title: Genomic Characterization of Dairy AssociatedLeuconostocSpecies and Diversity of Leuconostocs in Undefined Mixed Mesophilic Starter Cultures.
abstract: Undefined mesophilic mixed (DL-type) starter cultures are composed of predominantlyLactococcus lactissubspecies and 1-10%Leuconostocspp. The composition of theLeuconostocpopulation in the starter culture ultimately affects the characteristics and the quality of the final product. The scientific basis for the taxonomy of dairy relevant leuconostocs can be traced back 50 years, and no documentation on the genomic diversity of leuconostocs in starter cultures exists. We present data on theLeuconostocpopulation in five DL-type starter cultures commonly used by the dairy industry. The analyses were performed using traditional cultivation methods, and further augmented by next-generation DNA sequencing methods. Bacterial counts for starter cultures cultivated on two different media, MRS and MPCA, revealed large differences in the relative abundance of leuconostocs. Most of the leuconostocs in two of the starter cultures were unable to grow on MRS, emphasizing the limitations of culture-based methods and the importance of careful media selection or use of culture independent methods. Pan-genomic analysis of 59Leuconostocgenomes enabled differentiation into twelve robust lineages. The genomic analyses show that the dairy-associated leuconostocs are highly adapted to their environment, characterized by the acquisition of genotype traits, such as the ability to metabolize citrate. In particular,Leuconostoc mesenteroidessubsp.cremorisdisplay telltale signs of a degenerative evolution, likely resulting from a long period of growth in milk in association with lactococci. Great differences in the metabolic potential betweenLeuconostocspecies and subspecies were revealed. Using targeted amplicon sequencing, the composition of theLeuconostocpopulation in the five commercial starter cultures was shown to be significantly different. Three of the cultures were dominated byLn. mesenteroidessubspeciescremoris. Leuconostoc pseudomesenteroidesdominated in two of the cultures whileLeuconostoc lactis, reported to be a major constituent in fermented dairy products, was only present in low amounts in one of the cultures. This is the first in-depth study ofLeuconostocgenomics and diversity in dairy starter cultures. The results and the techniques presented may be of great value for the dairy industry.
authors.affiliation: Laboratory of Microbial Gene Technology and Food Microbiology, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences Ås, Norway.
authors.forename: Cyril A
authors.initials: CA
authors.lastname: Frantzen
authors.affiliation: Department of Environmental Science, Aarhus University Roskilde, Denmark.
authors.forename: Witold
authors.initials: W
authors.lastname: Kot
authors.affiliation: Department of Food Science, University of Copenhagen Copenhagen, Denmark.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Pedersen
authors.affiliation: Department of Food Science, University of Copenhagen Copenhagen, Denmark.
authors.forename: Ylva M
authors.initials: YM
authors.lastname: Ardö
authors.affiliation: Department of Nutrition, Dietetics and Food Sciences, Utah State University Logan, UT, USA.
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Broadbent
authors.affiliation: Department of Microbiology and Biotechnology, Max Rubner-Institut Kiel, Germany.
authors.forename: Horst
authors.initials: H
authors.lastname: Neve
authors.affiliation: Department of Environmental Science, Aarhus University Roskilde, Denmark.
authors.forename: Lars H
authors.initials: LH
authors.lastname: Hansen
authors.affiliation: Sacco Srl Cordorago, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Dal Bello
authors.affiliation: Laboratory of Microbial Gene Technology and Food Microbiology, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences Ås, Norway.
authors.forename: Hilde M
authors.initials: HM
authors.lastname: Østlie
authors.affiliation: Laboratory of Microbial Gene Technology and Food Microbiology, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life SciencesÅs, Norway; ACD Pharmaceuticals ASLeknes, Norway.
authors.forename: Hans P
authors.initials: HP
authors.lastname: Kleppen
authors.affiliation: Department of Food Science, University of Copenhagen Copenhagen, Denmark.
authors.forename: Finn K
authors.initials: FK
authors.lastname: Vogensen
authors.affiliation: Laboratory of Microbial Gene Technology and Food Microbiology, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life SciencesÅs, Norway; TINE SAOslo, Norway.
authors.forename: Helge
authors.initials: H
authors.lastname: Holo
keywords: cheese; comparative; dairy; differentiation; diversity analysis; genomics; leuconostoc; starter cultures