Project description:BackgroundDental caries is a chronic oral disease caused by microbial infections, which result in erosion of the dental enamel and cause irreversible damage. Therefore, proper disease management techniques and the creation of an environment that prevents intraoral growth and biofilm formation of Streptococcus mutans in the early stages, are crucial to prevent the potential progression of dental plaque to disease. Here, we aimed to investigate antimicrobial and antibiofilm effects of the Bacillus velezensis ID-A01 supernatant (ID23029) against S. mutans, and its inhibitory effects on acidogenesis.ResultsA killing kinetics assay showed a peak lethality percentage of 94.5% after 6 h of exposure to ID23029. In sucrose-exposed conditions, ID23029 inhibited lactic acid formation, preventing the pH from falling below the threshold for enamel demineralization, and inhibited up to 96.6% of biofilm formation. This effect was maintained in the presence of lysozyme. Furthermore, ID23029 retained up to 92% lethality, even at an intraoral concentration at which lysozyme is ineffective against S. mutans.ConclusionsThis study demonstrates the potential of the B. velezensis ID-A01 supernatant for the prevention and treatment of dental caries. Its eventual use in dental practice is encouraged, although further studies are required to confirm its beneficial effects.
Project description:Bacillus velezensis strain GH1-13 isolated from a rice paddy soil in Korea has been reported to promote plant growth and inhibit some pathogens. It contains a plasmid pBV71, thought to be of benefit to the strain, but there is no information on its effect. In order to elicit the plasmid effect on gene expression, mRNA and protein levels were analyzed at various stages of bacterial growth. Comparative gene expression profiles between the plasmid-containing and plasmid-free cells revealed that strain GH1-13 activated a transient stress response in the exponential phase. It showed early activation of expression of sigma W operon, liaIHGFSR operon, and transcription regulators for transition state, associated with carbon catabolite repression and secondary metabolite biosynthesis of acetoin, bacillaene, and macrolactin.
Project description:Bacillus velezensis strain GH1-13 with a native conjugative plasmid (pBV71) is thought to be beneficial to the bacterium, although no information on its effects exists. Here we show that strain GH1-13 frequently lost the plasmid during normal growth conditions in a rich medium and changed the morphology and sensitivity to selenite and tellurite. Compared to the plasmid-cured cells, the wild-type and complemented cells exhibited multicellular behavior with the expression of conjugative type IV pili and regulatory Rap homologous genes that regulate the interconnection between conjugation and biofilm formation. Further omics-based analyses of morphogenesis, biofilm formation, and antibiotic synthesis suggest that the conjugative plasmid activates envelope stress responses in association with increased biosynthesis of extracellular polysaccharide and antibiotics for protective functions of the host during exponential phase.