was always observed when present at lower concentrations. However, it was confirmed that L. innocua suppressed when L. monocytogenes was present at a higher concentration. Therefore if a mixture of Listeria spp. is present, detecting L. monocytogenes is difficult. Thus, a new enrichment broth to improve the detection rate of L. monocytogenes is needed.