Nucleotide Sequence Identities ofhorAHomologues and Adjacent DNA Regions Identified in Three Species of Beer-Spoilage Lactic Acid Bacteria

Abstract

J. Inst. Brew. 110(4), 276-283, 2004The horA homologues and adjacent DNA regions identified in beer-spoilage Lactobacillus lindneri DSM 20690 T and L. paracollinoides DSM15502 T were examined and compared with the corresponding DNA region of beer-spoilage L. brevis ABBC45, a strain in which the hop-resistance gene horA was originally identified. The PCR analysis suggests ORFB1-B5 regions surrounding horA are conserved in all of the strains. The nucleotide sequence comparison of the conserved DNA regions revealed extremely high levels of identities among the three beer-spoilage strains that are not typical for distinct species. The PCR methods using primers specific to the adjacent ORFs were found to be able to differentiate beer-spoilage Lactobacillus strains from non-spoilers, indicating these ORFs are also useful genetic markers for determining the beer-spoilage ability of lactobacilli. The presence or absence of the adjacent ORFs in 92 bacterial strains was completely identical with that of horA homologues, indicating the ORFB1-B5 regions are generally conserved in beer-spoilage Lactobacillus strains. Taken together, these results suggest the ORFB1-B5 regions have been acquired by beerspoilage lactobacilli through horizontal gene transfer and provide a theoretical basis for applying a trans-species genetic marker such as horA to deal with unencountered species of beerspoilage lactobacilli.

A Review of Hop Resistance in Beer Spoilage Lactic Acid Bacteria

“…This type of beer is representative of beers with standard microbiological stability. Although nine horA-positive strains were recognized as false-positive strains in this investigation, four L. brevis strains and one L. casei strain were able to grow in beers adjusted to pH 4.6, which represent beers with weak microbiological stability 100 . Depending on the types of beers manufactured, these false-positive strains should be considered as spoilage strains.…”

“…It was further shown that a small number of L. paracollinoides strains are able to grow in beer despite the absence of horA homologs, indicating multiple genetic markers are required for the concept of trans-species genetic markers to be practically applied in breweries 100 .…”

“…Depending on the types of beers manufactured, these false-positive strains should be considered as spoilage strains. The remaining strains, L. brevis ABBC4, L. buchneri ABBC219, L. plantarum ABBC87 and L. lindneri DSM 20692 NB , exhibit no beer spoilage ability even in beers with weak microbiological stability 87,100 . The reason for the inconsistency is currently unknown but the horA homologs may not be functionally expressed in these false-positive strains, a feature that cannot be evaluated by the present method.…”

“…As a consequence, the probes specific to horB and horC were unable to detect the presence of horB and horC homologs, even under less stringent hybridization and washing conditions, indicating these two beer spoilage strains are deficient in the homologs of horB and horC 87 . From these studies, it was shown that the presence or absence of horA and horC is highly correlated w er spoilage ability of LAB strains 87,100 . Furthermore the most significant part of these studies was that all the beer spoilage LAB strains examined possessed at least one genetic marker 87 .…”

Isolation and Identification of Potential Beer-Spoilage Pediococcus inopinatus and Beer-Spoilage Lactobacillus backi Strains Carrying the horA and horC Gene Clusters

“…Therefore, the potential applications of these genetic markers have been suggested to the comprehensive species-independent identification of beer-spoilage LAB strains. The horizontal transfer hypothesis of hop-resistance genes has been based on the sequence identities of the horA and horC-carrying DNA regions found in L. brevis, L. lindneri, L. paracollinoides and P. damnosus 17,[22][23][24] . Therefore we attempted to characterize the horA and horC-containing DNA regions in P. inopinatus and L. backi.…”