Differentially regulated proteins in Prevotella intermedia after oxidative stress analyzed by 2D electrophoresis and mass spectrometry.

Prevotella intermedia is a rod-shaped, Gram-negative anaerobic bacterium found in human indigenous microbiota that plays an important role in opportunistic infections. The successful colonization depends on the ability of anaerobes to respond to oxidative stress (OS) in oxygenated tissues as well as to resist oxidative events from the host immune system until anaerobic conditions are present at the infection site. As knowledge of the mechanisms of protection against OS in Prevotella is limited, studies are needed to clarify aspects of molecular biology, physiology and ecology of this bacterium.

Actinomycetemcomitin: a new bacteriocin produced by Aggregatibacter (Actinobacillus) actinomycetemcomitans.

Aggregatibacter (Actinobacillus) actinomycetemcomitans P(7-20) strain isolated from a periodontally diseased patient has produced a bacteriocin (named as actinomycetemcomitin) that is active against Peptostreptococcus anaerobius ATCC 27337. Actinomycetemcomitin was produced during exponential and stationary growth phases, and its amount decreased until it disappeared during the decline growth phase. It was purified by ammonium sulphate precipitation (30-60% saturation), and further by FPLC (mono-Q ionic exchange and Phenyl Superose hydrophobic interaction) and HPLC (C-18 reversed-phase).

Enhanced pathogenicity of susceptible strains of the Bacteroides fragilis group subjected to low doses of metronidazole.

Different concentrations of metronidazole are used widely to treat protozoan and fungal infections. As an antibacterial drug, metronidazole is mainly used against anaerobes, of which the Bacteroides fragilis group is the most important in terms of the frequency of recovery and antimicrobial resistance patterns. The objective of this study was to investigate (1) in vivo metronidazole-induced modifications in the B.

Influence of abiotic factors on the bacteriocinogenic activity of Actinobacillus actinomycetemcomitans.

We evaluated the influence of abiotic factors on antagonistic activity of Actinobacillus actinomycetemcomitans strains isolated from periodontal pockets and two reference strains (ATCC 29523 and FDC Y4). Antagonistic assays were performed by the overlayer method on tryptic soy agar (TSA), brain heart infusion agar, thioglycollate agar and brucella agar, added with yeast extract and supplemented (S) or not with L-cystine and sodium bicarbonate. Iso-, auto-, and heteroantagonism against a wide range of indicator strains were assayed.