Enhancing Hydrogen Peroxide Formation by Lactobacillus Delbrueckii Str Resistant Mutants in The Cold Condition
Publish Year: 1395
نوع سند: مقاله کنفرانسی
زبان: English
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شناسه ملی سند علمی:
BSCONF03_104
تاریخ نمایه سازی: 6 اسفند 1395
Abstract:
The strains of Lactobacillus delbrueckii subsp. lactis widely used in food preservation due to ability produce high amount of hydrogen peroxide at refrigerator temperatures to inhibit food-borne pathogens and psychrophilic spoilage microorganisms. In order to improve of bio-preservation efficacy of L. delbrueckii MDC 9617 mutations causing resistance to streptomycin (str) were used. Among UV-mutagenized population of L. delbrueckii three str mutants producing high amounts of H2O2 were selected. Str mutants produced significant amounts of hydrogen peroxide 50-60 μg/ml in sodium phosphate buffer (0.2 M, pH 6.5) and in beef broth (BB) at 5 °C for 5 days submerged cultivation without of growth. Evaluation mutants antibacterial activity at refrigeration temperatures against food-borne pathogen Escherichia coli O157: H7 revealed elimination of pathogen total number up to practically undetectable amount for 3 days. In case of solid-state cultivation on agar-based medium, disks soaked by mutant cells suspensions formed2larger inhibitory zones on E. coli O157: H7 lawn for one-day cold exposition. The size of inhibition zone depends on concentration of LAB cells. Str mutants L. delbrueckii reduced initial amount 2×105 of E. coli O157: H7 in ground beef up to 3 log for 3 days of solid-state cocultivation when the wild strain reduced only 2 log. The application of L. delbrueckii mutants did not cause any changes in sensory characteristics of ground beef, moreover promotes expanding of shelf-life due to inhibition of psychrophilic spoilage microorganisms.
Keywords:
Biopreservation , Lactobacillus delbrueckii , Str mutations , refrigerated temperatures , hydrogen peroxide , E. coli O157: H7
Authors
Alireza Goodarzi
Armbiotechnology Scientific and Production Center NAS RA, Yerevan, Armenia
Vahid Goodarzi
Department of microbiology, Islamic Azad University, Arak branch.
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