Levan production by a strain of Rothia: activation of complement resulting in cytotoxicity for human gingival cells

Characterization of the Rothia spp. and their role in human clinical infections

The genus Rothia are emerging as opportunistic pathogens associated with various infections in immunocompromised and immunocompetent individuals. This review describes the taxonomy, cell wall structure, pathogenesis, phenotypic and molecular characteristics, clinical diseases, treatment and, as well as, the related genera that may be misidentified by Rothia species.

Purification and characterization of levanase from Actinomyces viscosus ATCC 19246

The extracellular levanase of Actinomyces viscosus ATCC 19246 was purified about 3,701-fold in 11% yield from the bacterial culture supernatant by means of ammonium sulfate precipitation, followed by DE52 column chromatography, Sephadex G-100 gel filtration, hydroxylapatite column chromatography, and Bio-Gel A 1.5m gel filtration. The molecular weight of the enzyme was estimated to be 89,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was optimally reactive at pH 6.0 and at 45 degrees C. The activity was inhibited by MnCl2, BaCl2, FeCl3, ZnCl2, HgCl2, and EDTA at a final concentration of 1 mM. The inhibition by EDTA was recovered by adding CaCl2 or MgCl2. The enzyme specifically hydrolyzed levan, but not sucrose, raffinose, melezitose, inulin, and dextran. These results indicate that the purified enzyme is specific for fructan (i.e., levan), which mainly consists of beta-(2,6) linkages.

Isolation and properties of levanase from Streptococcus salivarius KTA-19

Fructan-hydrolyzing enzyme from Streptococcus salivarius KTA-19 isolated from human dental plaque was investigated. The enzyme was purified by ammonium sulfate precipitation, acetone fractionation, and column chromatography on Bio-Gel and DEAE-cellulose. The purified enzyme showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing. Its molecular weight was 100,000 as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme exhibited an optimum pH of 6.5 and decreased its activity from pH 6.0 and especially below pH 5.5. The optimum temperature was 40 to 50 degrees C, and enzyme activity was reduced by 90% at 55 degrees C. Enzyme activity was markedly inhibited by Hg2+, Ag+, Cu2+, and p-chloromercuribenzoate at a concentration of 10(-3) M, but not by other metal ions or chemical effectors. Fructose was the only by-product of the enzyme action on levan. These results indicated that the levanase of S. salivarius KTA-19 is an exo-beta-(2,6)-fructofuranosidase.

Blastogenic response of human lymphocytes to antigens of Rothia dentocariosa

Peripheral blood lymphocytes were isolated from 20 individuals with varying degrees of periodontal health and classified as either normal, having acute gingivitis (GV), or chronic periodontitis (PD). Crude cell wall and cytoplasmic antigens were derived from Rothia dentocariosa (RD), were applied to lymphocyte microcultures, and subjected to radioactive thymidine; the resulting lymphocyte blastogenesis (LB) was surveyed with a scintillation counter. All three groups displayed statistically similar levels of stimulation (F = 0.71), demonstrating that crude antigens of RD are not appreciably active in vitro studies of cell-mediated immunity (CMI), as measured by LB.