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Inhibition of Pseudomonas species by hydrogen peroxide producing Lactobacilli Public Deposited

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  • Eighty-one microbial species isolated from seafoods and other marine sources were examined to determine the extent of interactions among these species. Spot-plates, cross-plates, and concurrent growth experiments at 7, 15, 20, and 30 C indicated that Lactobacillus species were capable of inhibiting other microorganisms. Lactobacillus species isolated from oysters and identified as L. plantarum produced a substance inhibitory to Pseudomonas, Bacillus, and Proteus species, the most sensitive being Pseudomonas. The inhibitory substance accumulated in Lactobacillus culture media, reaching maximum concentrations in 4 to 5 days at 30 C. The active substance was dialyzable, heat labile, and inactivated by catalase. Inhibitor production paralleled H₂O₂ production in Lactobacillus cultures, further indicating that the observed inhibition was due to H₂O₂ produced by lactobacilli. These findings may explain the abnormal microbial flora shifts observed in foods where Lactobacillus species have overgrown the natural flora.
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  • On envelope: "Robert James Price. Paper in lieu of thesis for M.S. degree 1969"



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