Veillonellaの硝酸還元作用に関する研究
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<I>Veillonella</I>, a strict anaerobe, which is one of the constituents of the habitual oral microflora, is known to have the strongest nitrate reduction ability of the oral microorganisms.<BR>The author isolated some <I>Veillonella</I> from human saliva and identified them as two species, <I>V</I>. <I>alcalescens</I> and <I>V</I>. <I>parvula</I>. Each <I>Veillonella</I> was inoculated and cultured in a medium containing nitrate. The concentration of nitrite produced by the action of nitrate reduction and the turbidity in the growth medium were measured. The processes of nitrate reduction was compared in the two <I>Veillonella</I> species in regard to the nitrite production, the bacterial growth, nitrate reduction ability, and nitrite reduction ability in the medium.<BR>The difference of nitrate reduction between <I>V</I>. <I>alcalescens</I> and <I>V</I>. <I>parvula</I> was not obvious in the logarithmic growth phase, but it was clearly demonstrated in the stationary phase, where the nitrite reduction was observed only in <I>V</I>. <I>alcalescens</I>. However, it was also found that <I>V</I>. <I>parvula</I> acquired nitrite reduction ability when it was cultured under aerobic conditions. This change in <I>V</I>. <I>parvula</I> seemed to be related to catalase action.<BR>Nitrate reductase activities of <I>Veillonella</I> were present mainly in the membrane-bound fraction at both the logarithmic and the stationary phases. But cytoplasmic nitrate reductase activities increased exceptionally at the stationary phase in <I>V</I>. <I>alcalescens</I>.<BR>From these results, it seemed that <I>V</I>. <I>parvula</I> showed the respiratory type of nitrate reduction, whereas <I>V</I>. <I>alcalescens</I> showed both the respiratory and the assimilative types; the respiratory type appeared at the logarithmic phase and the assimilative one mainly at the stationary phase.
- 有限責任中間法人 日本口腔衛生学会の論文