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Veillonella Role — MFDS Part 1 MCQ

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HardMicrobiologyVeillonella RoleMFDS Part 1

Metatranscriptomic analysis of supragingival plaque after repeated carbohydrate exposure shows increased Veillonella activity within microcolonies containing oral streptococci. Which metabolic activity most characteristically explains this ecological association?

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Correct answer: E — Use of lactate as a principal fermentable substrate under anaerobic conditions

Veillonella species are anaerobic, Gram-negative cocci with limited ability to ferment carbohydrates. They instead participate in metabolic cross-feeding by using lactate produced when neighbouring streptococci metabolise dietary carbohydrates. Lactate is converted into weaker organic acids, notably propionate and acetate, explaining the close ecological association between these organisms. This does not establish that Veillonella invariably prevents caries: Veillonella may also be abundant in cariogenic biofilms, so its overall effect depends on community ecology. Peptide fermentation with butyrate production is more characteristic of proteolytic periodontal organisms. Sucrose-dependent lactate and glucan production is associated with cariogenic streptococci. Urease-mediated ammonia production and ethanol oxidation are not the defining metabolic roles of Veillonella in plaque.

Reference: Wicaksono DP et al. Nitrite Production from Nitrate and Its Link with Lactate Metabolism in Oral Veillonella spp. Applied and Environmental Microbiology. 2020;86(20):e01255-20. https://pubmed.ncbi.nlm.nih.gov/32769185/