P7: Combining an Immunomagnetic Separation Technique with a Multiplex PCR Method for the Detection of Beer Spoilage Lactic Acid Bacteria

For the brewing industry, the possibility of beer spoilage by lactic acid bacteria (LAB) or by wild yeasts is always a concern. Contamination by certain LAB, such as Lactobacillus brevis, L. casei, L. plantarum, Pediococcus claussenii, P. damnosus, and P. inopinatus, may result in the deterioration of beer quality. Thus, monitoring of these spoilage organisms during the brewing process is critical to quality control. When concentrations of spoilage organisms in the brewing samples are low, and thus difficult to detect, collection and concentration of these spoilage organisms prior to the application of diagnostic methods are important. Although the membrane filtration method can be used, it is possible that some LAB cells will go through the membrane filters. Also, membrane fouling may restrict the beer volume to be filtered. In this study, polyclonal antibodies against beer spoilage bacteria were  prepared by rabbit immunization. The antibodies were then conjugated to magnetic  beads for the capture and concentration of major beer spoilage LAB. The captured  cells were subsequently discriminated to species level by a multiplex polymerase chain reaction (mPCR) method we designed. Such approach allowed the simultaneous and sensitive detection of several  major beer spoilage LAB species in the brewing samples within 8 h. This method is accurate, time-saving and can be used for routine monitoring and control of the  spoilage organisms during the beer brewing process.