Rapid Single-Cell Detection of Beer-Contaminating Lactic Acid Bacteria Using Bioluminescence/Rapid Microbe Detection.

The rapid microbe detection (RMD) method can detect a trace amount of adenosine triphosphate (ATP) equivalent to that generated by single cell of lactic acid bacteria (LAB). For the improved detection of LAB contamination in beer without cultivation, it is necessary to eliminate the influence of beer-derived ATP and to improve the signal-to-noise ratio. In this protocol, the beer sample is filtered using a membrane filter, thereby avoiding the formation of beer foam to the fullest extent. By washing the beer components remaining on the filter with an ethanol solution and a weakly alkaline solution and then culturing the filter in an agar medium, the beer-derived ATP remaining on the filter can be removed and the ATP of LAB cells is increased. As a result, the signal-to-noise ratio of the RMD method can be dramatically improved.