29F-2 |
Antimicrobial activity of Lactobacillus reuteri against Escherichia coli O157:H7 |
M. M. SALAMEH1, S. A. Ibrahim1, C. W. Seo1, and A. Shahbazi2. (1) Food Science and Nutrition, North Carolina A&T State University, Greensboro, NC 27411-1064, (2) Dept. of Agricultural & Biosystems Engineering, North Carolina A&T State Univ., Greensboro, NC 27411-1064 Lactobacillus reuteri (L. reuteri) is known to produce a broad-spectrum antimicrobial compound, reuterin. The antimicrobial spectrum of reuterin includes Gram positive and Gram negative bacteria. The purpose of this study was to determine the antimicrobial activity of L. reuteri against foodborne pathogen, Escherichia coli O157:H7. Five different strains of L. reuteri were incubated at 37° C for 24 hr in two different growth media (MRS without glycerol, and MRS with 0.2M glycerol solution). Samples were centrifuged (5,000g, 15 min) to obtain supernatants which were then tested against five strains of E. coli O157:H7 using LB broth. E. coli O157:H7 growth was monitored by measuring turbidity at 610 nm in a spectrophotometer at different time intervals during incubation at 37° C for 8 hours. Results show that L. reuteri has the ability to produce antimicrobial compound against E. coli O157:H7 only in the presence of glycerol. Such inhibition could not be observed when L. reuteri was grown in MRS without glycerol. Two strains of L. reuteri showed total growth inhibition against the foodborne pathogen. The growth inhibition could be observed within 4hr in LB broth. The growth inhibition was observed before the end of the exponential phase. The activity of L. reuteri against E. coli O157:H7 was confirmed using agar diffusion assay. These results suggest potential application of L. reuteri as natural biopreservative to control growth of E. coli O157:H7 and ensure the safety of our foods.
Session 29F, Food Microbiology: Control of foodborne microorganisms by antimicrobials
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