The influence of biosurfactants released by S-mitis BMS on the adhesion of pioneer strains and cariogenic bacteria

The influence of Streptococcus mitis BMS biosurfactants on the adhesion of eight pioneer and four cariogenic oral bacterial strains was, for a first screening, examined in a microtiter plate assay. The adhesion to pellicle-coated wells of three cariogenic strains was inhibited >70% by the biosurfactants, while only one pioneer strain showed >70% reduction. The reduction for the other strains did not exceed 50%. Subsequently, adhesion of Streptococcus mutans ATCC 25175 and Streptococcus sobrinus HG 1025, both cariogenic strains, and Actinomyces naeslundii T14V-J1 and Streptococcus oralis J22, two pioneer strains, to biosurfactants-coated enamel with and without a salivary pellicle was studied in a parallel plate flow chamber. A biosurfactants coating to enamel with or without a pellicle caused a reduction in the number of adhering cariogenic organisms, although no such reduction was observed for the pioneer strains. Consequently, it is concluded that S. mitis BMS biosurfactants may play a protective role against adhesion of cariogenic bacteria

Fourier transform infrared spectroscopy studies of alginate-PLL capsules with varying compositions

Microencapsulation of cells is a promising approach to prevention of rejection in the absence of immunosuppression. Clinical application, however, is hampered by insufficient insight into the factors that influence the biocompatibility of the capsules. Capsules prepared of alginates with a high guluronic (G) acid content proved to be more adequate for clinical application since they are more stable, but, unfortunately, they are less biocompatible than capsules prepared of intermediate-G alginate. In order to get some insight into the physicochemical factors that influence the biocompatibility of capsules for the encapsulation of living cells, the chemical compositions of alginate-Ca beads and alginate-PLL capsules were studied by Fourier transform infrared spectroscopy. We found that during the transition of the alginate-Ca beads to alginate-PLL capsules, Ca connecting the alginate molecules, disappeared at the surface of both high-G and intermediate-G alginate-PLL capsules. At the same time, it turned out that high-G alginate-PLL capsules contained more hydrogen bonding than did intermediate-G alginate capsules. Thus the well-known higher stability of high-G alginate-PLL compared to intermediate-G alginate-PLL capsules is not caused by a higher degree of binding to Ca of the alginate molecules but rather by the presence of more hydrogen bonds. Another observation was that after the transition from bead to capsule, high-G alginate-PLL capsules contained 20% more PLL than the intermediate-G alginate-PLL capsules. Finally, we show that in both high-G and intermediate-G alginate-PLL capsules, the PLL exists in the a-helix, in the antiparallel beta-sheet, and in the random coil conformation. This study shows that FT-IR allows for successful analyses of the chemical factors essential for understanding differences in the biocompatibility of alginate-PLL capsules. (C) 2003 Wiley Periodicals, Inc

Influence of biosurfactant on interactive forces between mutans streptococci and enamel measured by atomic force microscopy

Although interactive forces, influenced by environmental conditions, between oral bacteria and tooth surfaces are important for the development of plaque, they have never been estimated. It is hypothesized that interactive forces, as measured by atomic force microscopy, between enamel with or without a pellicle and two strains of mutans streptococci become less attractive by the application of a Streptococcus mitis BMS biosurfactant coating. Upon approach of each of the strains toward bare and pellicle-coated enamel, adsorbed biosurfactant increased the range of the repulsive forces. Upon retraction of the enamel surface, small adhesion forces (0.8-0.9 nN) were measured for bare enamel that almost disappeared after biosurfactant coating. The prevalence and magnitude of the adhesion forces also decreased upon pellicle-coating of the enamel, with a minor effect of adsorbed biosurfactant. These findings indicate that adsorbed S. mitis BMS biosurfactant changes the interactive forces between the mutans streptococci studied and enamel, explaining the effects of biosurfactant on adhesion

Reduction of periodontal pathogens adhesion by antagonistic strains

Introduction: Periodontitis results from a shift in the subgingival micro. ora into a more pathogenic direction with Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans considered as periodontopathogens. In many cases, treatment procures only a temporary shift towards a less pathogenic microflora. An alternative treatment could be the deliberate colonization of pockets with antagonistic microorganisms to control the adhesion of periodontopathogens. The aim of this study was to identify bacterial strains that reduce adhesion of periodontopathogens to surfaces.status: publishe

Role of calcium alginate and mannitol in protecting Bifidobacterium

Fourier transform infrared (FTIR) spectroscopy was carried out to ascertain the mechanism of Ca-alginate and mannitol protection of cell envelope components and secondary proteins of Bifidobacterium animalis subsp. lactis Bb12 after freeze-drying and after 10 weeks of storage at room temperature (25°C) at low water activities (aw) of 0.07, 0.1, and 0.2. Preparation of Ca-alginate and Ca-alginate-mannitol as microencapsulants was carried out by dropping an alginate or alginate-mannitol emulsion containing bacteria using a burette into CaCl2 solution to obtain Ca-alginate beads and Ca-alginate-mannitol beads, respectively. The wet beads were then freeze-dried. The aw of freeze-dried beads was then adjusted to 0.07, 0.1, and 0.2 using saturated salt solutions; controls were prepared by keeping Ca-alginate and Ca-alginate-mannitol in aluminum foil without aw adjustment. Mannitol in the Ca-alginate system interacted with cell envelopes during freeze-drying and during storage at low aws. In contrast, Ca-alginate protected cell envelopes after freeze-drying but not during 10-week storage. Unlike Ca-alginate, Ca-alginate-mannitol was effective in retarding the changes in secondary proteins during freeze-drying and during 10 weeks of storage at low aws. It appears that Ca-alginate-mannitol is more effective than Ca-alginate in preserving cell envelopes and proteins after freeze-drying and after 10 weeks of storage at room temperature (25°C)