Survival of Acid Adapted Escherichia coli O157:H7 in Some Acidic Foods (in English)

Öz

This study examined the effect of adaptation to acid on the survival of Escherichia coli O157:H7 in Ayran, turnip juice, apple juice and orange juice.E. coli O157:H7 was adapted to acid at pH 4.5 in tryptic soy broth (TSB) for 2 h. Commercial products of Ayran (pH 3.95), turnip juice (pH 3.6), orange juice (pH 3.0) and apple juice (pH 3.3) were inoculated with acid adapted or nonadapted cells of E. coli O157:H7. Survival of the inoculated E. coli O157:H7 in these commercial food products during storage periods was examined. Orange juice, apple juice and turnip juice were stored at 4 °C or 20 °C. Ayran was stored at 4 °C. In general, low temperature enhanced the survival of E. coli O157:H7 in the commercial juices tested (p<0.05). Acid adaptation enhanced the survival of E. coli O157:H7 in turnip juice and apple juice stored at 4°C. It was found that survival of the acid adapted and nonadapted E. coli O157:H7 in orange juice during storage at 4 °C or 20 °C and Ayran during storage at 4 °C did not show any significant differences (p<0.05). This study showed that adaptation to acid might increase survival of E. coli O157:H7 in some acidic foods. Therefore acid adaptation is an important mechanism in E. coli O157:H7 and should be considered in food challenges studies.

Anahtar Kelimeler

• E. coli O157:H7, acidic foods, acid adaptation.   

Aside Adapte Edilen Escherichia coli O157:H7'nin Bazı Asidik Gıdalardaki Canlılığı (İngilizce)

Öz

Bu çalışmada Escherichia coli O157:H7'ninaside adaptasyonunun Ayran, şalgam suyu, elma suyu ve portakal suyundaki canlılığına etkisi araştırılmıştır.Escherichia coli O157:H7 pH 4,5'te Tryptic Soy Broth besiyerinde 2 saat tutularak aside adapte edilmiştir. Ticari olarak satılan Ayran (pH 3,95), şalgam suyu (pH 3,6), portakal suyu (pH 3,0) ve elma suyu (pH 3,3) aside adapte edilen ve edilmeyen Escherichia coli O157:H7 kültürü ile inoküle edilmiştir. Bu ürünlerde inkübasyon süresince Escherichia coli O157:H7'nin canlılığı saptanmıştır. Elma, portakal ve şalgam suyu 4 °C ve 20 °C'de depolanırken Ayran yalnızca 4 °C'de depolanmıştır. Genel olarak aside adaptasyondan bağımsız olarak düşük sıcaklık, test edilen tüm örneklerde Escherichia coli O157:H7'nin canlılığını artırmıştır. Aside adaptasyon 4 °C'de depolanan şalgam suyunda Escherichia coli O157:H7'nin canlılığını artırmıştır (p<0,05). Ayrıca aside adaptasyon 4 °C'de depolanan elma suyunda da Escherichia coli O157:H7'nin canlılığını artırmıştır ancak bu etki istatistiksel olarak önemli bulunmamıştır (p<0,05). 4 °C ve 20 °C'de depolanan portakal suyu ve 4 °C'de depolanan elma suyunda ise aside adapte edilen ve edilmeyen Escherichia coli O157:H7 kültürlerinin canlılıkları arasında önemli bir fark tespit edilememiştir. Bu çalışma Escherichia coli O157:H7'nin asidik gıdalarda uzun süre canlı kalabileceğini ve aside adaptasyonun bazı asidik gıdalarda bu patojenin canlılığını artırdığını göstermiştir. Sonuç olarak aside adaptasyon Escherichia coli O157:H7'nin asidik gıdalarda canlı kalmasını sağlayan önemli bir mekanizma olup gıda güvenliği çalışmalarında mutlaka göz önüne alınmalıdır.

Anahtar Kelimeler

• E. coli O157:H7, asidik gıdalar, aside adaptasyon.

Kaynakça

1. Padhye NV. Doyle MR. 1992. Escherichia coli 0157:H7: Epidemiology, pathogenesis and methods for detection in food. J Food Protect, 55: 555-565.
2. Griffin PM, Tauxe HV. 1991. The epidemiology of inlections caused by Escherichia coli 0157:H7, other enterohemorrhagic E. coli and the associated hemolytic uremic syndrome. Epidemic Rev, 13: 60-97.
3. Anonymous 1997. Report of WHO consultation on prevention and control of enterohaemorrhagic Escherichia coli (EHEC) infections. WHOIFSF/FOSI 97.6 WHO report. Geneva. Switzerland.
4. Buchanan FlL. Edelson RL. 1999. pH Dependent stationary phase acid resistance response of enterohaemorrhagic Escherichia coli in the presence of various acidulant. J Food Protect, 62: 211—218.
5. R.TOSUN - Ş..—LGÖNÜL 273
6. Leenanon B, Drake MA. 2001. Acid stress, starvation and cold stress affect post stress behaviour of Escherichia coli
7. Leyer GJ, Wang L, Johnson EA. 1995. Acid adaptation of Escherichia coli0157zH7 increases survival in acidic foods.
8. Tosun H, Gönül ŞA. 2003. Acid tolerance response of some pathogen bacteria and its importance in load industry. PhD

9. Hsln— Yi C, Chou C. 20.01. Acid adaptation and temperature effect on the survival of Escherichia coli 01 57:H7 in acidic
10. Gahan CGM, O'driscoll B, Hill C. 1996. Acid adaptation of Listeria monocytogenes can enhance survival in acidic foods
11. Beuchat LR, Brackett RE, Doyle MP. 1994. Lethality of carrotjuice to Listeria monocytogenes as affected by pH. sodium
12. Tsai Y, Ingham SC. 1997. Survival of Escherichia coli 0157: H7 and Salmonella spp. in acidic condiments. J of Food
13. ‘5. Miller LG, Kaspar CW. 1994. Escherichia coli 0157:H7 acid tolerance and survival in apple cider. J Food Protect, 57:
14. Steele BT, Murphy N, Rance CP. 1982. An outbreak of hemolytic uremic syndrome associated with ingestion of fresh
15. Zhao T, Doyle MP, Besser HE. 1993. F_ate of enterohaemorrhagic Escherichia coli 0157: H7 in apple cider with and
16. without preservatives. Appl and Environ Microbiol, 59. 2526— 2530.
17. Ftyu JH, Beuchat LR. 1998. Influence of acid tolerance responses on survival, growth, and thermal cross— protection of
18. Escherichia coli 0157:H7 in acidilied media and fruit iuices. Int J Food Microbiol, 45:185-193.
19. Parish ME, Narciso JA, Friedrich LM. 1997. Survival of Salmonella in orange juice. J Food Safety, 17: 273—281.
20. Singh BFt, Kulshreshtha SB, Kapoor KN. 1996. An orange juice-borne outbreak due to enterotoxigenic Escherichia coli.
21. Borczyk AA, Karmali MA, Loir H, Duncan LMC. 1998. Bovine reservoir for verotoxin producing Escherichia coli 0157:H7. Lancet. '
22. Clarke FIC, McEwen VP, Gannon H, Lior H, Gyles CL. 1989. Isolation of verocytoxin- producing Escherichia coli from
23. milk filters in south-western Ontario. Epidemiol and Infect, 102: 253-260.
24. Morgan D, Newman CD. Hutchinson DN. Walker AM. Rowe B, Majid _F. 1993. Verotoxin producing Escherichia coli
25. :H7 infection associated with the consumption of yoghurt. Epidemiol and Infect, 111: 181—167.
26. Halkman AK, Noveir MP, Doğan HB. 2001. Escherichia coli0157zH7 serotipi. Sim Matbaacılık Ltd. Şti., Ankara, 435.