18. Genome comparisons of Lactobacillus and Pediococcus reveal genetic markers of brewery adaptation

Barry Ziola (1), Jordyn Bergsveinson (1), Ilkka Kajala (2); (1) University of Saskatchewan, Saskatoon, SK, Canada; (2) VTT Technical Research Center of Finland Ltd., Espoo, Finland

Technical Session 5: Lactic Acid Bacteria
Sunday, August 14  •  2:00–3:15 p.m.
Plaza Building, Concourse Level, Governor’s Square 15

Comparative genomics is a powerful tool to determine genetic elements common to a group of isolates occupying a specific niche, such as a beer. For beer-spoiling–related lactic acid bacteria (BSR LAB), it is still unclear as to what taxonomic level comparisons are required to enable “beer-specific” genes to be elucidated. This is because LAB beer-spoilage ability is isolate-specific, with only selected members of different species and genera exhibiting spoilage ability. Furthermore, horizontal gene transfer is known to occur within the brewing environment where multiple LAB species may be present. Lastly, relatively few genomes of BSR LAB are publicly available to facilitate comparisons with non-BSR counterparts. Consequently, the extent to which genus-, species- or environment- (i.e., brewery-) related genetic variability influences beer-spoilage phenotype is unknown. Here we present four new genomes of BSR LAB isolates and perform intra-species comparison with all publicly available Lactobacillus brevis genomes, inter-species comparisons of BSR and non-BSR Lactobacillus genomes, and inter-genus comparisons of BSR and non-BSR Lactobacillus and Pediococcus genomes. These analyses revealed considerable differences between BSR LAB of different species and that the source location (brewery niche) of an isolate further influences the genetic profile of a BSR LAB. Of particular interest is the finding at the L. brevis-species level leads of genetics needed for carbohydrate nutrient scavenging of sorbose or other energy sources that yeast do not or cannot utilize, implying important adaptations to the brewery environment. In addition, enzymes related to the breakdown of plant materials appear to be characteristic of BSR L. brevis and potentially BSR lactobacilli writ-large. This finding strongly suggests that BSR L. brevis recovered from breweries, and potentially also other BSR LAB, have likely been sourced from plant niches. As well, these analyses provide evidence that much of the coding capacity of BSR LAB plasmids is specific to the brewery source. Together, the data support the theory that the beer-spoilage phenotype is a result of a “Swiss-army knife”-like approach, wherein multiple and variable genes are acquired by LAB, thus establishing beer-spoilage ability for particular bacterial isolates. Viewed in another way, the sum total of this genetic arsenal dictates LAB beer-spoilage spoilage virulence under different brewing or beer conditions. Further research into how genetic elements are transferred and harbored by microbes within the brewery environment and the total composition of BSR LAB microflora of breweries is critically important information for full interpretation of data derived from comparative genomics studies of BSR and non-BSR LAB.

Barry Ziola received a B.S. (Hons.) degree in botany from McGill University, Montreal, in 1970. After completing a Ph.D. degree in biochemistry at the University of Alberta, Edmonton, in 1975, he undertook a three-year postdoctoral stint at the University of Turku, Turku, Finland. He has been at the University of Saskatchewan, Saskatoon, since 1978, with promotion to professor in 1986. His interest and continuing research in brewing spoilage bacteria dates to the mid-1980s.