Restoration of culturability of starvation-stressed and low-temperature-stressed Escherichia coli O157 cells by using H2O2-degrading compounds.
Late-exponential-phase cells of Escherichia coli O157:H- strain E32511/HSC became nonculturable in sterilized distilled water microcosms at 4 degrees C. Plate counts declined from 3 x 10(6) to less than 0.1 CFU/ml in about 21 days. However, when samples of microcosms at 21 days were inoculated onto an agar medium amended with catalase or nonenzyme peroxide-degrading compounds such as sodium pyruvate or alpha-ketoglutaric acid, plate counts increased to 10(4)-10(5) CFU/ml within 48 h. The proposed mode of action of the catalase or pyruvate is via the degradation of the metabolic by-product H2O2, rather than through supplementation of a required nutrient in the recovery of nonculturable cells. Our studies were based on the assumption that E32511/HSC strain responds to starvation and a low temperature by entering a nonculturable state and that the correction of oxidative stress upon the inoculation of bacteria on agar plates promotes recovery of nonculturable cells.
Department of Bacteriology, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan.
Y
Y
Mizunoe
S N
SN
Wai
A
A
Takade
S
S
Yoshida
D002374:Catalase; D003080:Cold Temperature; D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D019453:Escherichia coli O157 / Q000254:growth & development* / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007656:Ketoglutaric Acids; D011773:Pyruvates
D003470:Culture Media; D007656:Ketoglutaric Acids; D011773:Pyruvates; D006861:Hydrogen Peroxide; D002374:Catalase