乳酸菌과 腸內病原性 細菌의 拮抗作用에 關한 硏究

A study on the antagonistic action of Lactobacillus Casei and enteropathogenic bacteria

The present study has been designed to clarify the effect of Lactobacillus casei YIT 9018 on the survival of enteropathogenic bacteria in fermented milk and the competitive growth of L. casei, enteropathogenic bacteria and Bacillus cereus during fermentation in skim milk. The experimental results obtained are summarized as follows; 1. The enteropathogenic organisms were completely disappeared within 4 hours in fermented milk (pH 3.6) stored at 37℃ and almost died within 24 hrs. at 5℃. On the other hand, they were survived considerable time in 0.85% saline of pH 3.6 as present. It was assumed that the inhibitory factor on enteropathogenic bacteria associated not only with pH but with antibacterial substances produced by L. casei. 2. It was noted that the gram-negative were more susceptible than the gram-positive bacteria in fermented milk. 3. The enteropathogenic organisms were decreased dramatically within 24 hrs. when cultured with L. casei in skim milk. 4. There was no problem in fermentation despite the contamination of enteropathogenic bacteria, as they were completely disappeared within 48 hrs. during fermentation and there was no effect on the growth of L. casei, but it represented abnormal fermentation when contaminated with E. coli. 5. There was no difference in the survival of enteropathogenic bacteria in spite of the variation of inoculum size during lactic fermentation in skim milk. 6. The viable number of Bacillus cereus was not changed in fermented milk stored at 37℃ and 5℃. 7. The viable number of Bacillus cereus was increased in the ealier stage and decreased dramatically after 24 hrs. It was maintained 10³/ml after 48 hrs.