R A Whiley — Page 3 | PubMed Health

PubMed1987

The relationship between glycosyltransferase production and membrane fatty acid composition of Streptococcus sanguis NCTC 7865 grown in the presence of protonmotive force inhibitors.

The fatty acid composition of Streptococcus sanguis NCTC 7865 was not altered by changing the cation composition (Na+/K+) of the growth medium; glucosyltransferase (GTF; EC 2.4.1.5) also remained constant. In contrast, fructosyltransferase (FTF-S; EC 2.4.1.10) production was reduced by at least 50% in medium with a high Na+ concentration. Growth in the presence of ionophores (gramicidin, nigericin or valinomycin) resulted in an increased proportion of saturated fatty acids, principally octadecanoic acid (C18:0), while the proportion of unsaturated fatty acids, predominantly octadecenoic (C18:1) and hexadecenoic (C16:1) acids, decreased. GTF-S production was reduced in the presence of ionophores whereas FTF-S production was completely abolished. Tween 80 significantly increased both GTF-S production and the proportion of unsaturated fatty acids in the cytoplasmic membrane; FTF-S production was unaltered by Tween 80. The production of GTF-S was inversely proportional to the C18:0:C18:1 fatty acid ratio of the cytoplasmic membrane. It was concluded that FTF-S production is directly influenced by protonmotive force (pmf), whereas GTF-S production is affected more by the physical properties of the cytoplasmic membrane, in particular its fatty acid composition. However, as perturbations in pmf generation can lead to variations in membrane fatty acid composition it can be argued that pmf indirectly influences GTF production by changing the saturated:unsaturated or C18:0:C18:1 fatty acid ratio of the cytoplasmic membrane.

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Antimicrobial effect of a novel ozone- generating device on micro-organisms associated with primary root carious lesions in vitro.

The aims of this present study were (1) to assess the antimicrobial effect of ozone from a novel ozone-generating device (Heolozone, USA) [0.052% (v/v) in air delivered at a rate of 13.33 ml.s(-1)] on primary root carious lesions (PRCLs) and (2) to evaluate the efficacy of ozone specifically on Streptococcus mutans and Streptococcus sobrinus. In study 1, 40 soft PRCLs from freshly extracted teeth were randomly divided into two groups to test the antimicrobial effect on PRCLs from exposure to ozonated water for either 10 or 20 s. Half of a lesion was removed using a sterile excavator. Subsequently, the remaining lesion was exposed to the ozonised water for a period of either 10 or 20 s (corresponding to 0. 069 or 0.138 ml of ozone, respectively). Using paired Student t tests, a significant (p<0.001) reduction (mean +/- SE) was observed in the ozone-treated groups with either a 10-second (log(10) 3.57+/-0.37) or 20-second (log(10) 3.77+/-0.42) ozone application compared with the control groups (log(10) 5.91+/-0.15 and log(10) 6.18+/-0.21, respectively). In study 2, 40 sterile saliva-coated glass beads were randomly divided into two groups for each micro-organism. One glass bead was put into each bijou bottle with 3 ml of Todd-Hewitt broth. S. mutans and S. sobrinus were inoculated anaerobically overnight. Each glass bead was then washed with 2 ml of phosphate-buffered saline. Immediately, 10 s of ozone gas was applied to each glass bead in the test groups. There was a significant (p<0.0001) reduction (mean +/- SE) in ozone-treated samples for S. mutans (log(10) 1.01+/-0.27) and S. sobrinus (log(10) 1.09+/-0.36) compared with the control samples (log(10) 3.93+/-0.07 and log(10) 4.61+/-0.13, respectively). This treatment regime is an effective, quick, conservative and simple method to kill micro-organisms in PRCLs. Ozone gas application for a period of 10 s was also capable of reducing the numbers of S. mutans and S. sobrinus on saliva-coated glass beads in vitro.

Anaerobiosis↗