lactic acid bacteria, acetic acid bacteria, cherry wine, malolactic fermentation, wine spoilage
Cell Biology | Microbiology | Molecular Biology
Henk, Emily; Dietrich, Margaret; and Weese, Terri, "Identification of Lactic Acid Bacteria in Michigan Cherry Wines" (2008). Student Summer Scholars. Paper 2.
Many factors contribute to the final flavor of wine. One factor is malolactic fermentation, during which lactic acid bacteria (LAB) transform the harsh tasting malic acid into a more drinkable lactic acid in grape wine. The role of LAB in the production of cherry wine is completely unknown. The goal of this study is to identify the species of LAB in cherry wine and compare them to those found in grape wines. Bacteria from cherry wine were grown on general media plates and plates fortified with malic acid, which may provide optimal growing conditions for the LAB. To identify the bacteria, we use PCR to isolate 16S ribosomal DNA sequences, which encode a general gene found in all bacteria. We then use nested PCR to narrow our focus on a specific variable region of the gene; this differentiates the DNA of different LAB after sequencing. Sequences of the variable region will be entered into an online database, which will allow us to identify the bacteria. We were able to isolate 62 colonies from two different wine samples and 18 are ready for nested PCR. Preliminary sequence analysis of earlier colonies allowed the identification of the genus, but not the species. In order to properly identify the bacteria, other identification tests will be used: catalase testing, Gram staining, identification of shape. By identifying LAB in cherry wine, winemakers may be able to determine how to use LAB to enhance the final flavor of wine and discourage growth that contributes to spoilage of wine.