A new and rapid method for determination of beer-spoilage ability of lactobacilli

A new method for determining the capability of beer-spoilage by lactobacilli was developed. This method is based on the sequence of a hop possible-resistance gene, designated horA (l,749base), which was identified on a plasmid of hop-resistant Lactobacillus brevis ABBC45. A pair of primers were designed based on the partial sequence of horA. We examined various Lactobacillus species for the presence of horA-like gene by polymerase chain reaction (PCR) using these primers. The amplification of specific DNA fragments, which suggests the presence of horA-like gene, occurred almost exclusively in the beer-spoilage lactobacilli regardless of their species. This method makes it possible to determine the capability of beer-spoiling character of lactobacilli rapidly, without taxonomic identification and the cultivation in beer or hop containing media.