Purification and partial characterization of an antigen specific to Lactobacillus brevis strains with beer spoilage activity

Abstract

Certain Lactobacillus brevis strains are resistant to hop-derived compounds such as isohumulone and are able to grow in beer. In this study, we raised an antiserum against our beer spoilage laboratory strain L. brevis 578 which reacted with 23 of 24 beer spoilers and two of 13 non-spoilers in precipitation reactions using 0.5 M NaOH cell extracts. This specific antigen to the beer spoilage L. brevis strains (SABSL) was demonstrated to be located beneath the S-layer proteins by agglutination reactions using S-layer protein-stripped cells obtained by treatment with 0.1 M NaOH. SABSL was purified using an affinity column coupled with an antibody against SABSL. The purified antigen was hydrolyzed with 2 M HCl and the hydrolyzate was analyzed by thin-layer chromatography and enzymatic analysis. The results showed that SABSL contains glycerol, phosphate, glycerophosphate, d-galactose and d-glucose. d-Galactose and d-glucose accounted for 4.7% and 0.1% of the composition, respectively. Melibiose, but not mannose, inhibited the precipitation reaction. Intense precipitation reactions were obtained with fractions which did not bind to the ConA-column. These results indicate that the immunodominant component of the SABSL is galactose and the SABSL determinant is most probably a galactosylated glycerol teichoic acid. The antiserum raised against the beer spoilage strain L. brevis 578 could distinguish between Pediococcus beer spoilers and non-spoilers in precipitation reactions.