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:Investigation of whole genome gene expression level changes in Lactococcus lactis KCTC 3769T,L. raffinolactis DSM 20443T, L. plantarum DSM 20686T, L. fujiensis JSM 16395T, L. garvieae KCTC 3772T, L. piscium DSM 6634T and L. chungangensis CAU 28T . This proves that transcriptional profiling can facilitate in elucidating the genetic distance between closely related strains.
