탈지유의 보존 및 증균증 Listeria monocytogenes와 타속균의 경합

Competition of Listeria monocytogenes with Other Organisms during Enrichment and Storage of Skim Milk

The studies were conducted to explore the effects of competitive growth inhibition between Listeria monocytogenes and other microorganisms in skim milk and enrichment broth stored at 7℃ and 30℃. The initial counts of L. monocytogenes were 3.6 log CFU/ml and were increased to 7.6 log CFU/ml after 7 days of storage at 7℃ and were increased to maximum numbers, 10.0 log CFU/ml after 1 day of storage at 30℃. The growth of L. monocytogenes in skim milk for 48 hrs with 5 other organisms (Acinetobacter spp., Streptococcus faecalis, Staphylococcus aureus., Pseudomonas putida, and Streptococcus lactis) was markedly inhibited at 30℃, but was similar with that of the control groups at 7℃. In skim milk, the growth of L. monocytogenes was slightly inhibited by the presence of Streptococcus faecalis and Streptococcus lactis at 7℃ for 48 hrs, whereas, was markedly inhibited at 30℃ for 48 hrs. However, the presence of Acinetobacter spp., Staphylococcus aureus and Pseudomonas putida, did not effect the growth of L. monocytogenes at either temperature. In incubated skim milk with 100 CFU/ml of L. monocytogenes and 10³ CFU/ml of 5 other organisms, L. monocytogenes were increased to 5. 9 log CFU/ml after 7 days of storage at 7℃. However, the growth of L. monocytogenes was decreased after 3 days and was not detected after 4 days at 30℃.