Sodium chloride decreases the bacteriocidal effect of acid pH on Escherichia coli O157:H45

被引:48
作者
Casey, PG [1 ]
Condon, S [1 ]
机构
[1] Natl Univ Ireland Univ Coll Cork, Dept Microbiol, Cork, Ireland
关键词
Escherichia coli O157 : H45; sodium chloride; acid pH; stress interaction; cytoplasmic pH;
D O I
10.1016/S0168-1605(02)00018-1
中图分类号
TS2 [食品工业];
学科分类号
0832 ;
摘要
To reduce the risk of foodborne illness, many fermented and minimally processed foods rely on the ''hurdle effect'', i.e. a combination of two or more inhibitory agents being more inhibitory than any of the agents alone. However, we have observed that such a combination of agents is not always more inhibitory to foodborne pathogens than one alone. In this paper, we show that a combination of NaCl and acid pH is less effective than acid pH alone in reducing the numbers of Escherichia coli O157:H45. The presence of sodium chloride reduces the bacteriocidal effect of lactic acid on logarithmically growing cells of E. coli O157:H45, with approximately 10(3)-fold more survivors at pH(o) 4.2 when 4% NaCl was added to the medium. A similar protective effect was also seen with other organic acidulants and E. coli strains. The cytoplasmic pH (pH(i)) of cells in medium at pH 4.2 containing added salt was 5.8 which was 0.56 units higher than that of cells in the same medium without added salt. When the pHi of cells in medium without added salt was adjusted to the same value (5.8) by adding KOH, the rate of survival was also considerably greater than that of cells in medium without added salt. These data suggest that E. coli can use NaCl to counteract acidification of its cytoplasm by organic acids, and in addition, that combinations of antimicrobial agents cannot always be relied upon to achieve additive antimicrobial effects. (C) 2002 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:199 / 206
页数:8
相关论文
共 34 条
[11]   The ability of Escherichia coli O157:H7 to decrease its intracellular pH and resist the toxicity of acetic acid [J].
DiezGonzalez, F ;
Russell, JB .
MICROBIOLOGY-UK, 1997, 143 :1175-1180
[12]  
Doyle M. P., 1989, Foodborne bacterial pathogens., P235
[13]   ISOLATION OF ESCHERICHIA-COLI O157-H7 FROM RETAIL FRESH MEATS AND POULTRY [J].
DOYLE, MP ;
SCHOENI, JL .
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 1987, 53 (10) :2394-2396
[14]   SUMMARY OF THE INTERNATIONAL-SYMPOSIUM AND WORKSHOP ON INFECTIONS DUE TO VEROCYTOTOXIN (SHIGA-LIKE TOXIN)-PRODUCING ESCHERICHIA-COLI [J].
EDELMAN, R ;
KARMALI, MA ;
FLEMING, PA .
JOURNAL OF INFECTIOUS DISEASES, 1988, 157 (05) :1102-1104
[15]  
Entani E, 1997, Kansenshogaku Zasshi, V71, P451
[16]   Acid tolerance and acid shock response of Escherichia coli O157:H7 and non-O157:H7 isolates provide cross protection to sodium lactate and sodium chloride [J].
Garren, DM ;
Harrison, MA ;
Russell, SM .
JOURNAL OF FOOD PROTECTION, 1998, 61 (02) :158-161
[17]   FATE OF ESCHERICHIA-COLI O157/H7 AS AFFECTED BY PH OR SODIUM-CHLORIDE AND IN FERMENTED, DRY SAUSAGE [J].
GLASS, KA ;
LOEFFELHOLZ, JM ;
FORD, JP ;
DOYLE, MP .
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 1992, 58 (08) :2513-2516
[18]   ILLNESSES ASSOCIATED WITH ESCHERICHIA-COLI O157-H7 INFECTIONS - A BROAD CLINICAL SPECTRUM [J].
GRIFFIN, PM ;
OSTROFF, SM ;
TAUXE, RV ;
GREENE, KD ;
WELLS, JG ;
LEWIS, JH ;
BLAKE, PA .
ANNALS OF INTERNAL MEDICINE, 1988, 109 (09) :705-712
[19]   DEATH OF ENTEROHEMORRHAGIC ESCHERICHIA-COLI O157-H7 IN REAL MAYONNAISE AND REDUCED-CALORIE MAYONNAISE DRESSING AS INFLUENCED BY INITIAL POPULATION AND STORAGE-TEMPERATURE [J].
HATHCOX, AK ;
BEUCHAT, LR ;
DOYLE, MP .
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 1995, 61 (12) :4172-4177
[20]  
Jordan KN, 1999, APPL ENVIRON MICROB, V65, P3048