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A De-lactose Whey Fermentate Food Ingredient with Very Broad-spectrum Antimicrobial Properties

Investigators
O'Sullivan, Daniel J
Institutions
University of Minnesota
Start date
2009
End date
2010
Objective
1. Evaluate if production in broth can be achieved by adding crude lantibiotic to increase signal transduction. 2. Evaluate a classical mutagenesis approach to optimize lantibiotic production. 3. Determine the range of the antimicrobial activity of this lantibiotic. 4. Produce a de-lactose whey fermentate powder using this culture.
More information
The objective of this exploratory project was to develop a whey-based fermentate that contains probiotic lantibiotic-producing bifidobacteria. The fermentate would be spray dried into a powder and used as a food ingredient to protect against prominent food pathogens such as E. coli and Salmonella. A lantibiotic is a modified protein with broad-spectrum antimicrobial activities. The only commercially available products that have broad-spectrum antimicrobial activities are those that inhibit gram-positive bacteria, not gram-negative bacteria such as E. coli and Salmonella. Researchers previously discovered a probiotic bifidobacterium called Bifidobacterium longum subsp. longum (DJO10A) that produces this lantibiotic compound, but only on solid media (agar), not in liquid medium. The results of this study show that the lantibiotic gene cluster could be switched on in broth in a dose dependant fashion, up to the maximum level of added inducer of 160 AU. To maintain expression of the gene cluster, the culture could be sub-inoculated at a minimum of 10% to maintain sufficient levels of the induced in the medium. Researchers were unable to detect the lantibiotic compound in the supernatant, but detected a 3.2 kDa lantibiotic peptide in the pellet using Maldi-Tof MS. The obtained mutants and grew them in the presence of 250 AU/ml of a crude lantibiotic preparation. Researchers determined that none of the mutants significantly increased lantibiotic production. An antimicrobial spectrum analysis of this crude lantibiotic preparation revealed a broad spectrum of both gram-positive and gram- negative bacteria, illustrating its potential usefulness as a natural food preservative. This exploratory project demonstrated that the broad-spectrum lantibiotic of B. longum DJO10A could be produced in broth cultures. In order to achieve a whey-based fermentate with the lantibiotic-producing B. longum DJO10A, more research is needed to optimize production the lantibiotic in broth cultures.
Funding Source
Dairy Research Inst.
Categories
Chemical Contaminants
Salmonella
Escherichia coli
Bacterial Pathogens