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Dairy product preservation has evolved over thousands of years and has been a major benefit to humanity by creating stable, nutrient-dense food sources. Today the lactic acid bacteria Lactobacillus reuteri is important in preserving fermented dairy products through the production of the compound reuterin. Reuterin (1,3-propanediol) demonstrates antibiotic properties that prevent the fermentation of dairy products by undesirable bacteria. The purpose of this study is to determine if L. reuteri can produce 1,3-propanediol from a variety of carbon sources. Bacterial strains were incubated in the presence of a carbon source with vitamin B-12 or without B-12 for seven days with samples taken on days 0,1 and 7. Substrate carbon sources included 1,2-propanediol, lactate, hydroxyacetone, acetone, and glycerol. GC-MS is an effective method to identify compounds for metabolomic analysis however it requires that the analytes be volatile. Trimethylsilylation was used to achieve necessary volatility by replacing acidic protons in carboxylic acids, amines, thiols, and hydroxides with a trimethylsilyl (TMS) group. The samples were mixed with ribitol as an internal standard and a mixture of acetonitrile, isopropanol, and water. To achieve silylation samples were derivatized with methoxamine hydrochloride in pyridine followed with N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA). Fatty acid methyl esters were also added as an internal standard and the samples were then submitted to the GC-MS. A method for analyte identification was developed by comparing reference indices and mass spectral data to AMDIS and Shimadzu GC-MS libraries. This method was then used on all samples to detect changes in metabolite presence. The data will ascertain under what conditions L. reuteri can produce the antibiotic compound 1,3-propanediol. This information will allow producers to better preserve dairy products consequently increasing shelf life and food safety.

Publication Date



Logan, UT


dairy preservation, B-12, stable food sources, food safety



The Effects of Various Carbon Sources and the Presence of Vitamin B-12 on the Production of 1,3-propanediol by <em>L. reuteri.</em>

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