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.
Mizunoe
Y
Y
Department of Bacteriology, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan.
Wai
S N
SN
Takade
A
A
Yoshida
S
S
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