Authors
Young-Seon Kim, Hyunsook Kim, Wallace H Yokoyama, Nitin Nitin, Kun-Ho Seo
Published in
Journal of microbiology and biotechnology. Volume 36. Pages e2607002. Sep 21, 2026. Epub Sep 21, 2026.
Abstract
Postbiotic metabolites from lactic acid bacteria (LAB) offer antimicrobial functionality without the safety and stability constraints of live probiotics. Here, we evaluated cell-free supernatants from kefir-derived LAB against the periodontal pathogen Campylobacter rectus and characterized their inhibitory components. Four kefir isolates (Lactobacillus kefiranofaciens DD2 and DN1, Lentilactobacillus kefiri DH5, and Leuconostoc mesenteroides DH1608) suppressed C. rectus growth, with maximal inhibition after 72 h culture at 30°C. The antimicrobial activity was largely retained under acidic conditions, but reduced after heat treatment in DD2 and DH5, indicating heat-labile inhibitory component(s) in addition to organic acids. Enzymatic treatment revealed a proteinaceous component in DD2 metabolites, as proteases (proteinase K and trypsin) significantly reduced inhibitory activity. High-performance liquid chromatography (HPLC) quantification confirmed high lactic acid levels (285.77-359.83 mM) and elevated propionic acid (26-28 mM) in all supernatants. Lactic acid (300 mM) and propionic acid (25 mM) individually inhibited C. rectus growth. A protein-/polypeptide-enriched fraction from L. kefiranofaciens DD2 (highest yield: 12.58 ± 0.77 mg/L) showed antimicrobial activity (48.16 ± 13.27%), and tricine-SDS-PAGE revealed an approximately 28-kDa band within this fraction. However, the active component(s) were not molecularly identified, and further activity-guided purification and LC-MS/MS analysis are required. Collectively, kefir-derived LAB postbiotics inhibit C. rectus growth through combined organic acid and proteinaceous mechanisms, supporting their development as postbiotic candidates for oral health applications targeting this periodontal pathogen.
PMID:
42927991
Bibliographic data and abstract were imported from PubMed on 26 Oct 2026.
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