위합성용액에서 과일주스에 노출한 Non-O157 Shiga Toxin-Producing Escherichia coli의 산 저항성 평가

국문 초록 (Abstract)

다양한 환경에서 분리된 시가독소 생산성 대장균(Shiga toxin-producing E. coli, STEC, n=18)을 초산혼합용액(AAS; 400 mM, pH 3.2, 30°C)에 노출한 후 산 저항성을 측정하였다. 또한, 선정된 4종류의 non-O157:H7 STEC균을 사과주스, 파인애플주스, 오렌지주스, 딸기주스(pH 3.8)에 정봉하여 4°C와 20°C에서 24시간 산 적응시킨 후 위합성용액(SGF, pH 1.5)에서 2시간 동안 생존능력을 평가하였다. Non-O157:H7 STEC를 AAS에 노출했을 때 O111 혈청형의 STEC는 평균 0.12 log CFU/mL 감소하여 다른 혈청형에 비하여 가장 강한 산 저항성을 나타냈고 O157:H7 STEC와 유의적 차이가 없었으며(P>0.05), O26 혈청형의 STEC는 가장 민감한 것으로 나타났다. 반면, AAS에 glutamic acid를 첨가하였을 경우 모든 STEC는 혈청형과 관계없이 초산에 매우 강한 저항성을 나타내었다(P>0.05). SGF에서 생존능력을 측정한 결과, 06E0218(O157:H7)은 다른 non-O157:H7 STEC 균들보다 생존능력이 낮았고 03-4669(O145:NM)가 가장 강한 생존능력을 나타내었다. 한편, 과일주스 중에서는 파인애플주스에 산 적응된 STEC가 SGF에 가장 강한 생존능력을 나타내었다. 4°C의 과일주스에 STEC를 산 적응시켰을 경우 20°C보다 SGF에 대한 생존능력이 현저하게 높았다(P<0.05). 따라서 과일주스에 의한 non-O157:H7 STEC의 산 적응력 증가는 위장관 내 생존율 및 식중독 발생을 높일 수 있으므로 이에 대한 적절한 연구와 안전관리 옵션을 제공할 필요가 있을 것으로 판단된다.

다국어 초록 (Multilingual Abstract)

The objectives of this study were Ⅰ) to compare the acid resistance (AR) of seven non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups, including O26, O45, O103, O111, O121, O145, and O157:H7 STEC isolated from various sources, in 400 mM acetic acid solution (AAS) at pH 3.2 and 30°C for 25 min with or without glutamic acid and Ⅱ) to determine strain survival upon exposure to simulated gastric fluid (SGF, pH 1.5) at 37°C for 2 h after acid adaptation in apple, pineapple, orange, and strawberry juices at pH 3.8, 4°C and 20°C. Results show that the O111 serogroup strains had the strongest AR (0.12 log reduction CFU/mL) which was very similar to that of O157:H7 STEC (P>0.05), compared to other serogroups in AAS without glutamic acid, whereas O26 serogroup strains showed the most sensitive AR. However, there was no significant (P>0.05) difference of AR among seven serogroups in AAS with glutamic acid. In the SGF study, 05-6545 (O45:H2), 08023 (O121:H19), and 03-4669 (O145:NM) strains adapted in fruit juices at 4°C and 20°C displayed enhanced survival with exposure to SGF for 60 min compared to 06E0218 (O157:H7) strains (P<0.05). In addition, 4 STEC strains adapted in pineapple juice at 4°C showed enhanced survival with exposure to SGF for 60 min compared to those strains acid-adapted in the other fruit juices. Generally, adaptation at 4°C in fruit juices resulted in significantly enhanced survival levels compared to acid-adapted at 20°C and non-adapted conditions. The AR caused by adaptation in fruit juices at low temperature may thus increase survival of non-O157 STEC strain in acidic environments such as the gastrointestinal tract. These results suggest that more careful strategies should be provided to protect against risk of foodborne illness by non-O157 STEC.

목차 (Table of Contents)

• ABSTRACT
• 서론
• 재료 및 방법
• 결과 및 고찰
• 요약
• REFERENCES

참고문헌 (Reference)

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