PCR-based DGGE fingerprinting and identification of the microbial population in South African red grape must and wine

Abstract

Aim: The aim of this study was to evaluate the microbial population present in red grape must and wine using polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE). Methods and results: Red wine from the cultivars Pinotage and Merlot were produced and samples taken throughout alcoholic and malolactic fermentation (MLF). PCR fragments were resolved by DGGE and unique fingerprints were obtained for the bacteria and yeasts present in the wines. Lactobacillus plantarum, Enterobacter sakazakii (Cronobacter sp.) and Pantoea agglomerans were present in the Pinotage during both alcoholic and MLF, and in both inoculated and spontaneous fermentations. E. sakazakii (Cronobacter sp.) and P. agglomerans were also observed in the Merlot wines during alcoholic fermentation as well as MLF. Saccharomyces cerevisiae was the most dominant yeast observed in Pinotage, and was the only yeast observed in Merlot. This yeast was observed until the end of MLF. Conclusions: Results showed that the microbial flora that participates in the winemaking process is more diverse than commonly thought. Significance and impact of the study: This method may serve as an alternative to conventional microbiological methods for the identification of the microbial species in red grape must and wine.

Keywords

• red wine
• alcoholic fermentation
• malolactic fermentation
• Enterobacter sakazakii (Cronobacter sp.)
• Pantoea agglomerans