• Food Science of Animal Resources
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• v.28 no.5
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• pp.587-595
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• 2008

In order to develop a new starter for fermented milk, 1037 bacterial strains were isolated from raw milk. The strain that showed excellent acid producing and angiotensin converting enzyme (ACE) inhibitory activity (88.6%) was selected and identified as a Lactobacillus zeae based on the result of API carbohydrate fermentation pattern and 16S rDNA sequence. Lactobacillus zeae RMK354 was investigated further to study its physiological characteristics. It showed strong ACE inhibitory activity compared with commercial LAB starters tested. The optimum growth temperature of L. zeae RMK354 was $40^{\circ}C$ and it took 10 hr to reach pH 4.3 under this condition. L. zeae RMK354 showed more sensitive to penicillin-G, bacitracin, novobiocin, in a comparison of 14 different antibiotics, and showed most resistance to polymyxin B and vancomycin. It showed higher esterase and leucine arylamidase activities compared with 16 other enzymes. It was comparatively tolerant to bile juice and able to survive at pH 2 for 3 hr. It showed inhibitory activity against Salmonella Typhimurium with the rate of 60%. Based on these and previous results, L. zeae RMK354 could be an excellent starter culture for fermented milk with high level of ACE inhibitory activity.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.133-136
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• 2013

The purpose of this study was to compare a conventional culture method and real-time PCR for the detection of Yersinia enterocolitica (Y. enterocolitica) in sausage and in vegetable salad. Food samples inoculated with Y. enterocolitica were enriched in peptone-sorbitol bile-broth, and swabs were then streaked onto cefsulodin-irgasan-novobiocin agar. Biochemical tests for suspected colonies were performed with an API 20E strip. In parallel, real-time PCR was performed, targeting the 16S rRNA gene using 1 mL of enrichment broth. In sausage, the number of positive samples detected by culture method (49 out of 60) was similar (p>0.05) with that of real-time PCR (50 out of 60). However, the number of positive samples of real-time PCR (26 out of 60) was significantly higher (p<0.05) than that of the conventional culture method (6 out of 60) in vegetable salad. Real-time PCR could be an effective screening tool for detecting Y. enterocolitica, particularly in food samples with high levels of background flora, such as a vegetable salad.

• Food Science of Animal Resources
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• v.27 no.4
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• pp.501-508
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• 2007

In order to develop a new starter for fermented milk, Lactobacillus plantarum M23 was isolated from raw milk and investigated for physiological characteristics. It showed good tyrosinase inhibitory activity compared with commercial lactic acid bacteria. The optimum growth temperature of Lactobacillus plantarum M23 was $40^{\circ}C$ and cultures took 17 hr to reach pH 4.3. Lactobacillus plantarum M23 showed more sensitivity to Penicillin-G, Oxacillin, Novobiocin, Chloramphenicol in a comparison of 12 different antibiotics, and showed most resistance to Vancomycin. It showed higher leucine arylamidase and ${\beta}-galactosidase$ activities compared to 16 other enzymes. It was comparatively tolerant to bile juice and able to survive at pH 2 for 3 hours. It showed high resistance to Escherichia coli, Salmonella typhimurium and Staphylococcus aureus with rates of 77.8%, 86.5% and 83.8%, respectively. Based on these and previous results, Lactobacillus plantarum M23 could be an excellent starter culture for fermented milk with high resistance to melanin.