Abstract
The description of Gardnerella vaginalis was recently updated and three new species, including nine genome species within Gardnerella, were defined using whole genome sequences and matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry. A fast and simple method based on readily available techniques would be of immense use to identify Gardnerella species in research and clinical practice. Here we show that 34 previously characterized Gardnerella isolates were assigned to the species using partial chaperonin cpn60 sequences. The MALDI Biotyper from Bruker Daltonik GmbH demonstrated the capability to differentiate the phylogenetically diverse groups composed of G. vaginalis/G. piotii and G. leopoldii/G. swidsinskii. Among the phenotypic properties that characterize Gardnerella species are sialidase and β-galactosidase activities. Our data confirmed that the NanH3 enzyme is responsible for sialidase activity in Gardnerella spp. isolates. Almost all G. piotii isolates displayed a sialidase positive phenotype, whereas the majority of G. vaginalis strains were sialidase negative. G. leopoldii and G. swidskinskii displayed a sialidase negative phenotype. β-galactosidase is produced exclusively in G. vaginalis strains. Earlier determined phenotypic characteristics associated with virulence of Gardnerella isolates now assigned to the defined species may provide insights on how diverse species contribute to shaping the vaginal microbiome.
Highlights
Published: 1 March 2021Gardnerella vaginalis has been the only identified species in the genus Gardnerella for a long time
Earlier determined phenotypic characteristics associated with virulence of Gardnerella isolates assigned to the defined species may provide insights on how diverse species contribute to shaping the vaginal microbiome
While this bacterium is found to be closely associated with bacterial vaginosis (BV), a form of vaginal dysbiosis [1,2], Gardnerella isolates from BV-positive women showed genetic and phenotypic diversity [3,4,5]
Summary
Gardnerella vaginalis has been the only identified species in the genus Gardnerella for a long time. While this bacterium is found to be closely associated with bacterial vaginosis (BV), a form of vaginal dysbiosis [1,2], Gardnerella isolates from BV-positive women showed genetic and phenotypic diversity [3,4,5]. Gardnerella has been detected in vaginal microbial communities of healthy BV-negative women [1,6]. These findings suggest a diverse role of genetic variants of Gardnerella in the vaginal microbiota. The comparative genomic analysis of the 17 genomes allowed separating Gardnerella isolates into 4 subgroups, which likely are separate species [9,10]
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