Disruption of a Novel Iron Transport System Reverses Oxidative Stress Phenotypes of a Mutant Strain of Streptococcus mutans.

The Dps-like peroxide resistance protein (Dpr) is essential for HO stress tolerance and aerobic growth of the oral pathogen Dpr accumulates during oxidative stress, protecting the cell by sequestering iron ions and thereby preventing the generation of toxic hydroxyl radicals that result from the interaction of iron with HO Previously, we reported that the SpxA1 and SpxA2 regulators positively regulate expression of in Using an antibody raised against Dpr, we confirmed at the protein level the central and cooperative nature of SpxA1 and SpxA2 regulation in Dpr production. During phenotypic characterization of the Δ strain, we observed the appearance of distinct colony variants, which sometimes lost the oxidative stress sensitivity typical of Δ strains. Whole-genome sequencing of these phenotypically distinct Δ isolates revealed that a putative iron transporter operon, , was a genomic hot spot with multiple single nucleotide polymorphisms identified within the different isolates.

Transcriptional and Phenotypic Characterization of Novel Spx-Regulated Genes in Streptococcus mutans.

In oral biofilms, two of the major environmental challenges encountered by the dental pathogen Streptococcus mutans are acid and oxidative stresses. Previously, we showed that the S. mutans transcriptional regulators SpxA1 and SpxA2 (formerly SpxA and SpxB, respectively) are involved in stress survival by activating the expression of classic oxidative stress genes such as dpr, nox, sodA and tpx.

Action of essential oils from Brazilian native and exotic medicinal species on oral biofilms.

Background: Essential oils (EO) obtained from twenty medicinal and aromatic plants were evaluated for their antimicrobial activity against the oral pathogens Candida albicans, Fusobacterium nucleatum, Porphyromonas gingivalis, Streptococcus sanguis and Streptococcus mitis.

Methods: The antimicrobial activity of the EO was evaluates by microdilution method determining Minimal Inhibitory Concentration. Chemical analysis of the oils compounds was performed by Gas chromatography-mass spectrometry (CG-MS).