title: Shotgun mass mapping of Lactobacillus species and subspecies from caries related isolates by MALDI-MS.
abstract: A taxonomical study of 90 isolates of lactobacilli isolated from soft and hard carious dentine of 70 deciduous molars is presented. The Lactobacillus strains were determined by shotgun mass mapping (SMM). This method based on MALDI-MS analysis of Lactobacillus isolates treated with trypsin followed by database comparison against a library of mass spectra derived from 20 reference strains. The SMM method allowed to discriminate different Lactobacillus subspecies. The method was used to analyse Lactobacillus isolates of unknown identity derived from carious dentine. Application of the SMM method to isolates from hard carious dentine revealed a nearly similar distribution of L. paracasei ss paracasei (29%), L. paracasei ss tolerans (32%) and L. casei ss rhamnosus (23%) as dominant subspecies. On the other hand, samples derived from soft carious dentine showed a clear bias only to L. paracasei ss paracasei (60%), whereas L. paracasei ss tolerans (14%) and L. casei ss rhamnosus (12%) were clear minorities. Compared to existent methods, SMM has unique potential for the analysis of Lactobacillus strains on subspecies level.
authors.affiliation: The Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway.
authors.forename: Frank
authors.initials: F
authors.lastname: Schmidt
authors.forename: Thomas
authors.initials: T
authors.lastname: Fiege
authors.forename: Hanne K
authors.initials: HK
authors.lastname: Hustoft
authors.forename: Susanne
authors.initials: S
authors.lastname: Kneist
authors.forename: Bernd
authors.initials: B
authors.lastname: Thiede
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002648:Child; D016000:Cluster Analysis; D030562:Databases, Protein; D003731:Dental Caries / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology; D006801:Humans; D007778:Lactobacillus / Q000145:classification* / Q000378:metabolism; D008963:Molar / Q000382:microbiology; D010446:Peptide Fragments / Q000378:metabolism; D010449:Peptide Mapping; D010802:Phylogeny; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014094:Tooth, Deciduous / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D010446:Peptide Fragments