Detection of Pediococcus spp. in brewing yeast by a rapid immunoassay

Abstract

A membrane immunofluorescent-antibody test was developed to detect diacetyl-producing Pediococcus contaminants in brewery pitching yeast (yeast [Saccharomyces cerevisiae] slurry collected for reinoculation). Centrifugations at 11 and 5,100 x g separate yeast cells from bacteria and concentrate the bacteria, respectively. Pelieted bacteria resuspended and trapped on a black membrane filter are reacted with monoclonal antibodies specific for cell surface antigens and then with fluorescein-conjugated indicator antibodies. Whether pitching yeast is contaminated with pediococci at 0.001% is determined in <4 h. The sensitivity of the assay is 2 orders of magnitude below the Pediococcus detection limit of direct microscopy.

Imaging of Lactobacillus brevis single cells and microcolonies without a microscope by an ultrasensitive chemiluminescent enzyme immunoassay with a photon-counting television camera

“…The detection limit of our CLEIA method was approximately 20 L. brevis cells in 633 ml of beer and is good compared to those of the numerous rapid detection methods that have been reported (2,4,21,25). Moreover, the procedure is relatively simple, and a period of only 4 h is required for this CLEIA (15 min for the concentration of L. brevis on the membrane, 3.5 h for dilute alkali treatment of cells and antigenantibody reaction, and 15 min for detection and quantification).…”

“…There is a special need for the development of new rapid microbial detection methods for medical diagnosis and the food industry. Existing rapid methods include the direct epifluorescent filter technique (10), microcolony epifluorescence microscopy (13), the filter fluorescent antibody technique (3,21), PCR (17,19), ATP photometry (4), enzyme immunoassay (EIA) (1), and the lux gene recombinant bacteriophage technique (15).…”

The changing face of microbial quality control practices in the brewing industry: Introducing mass spectrometry proteomic fingerprinting for microbial identification

“…Subsequently the identity of the organism can be determined by sequencing the amplified product and matching against a database of known ITS sequences. [Colour figure can be viewed at wileyonlinelibrary.com] 110 mL filtered beer) (51-53), concerns regarding result variability, particularly at low levels of contamination, have prevented the adoption of this method for routine analyses in breweries (54).…”

Enrichment Cultivation of Beer-Spoiling Lactic Acid Bacteria

“…However, the membrane filtration of brewery samples may cause false negative results in detection, due to the passing of bacteria that have changed their morphology during adaptation to the environment 8 . Samples containing high concentrations of yeast cells cannot be filtered, and currently the most effective technique for their pre-processing is differential centrifugation 104 . Co-flocculation of bacteria with sample components or yeast in differential centrifugation has been reported 61,77 .…”