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At least 973 records · Page 54Linked to original sources
PubMed1982

Minimum nutritional requirements for cellular growth and extracellular slime polysaccharide production by the human dental plaque bacterial mutant Actinomyces viscosus T14Av.

The requirements were examined in chemically-defined media. Magnesium sulphate, potassium phosphate and adenine were essential for cellular growth and sodium bicarbonate and inositol further stimulated growth. The addition of sodium phosphate to this medium stimulated both cellular growth and slime production. In contrast, ammonium sulphate inhibited slime production. Biotin and thiamine stimulated cellular growth and nicotinic acid was essential for slime production. Glutamine, alanine and cystine were essential for cellular growth. A minimal medium which supported both good cellular growth and slime production for strain T14Av contained adenine, sodium bicarbonate, MgSO4, inositol, glucose, KH2PO4, Na2HPO4, biotin, thiamine, nicotinic acid, arginine, glutamine, alanine and cystine.

Actinomyces↗
PubMed1982

Morphological, chemical and antigenic characterization of M-1 N-acetylmuramidase-digested cell walls of the oral pathogenic bacterium Actinomyces viscosus T14V and T14AV.

The cell walls were enzymically solubilized with M-1 N-acetylmuramidase. The minimum amount of enzyme required for maximum response was 70 micrograms/mg of wall. The action of the enzyme seemed localized, producing holes in the wall structure. Chemistry and morphology suggested that all of the wall was solubilized. Antigenically, anti-T14AV formed precipitates with 11-14 antigens from the solubilized walls, of which 3 are unique to strain T14AV. Many of these antigens have not been observed previously due to the physical and/or chemical degradation associated with the extraction procedures. Antisera prepared against strain T14V whole cells formed precipitates with only a few antigens common to both strains. The results suggest that immunological processing and/or surface localization of these antigens are different.

Actinomyces↗
PubMed1983

Colonization of the teeth of rats by human and rodent oral strains of the bacterium Actinomyces viscosus.

The mouths of rats were infected with human and rodent strains of A. viscosus and streptomycin-rifamycin-resistant (SR) mutants of these strains. The establishment, adherence to the teeth and cell dose required for infection were determined. Human and rodent strains established equally well on the teeth and did not differ in their initial adherence to teeth. The cell dose required for infection was much lower for rodent than for human strains (less than 10(5) compared to 10(7) - 10(8) c.f.u.). The SR mutants established as well as their parents except for one SR strain, that did not establish at all. Another SR mutant appeared to have lost its SR resistance after passage through the animal. The results stress the need of in-vivo testing of antibiotic resistant mutants to be used in ecological studies.

Actinomyces↗
PubMed1984

The effects of mutual interaction and host diet on the growth rates of the bacteria Actinomyces viscosus and Streptococcus mutans during colonization of tooth surfaces in di-associated gnotobiotic rats.

The bacteria were simultaneously inoculated into the mouths of germ-free rats. The maximum growth rates attained by Strep. mutans (doubling time td = 1.4 h) or A. viscosus (td = 2.7 h) were approximately the same as in mono-associated gnotobiotic rats [td = 1.1 and 2.8 h, respectively (Beckers and van der Hoeven, 1982a)]. The presence of glucose or sucrose did not affect the maximum growth rates. In starved rats, the accumulation of microorganisms tended to decline sooner, suggesting that the growth was limited by the availability of nutrients. No interaction between the two organisms was detected at the stage of initial adherence to the tooth surfaces or during the first 24 h of growth. After that, the increase of A. viscosus was retarded in the presence of Strep. mutans T2, but not with Strep. mutans OMZ176. The retardation was more pronounced in the rats fed on glucose than on sucrose. Yet, at 24 days after inoculation. A. viscosus had increased in the glucose more than in the sucrose group. Hence sucrose did not stimulate the accumulation of Strep. mutans more than glucose.

Actinomyces↗
PubMed1984

The pattern of experimental colonization of a human and a rodent strain of the bacterium Actinomyces viscosus on the dentition of the rat.

Samples were taken from mesial, buccal, lingual and approximal sites and from fissures. Initially, most A. viscosus were recovered from the retention sites. With the exception of lingual sites during the period of exponential growth, the apparent doubling times calculated for A. viscosus Nyl SR remained within narrow limits for all locations. After cessation of exponentional growth, both strains had colonized all surfaces. However, the rodent strain A. viscosus Nyl SR had formed 30-800 times larger populations on the smooth surfaces than the human strain A. viscosus Ut2 . On the retention sites, the populations of both strains were not significantly different.

Actinomyces↗
PubMed1985

The mitogenicity for murine splenocytes of specific surface components of the oral periodontopathic bacterium, Actinomyces viscosus.

Many characterized fractions obtained from A. viscosus were examined to identify the macromolecules responsible for mitogenicity for lymphocytes. Spleen-cell suspensions of CBA/J mice were cultured with 50-200 micrograms dry weight of A. viscosus strains T14V and T14AV cellular components. Lipopolysaccharide (LPS) (Escherichia coli) was used as a positive control. Mechanical disruption with a French pressure cell or sonication produced preparations with a stimulation of 69,082 and 45,183 counts above background (CAB), respectively. Mitogenic activity was also present in the culture supernatant (38,000 CAB). Other poorly mitogenic fractions included the peptidoglycan, cell-wall fractions, muramidase digests of cell walls, and the microcapsule extracted from whole cells with 0.5 M MgNO3. The results suggest that mitogenic activity is not associated with the isolated cell-wall structure. The activity was released from the cell surface by physical shearing forces, as well as released into the medium growth.

Actinomyces↗