Rapid identification of pickle yeasts by fluorescent PCR and microtemperature-gradient gel electrophoresis

Monitoring the yeast populations within pickle soaking fluid is imperative for ensuring optimum taste, but these analyses have proven time-consuming and expensive, limiting their industrial application. Here, yeasts were identified in the soaking fluid from Japanese radish pickles using fluorescent PCR amplification of the variable D1/D2 region of the 26S rDNA, followed by analysis with microtemperature-gradient gel electrophoresis (μ-TGGE). This smaller version of the normal TGGE apparatus is capable of analyzing samples 10- to 20-fold faster without sacrificing data quality. Each primer set was labeled with a different fluorescent dye, allowing easy isolation of the various PCR products and identification of the bands corresponding to the various yeasts. The results indicate that fluorescent PCR and μ-TGGE may be a useful new method for rapid, easy monitoring of yeast flora in various food industries. This new method can be used on a daily basis to provide overviews of yeast flora during pickle production, allowing producers to quickly grasp pickle readiness at a single glance.