Project description:Veillonella parvula is a biofilm-forming commensal found in the lungs, vagina, mouth, and gastro-intestinal tract of humans, yet it may also develop into an opportunistic pathogen. Furthermore the presence of Veillonella has been associated with the development of a healthy immune system in infants. Veillonella belongs to the Negativicutes, a diverse clade of bacteria that represent an evolutionary enigma: they are phylogenetically placed within Gram-positive (monoderm) Firmicutes yet maintain an outer membrane (OM) with lipopolysaccharide similar to classic Gram-negative (diderm) bacteria. The OMs of Negativicutes have unique characteristics, such as the replacement of Braun’s lipoprotein by OmpM for anchoring the outer membrane to the peptidoglycan. Through phylogenomic analysis, we have recently provided the first bioinformatic annotation of the Negativicute diderm cell envelope. We showed that it is a unique type of envelope that was present in the ancestor of present-day Firmicutes and lost multiple times independently in this phylum, giving rise to the monoderm architecture. However, little experimental data is presently available for any Negativicute cell envelope. Here, we have performed the first experimental proteomic characterization of the cell envelope of these atypical diderm Firmicutes, producing an OM proteome of Veillonella parvula. We initially conducted a thorough bioinformatics analysis of all 1844 predicted proteins from Veillonella parvula DSM 2008’s genome using seven different localization prediction programs. These results were then complemented by protein extraction with surface exposed protein tags and subcellular fractionation, which were then sequenced by liquid chromatography tandem mass spectrometry. The merging of proteomics and bioinformatics results allowed identification of 76 OM proteins. Their annotation markedly extends previous inferences on the nature of the cell envelope of Negativicutes, and provides important information on the role of OM systems in the lifestyle of Veillonella.
Project description:Streptococcus mutans was grown for 48 h in a biofilm in the absence (single species) and in the presence (dual species) of Veillonella parvula. In addition V. parvula single species 48 h biofilms were grown, to be used as a control. RNA was harvested from all types of biofilms and the transcript levels of the two types of biofilms containing S. mutans were compared with the use of S. mutans microarrays. V. parvula RNA was hybridized to S. mutans microarrays as a control for possible cross-hybridisation.
Project description:We investigated the specific interactions of the most dominant bacterial CF-pathogen, Pseudomonas aeruginosa, and the anaerobic bacterium Veilllonella parvula, that has been recovered at comparable cell numbers in the respiratory tract of CF patients. We used our recently established in-vivo murine tumor model to investigate mutual influences of the two pathogens during a biofilm-associated infection process. We found that although P. aeruginosa and V. parvula colonized distinct niches within the tumor, in mice that were co-infected with both bacterial species significant higher cell numbers of P. aeruginosa were recovered from the tumor tissue. Concordantly, in vivo transcriptional profiling implied that the presence of V. parvula supports P. aeruginosa growth at the infected host site, and the higher P. aeruginosa load correlated with clinical deterioration.
