Lactate influx and efflux in the 'Streptococcus mutants group' and Streptococcus sanguis.

Lactate influx was measured in Streptococcus sanguis and in several strains of Streptococcus mutans by comparing the intra- and extracellular distribution of (14C)-lactate. Lactate efflux was followed enzymatically against rising external lactate concentration. The glucose concentration was monitored in the same way. With S. sanguis OMZ 9, lactate was transported into the cells when a high external lactate concentration and a pH gradient were established. The transport rate was approximately 1,000 nmol lactate per minute and milligram protein. No lactate influx could be measured with four strains of the 'S. mutans group' (OMZ 51, 634, T3/13 and NCTC 10449). Metabolizing cells of S. mutans NCTC 10449 were able to transport lactate even against an external lactate concentration of 92 mmol/l at pH = 7. The transport rates ranged from 1,200 to 750 nmol lactate/min mg protein decreasing with increasing external lactate concentration. While an external pH = 9 had little influence on transport, transport rates decreased to 440 nmol/min mg protein at pH = 5.

Characterization of lectinlike surface components on Capnocytophaga ochracea ATCC 33596 that mediate coaggregation with gram-positive oral bacteria.

The interactions between Capnocytophaga ochracea ATCC 33596 and Streptococcus sanguis H1, Actinomyces naeslundii PK984, or Actinomyces israelii PK16 are dependent on specific recognitions between heat-sensitive adhesins on C. ochracea and heat-stable structures (probably carbohydrate-containing receptors) on the surfaces of these gram-positive coaggregation partners. The coaggregation of C. ochracea with each of these three organisms was inhibited by L-rhamnose and D-fucose and to a lesser extent by beta-methyl-galactoside. The reaction with S. sanguis was the most sensitive, while the coaggregation with A. israelii was the least sensitive and was only partially inhibited by each of the sugars that were considered to be effective inhibitors. A more effective inhibition of the coaggregation between C. ochracea and A. israelii was achieved by adding a combination of the 6-deoxysugars and N-acetylneuraminic acid. To further characterize the coaggregations, naturally occurring coaggregation-defective (Cog-) mutants of C. ochracea were obtained from several different selections. Three phenotypically distinct groups of mutants were were isolated. Type 1 mutants failed to coaggregate with S. sanguis only. Type 2 mutants lost ability to interact with both S. sanguis and A. naeslundii. Type 3 mutants failed to coaggregate with all three coaggregation partners. Characterization of the Cog- mutants by sugar inhibition studies made it possible to distinguish three classes of adhesin activity.

Identification and preliminary characterization of a lectinlike protein from Capnocytophaga gingivalis (emended).

A polypeptide believed to be the monomeric form of the lectin responsible for the coaggregation of Capnocytophaga gingivalis (emended) and Actinomyces israelii has been identified. Denaturing polyacrylamide gel electrophoresis and immunoblot analyses were used to distinguish the protein from other proteins in the outer membrane of C. gingivalis. The subunit of the putative lectin has a pI of 8.6 and a molecular weight of 155,000.

Actinobacillus actinomycetemcomitans strains Y4 and N27 adhere to hydroxyapatite by distinctive mechanisms.

Actinobacillus actinomycetemcomitans strains Y4 and N27 absorb to spheroidal hydroxyapatite in roughly the same numbers per milligram of substrate and with the same tenacity as two previously tested Cytophaga species. Although the two strains of A. actinomycetemcomitans exhibited similar affinities and number of binding sites for SHA, their response to enzyme treatment and heating were very different. The capacity of strain Y4 to attach to spheroidal hydroxyapatite was diminished by treatment with proteases and phospholipases and was unaffected by neuraminidase, while strain N27 was unaffected by proteases and phospholipases and lost its binding capabilities when treated with neuraminidase.

Evidence for the participation of N-acetylated amino sugars in the coaggregation between Cytophaga species strain DR2001 and Actinomyces israelii PK16.

Coaggregation between Cytophaga sp. strain DR2001 and Actinomyces israelii PK16 was partially inhibited by certain N-acetylated amino sugars (N-acetylneuraminic acid, N-acetylgalactosamine, and N-acetylglucosamine) and was completely inhibited by the trisaccharide neuraminin-lactose. The monosaccharides exerted their effect at concentrations between 30 to 100 mM, whereas the trisaccharide was an effective inhibitor at significantly lower concentrations. Outer membrane preparations caused A. israelii PK16 cells to aggregate; however, vesicles released from the cell envelope during growth failed to do so. Adherence studies with a non-coaggregating mutant of the cytophaga suggest that the spheroidal hydroxyapatite attachment sites and coaggregation receptors are separate entities.