The screening of hydrogen peroxide-producing lactic acid bacteria and their application to inactivating psychrotrophic food-borne pathogens.
Lactic acid bacteria were isolated from various food samples and evaluated for hydrogen peroxide (H2O2) production. Cells suspended in 0.5% (wt/vol) glucose plus 0.5% (wt/vol) lactate (pH 7.0) were incubated for 5 h at 37 degrees C under aeration. Among 193 strains, 27 strains accumulated 201-300 ppm H2O2, and 4 strains accumulated more than 301 ppm H2O2 in the cell suspensions. Among the 9 high-level H2O2-producing strains, 8 strains were identified as Lactococcus lactis subsp. lactis. The cell-free filtrate from Lc. lactis subsp. lactis AI 62, which contained approximately 350 ppm H2O2, was evaluated for antimicrobial activity against Enterococcus faecalis, Ent. faecium, enterotoxigenic Escherichia coli, Listeria ivanovii, Staphylococcus aureus, Yersinia enterocolitica, and Aeromonas hydrophila. After 1 h incubation at 30 degrees C in the cell-free filtrate, the initial viable cell counts of the target bacteria (5.53-6.00 log cfu/mL) were reduced by 0.12-5.00 log units, except in the case of enterococci. The sensitivity varied with the bacterial species and pH. The enterococci were resistant to the treatment. Our results show that H2O2 accumulated by lactic acid bacteria in a cell suspension is very effective in reducing the viable cell count of food-borne pathogens.
Department of Biochemistry and Biotechnology, Faculty of Agriculture and Life Science, Hirosaki University, Bunkyocho 3, 036-8561 Hirosaki, Japan.
Ayano
A
Ito
Yuki
Y
Sato
Syoko
S
Kudo
Susumu
S
Sato
Hajime
H
Nakajima
Takahiro
T
Toba
D016980:Aeromonas hydrophila / Q000187:drug effects / Q000254:growth & development; D001419:Bacteria / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D015169:Colony Count, Microbial; D003470:Culture Media; D013293:Enterococcus faecalis / Q000187:drug effects / Q000254:growth & development; D016984:Enterococcus faecium / Q000187:drug effects / Q000254:growth & development; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005374:Filtration; D005516:Food Microbiology; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism; D013294:Lactococcus lactis / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism; D008087:Listeria / Q000187:drug effects / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D015008:Yersinia enterocolitica / Q000187:drug effects / Q000254:growth & development
D003470:Culture Media; D006861:Hydrogen Peroxide