Presenter: Kayden Stevenson
Authors: Kayden Stevenson, Taylor Oberg, Dallin Leatham
Faculty Advisor: Robert Ward
Institution: Utah State University
Dairy food preservation has evolved over time through the use of lactic acid bacteria (LAB) cultures to ferment lactose into lactate. Recently, LAB cultures have been identified which produce antimicrobial compounds that inhibit the growth of spoilage and pathogenic organisms. Latilactobacillus curvatus has recently been identified as a major organism in aged cheddar cheese, and the potential to make antimicrobial products have been identified through whole-genome sequencing. These products include propionate, 3-hydroxypropionate, and the intermediate 3-hydroxypropionaldehyde, which constitutes parts of the antimicrobial reuterin, which has been well studied for its antimicrobial properties. This potential ability in Lat. curvatus is unique. The purpose of this study is to determine the metabolic capabilities of Lat. curvatus when grown on different substrates. Bacterial strains were incubated anaerobically using different carbon sources with and without vitamin B-12 for seven days. Samples were taken on days 0, 1 and 7. Substrates included 1,2-propanediol, lactate, and glycerol. GC-MS was used to identify metabolomic compounds. Briefly, the 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 analyzed on the GC-MS. Analytes were identified by comparing reference indices and mass spectral data to AMDIS and Shimadzu GC-MS libraries. The data shows that Lat. curvatus can produce propionate from 1,2-propanediol, but not from lactate. This shows that the organism is missing the ability to convert lactate to 1,2 propanediol. the data also shows that Lat. curvatus can produce 3-hydroxypropionate from glycerol, and that the amount dramatically increases when B-12 is added. This shows the potential use of Lat. curvatus as a protective adjunct culture to decrease spoilage and potentially inhibit pathogenic organism growth in fermented dairy products.