식품에 존재하는 병원균을 신속검출하기 위한 방법으로 LAMP와 real-time PCR 방법을 비교 평가 하였다. S. Typhimurium, L. monocytogenes, C. sakazakii의 3종에 대해 식품공전에서 권고하는 식품 종류를 선별하여 민감도를 분석하였다. S. Typhimurium에서는 11종의 식품(햄, 닭가슴살, 계란, 돼지고기, 소고기, 오리고기, 액상음료, 샐러드, 콘프레이크, 초콜릿, 사료)중 4종(햄, 돼지고기, 시리얼, 사료)에서 LAMP보다 real-time PCR에서 검출 민감도가 10 배 이상 더 높았고, 6종(닭가슴살, 계란, 소고기, 오리고기, 음료, 샐러드)에서는 real-time PCR과 비슷한 수준을 그리고 초콜릿에서는 real-time PCR로는 검출되지 않았으며 LAMP로만 검출되는 결과가 나타났다. L. monocytogenes 와 C. sakazakii에서는 9종 모두에서 LAMP보다 real-time PCR에서 검출 민감도가 더 높았다. 또한 L. monocytogenes 에서 LAMP의 검출 민감도가 S. Typhimurium과 C. sakazakii 보다 10배 이상 낮았다. 3M MDS의 검출한계 향상을 위해 변형된 3M MDS의 민감도는 기존대비 10배 이상 증가되었다. 따라서 식품에 존재하는 병원균의 검출 을 위해 식품의 구성성분에 따라 LAMP와 real-time PCR 를 적절히 선택하는 것이 바람직할 것으로 생각되었다. 한편, 농축 방법을 이용해 LAMP방법의 민감도를 향상시킬 수 있음을 알 수 있었다.

Cronobactersakazakii is a newly emerging high hazard pathogen, which causes encephalomeningitis and necrotic colitis. Recently, successful biocontrol of harmful microorganisms in several foods through the use of bacteriophages has been reported. In this study, bacteriophages were isolated from kimchi and sewages. Morphological analysis by TEM indicated that phages belonged to the Myoviridae family. In case of heat stability, KCES2 and ESP 2949-2 phages were susceptible to temperatures above 70oC. KCES2 and ESP 2949-2 phages inhibited the growth of C. sakazakii in culture broth. When KCES2 and ESP 2949-2 phages were applied to biofilm-formed C. sakazakii, C. sakazakii was efficiently reduced. Therefore, newly isolated KCES2 and ESP 2949-2 phage for C. sakazakii might effectively reduce C. sakazakii in various foods.

Real-time PCR could help to provide answers to urgent questions about the incidence, prevalence, and epidemiology of currently emerging food-borne bacteria and diseases as identification and detection tools. The objective of this study was carried out to examine several critical parameters that must be optimized when converting from the ABI Prism 7000 SDS platform to the Cepheid SmartCycler Ⅱ so as to directly use the same primer and probe sequences. A lyophilized master mix-OmniMix HS bead, MgCl2 concentration, and PCR cycling conditions were evaluated so as to convert to a new platform, Smartcycler Ⅱ. The best optimal cycling conditions to detect Cronobacter sakazakii on SmartCycler Ⅱ were as follow: initial denaturation at 95℃ for 2 min followed by 45 cycles of 95℃ for 15 s, and 60℃ for 60 s using OmniMix HS bead contained 6 mM MgCl2 concentration. And the Ct value was 16.97 compared to 23.84 of Ct value in ABI Prism 7000 SDS. This result showed that when the several analytical parameters were taken the consideration for optimization, it could be performed assays between real-time PCR platforms. Also it is need of further study to develop the new single multiplex real-time PCR method for determining various Cronobacter spp. including three subspecies, too.

The objectives of this study were to compare the biochemical profiles with biogroups for the identification of Cronobacter spp. (formally known as Enterobacter sakazakii) isolates using biochemical identification kits. A total of 38 Cronobacter spp. contained 5 clinical, 31 food, and 2 environmental isolates were used. All isolates were identified as Cronobacter spp. with the Vitek II system and ID 32E kit. The API 20E kit identified all isolates as Cronobacter spp. but the percentage identification was 51.1% for 16 of 38 isolates. These strains were contained to Biogroup 2, 9, 10, and 11. The utilization of inositol is a factor determining the percentage identification of Cronobacter spp. with the API 20E kit.

C. sakazakii ATCC 12868, 29004, 29544를 이용하여 저온 저장 중의 변화를 살펴보고 저온과 냉/해동, 저온과 산, 저온에서 starvation한 것과 냉/해동의 교차저항에 대해 알아보았다. C. sakazakii를 에서 10일간 저장하였을 때 모든 균주들에서 1 log CFU/mL의 사멸을 보였다. C. sakazakii를 에서 배양한 결과, C. sakazakii ATCC 12868, 29004는 각각 7일째, 5일째