bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/313965

Inhibitory Effect of Bacillus velezensis on Biofilm Formation by Streptococcus mutans

Yoo, Y.·Seo, D.-H.·Lee, H.·Nam, Y.-D.·Seo, M.-J.
View original source ↗Export metadata ↓

Abstract

Streptococcus mutans plays a key role in the development of dental caries and promotes the formation of oral biofilm produced by glucosyltransferases (GTFs). Bacillus velezensis K68 was isolated from traditional fermented foods and inhibits biofilm formation mediated by S. mutans. Gene amplification results demonstrated that B. velezensis K68 contained genes for the biosynthesis of 1-deoxynojirimycin (1-DNJ), a known GTF expression inhibitor. The presence of the GabT1, Yktc1, and GutB1 genes required for 1-DNJ synthesis in B. velezensis K68 was confirmed. Supernatant from B. velezensis K68 culture medium inhibited biofilm formation by 84% when S. mutans was cultured for 48 h, and inhibited it maximally when 1% glucose was added to the S. mutans culture medium as a GTF substrate. In addition, supernatant from B. velezensis K68 medium containing 3 ppb 1- DNJ decreased S. mutans cell surface hydrophobicity by 79.0 {+/-} 0.8% compared with that of untreated control. The supernatant containing 1-DNJ decreased S. mutans adherence by 99.97% and 98.83% under sugar-dependent and sugar-independent conditions, respectively. S. mutans treated with the supernatant exhibited significantly reduced expression of the essential GTF genes gtfB, gtfC, and gtfD compared to that in the untreated group. Thus, B. velezensis inhibits the biofilm formation, adhesion, and GTF gene expression of S. mutans through 1- DNJ production.\n\nIMPORTANCEDental caries is among the most common infectious diseases worldwide, and its development is closely associated with physiological factors of bacteria, such as the biofilm formation and glucosyltransferase production of Streptococcus mutans. Biofilms are difficult to remove once they have formed due to the exopolysaccharide matrix produced by the microorganisms residing in them; thus, inhibiting biofilm formation is a current focal point of research into prevention of dental caries. This study describes the inhibitory properties of Bacillus velezensis K68, an organism isolated from traditional Korean fermented foods, against biofilm formation by S. mutans. Herein, we show that B. velezensis inhibits the biofilm formation, adherence to surfaces, and glucosyltransferase production of S. mutans.

Source connections

Explore related subjects

microbiologyPreprint

Keep this discovery

BibTeXRIS

Yoo, Y., Seo, D.-H., Lee, H., Nam, Y.-D., Seo, M.-J.. 2018-05-04. Inhibitory Effect of Bacillus velezensis on Biofilm Formation by Streptococcus mutans. https://doi.org/10.1101/313965

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

A conserved cysteine-histidine-glutamate metal site identifies DUF501 (Rv1025), an essential uncharacterised protein family of Mycobacterium tuberculosis, as a candidate metalloenzyme and drug target

A substantial fraction of the Mycobacterium tuberculosis proteome remains functionally uncharacterised. Rv1025, a 155-residue protein carrying the domain of unknown function DUF501 (Pfam PF04417), is essential by transposon mutagenesis and vulnerable by CRISPR interference, an attractive but neglected drug target, yet has never been functionally described. The family (4,370 proteins, no Gene Ontology term, no solved structure) is uncharacterised across all organisms and essential in three Actinobacterial genera. A Foldseek search of the AlphaFold model against complete structural databases finds no significant homolog, indicating a novel fold. The operon eno-divIC-Rv1025-ppx2 is conserved across the Actinobacteria phylum, yet AlphaFold-Multimer finds no direct complex between Rv1025 and its neighbour DivIC. Instead, conservation across 8,700 homologous sequences reveals a near-invariant Cys113-His115-Glu59 cluster forming a pocket. Holo AlphaFold3 predictions with Zn, Fe and Mn confidently place a divalent metal on this triad at 2.25-2.47 A; mutating the triad relocates the metal, and an independent backbone-geometry predictor recovers the same site, confirming specificity. The triad is universal across the family: present in all 1,472 near-complete bacterial sequences of the Pfam alignment, with no non-conservative substitution among the 2,228 sequences examined, a defining feature of bacterial DUF501 rather than a mycobacterial peculiarity. We propose that DUF501 is a metal-binding protein and candidate metalloenzyme, the first functional hypothesis for this family, whose conserved, essential metal pocket is a promising drug target. As the predictions build on a conservation-defined site within a fully computational study, they are supportive rather than proof of metal occupancy and warrant experimental validation.

microbiology↗
bioRxiv2026

Mycoplasmal endosymbionts of Trichomonas vaginalis are associated with reduced risk for Chlamydia trachomatis endometrial infection in asymptomatic, coinfected, women.

Trichomonas vaginalis is a protozoan parasite that causes trichomoniasis, the most common curable non-viral sexually transmitted infection, and Chlamydia trachomatis is a bacterial pathogen that can ascend to the upper genital tract and cause pelvic inflammatory disease, infertility, and ectopic pregnancy. T. vaginalis harbors bacterial endosymbionts, including Candidatus Malacoplasma girerdii, an obligate symbiont, and Metamycoplasma hominis, which can live freely or symbiotically. In a 16S rRNA sequencing study of the cervicovaginal microbiome of women at high risk for chlamydial infection, Ca. M. girerdii abundance was one of 13 features predicting lack of chlamydial spread to the endometrium, despite no direct association between T. vaginalis infection and reduced chlamydial ascension. Investigating the relationship between these microorganisms further, we found that T. vaginalis vaginal abundance correlated positively with chlamydial burden in women whose infection was confined to the cervix, while a nonsignificant inverse relationship was seen in women with endometrial spread. Among participants with high chlamydial burden, Ca. M. girerdii was detected exclusively in women without endometrial infection. Both endosymbionts trended toward more frequent detection, and higher abundance, in coinfected women without endometrial spread, while M. hominis abundance correlated strongly with T. vaginalis burden in this group. These findings suggest that mycoplasmal endosymbionts of T. vaginalis, rather than T. vaginalis itself, are microbial factors limiting chlamydial ascension, and point to a three-way interaction between parasite, endosymbiont, and bacterial pathogen that shapes upper genital tract C. trachomatis infection risk.

microbiology↗
bioRxiv2026

Understanding the physiological alterations of Vibrio cholerae upon exposure to L-ascorbic acid

The scourge of cholera remains a major global public health threat. It affects up to 4 million people worldwide and causes tens of thousands of deaths each year. The disease is experiencing a concerning resurgence in many parts of Africa, the Middle East, and Asia. To effectively tackle cholera and circumvent rising antimicrobial resistance, targeted biological and preventive approaches, complementing traditional rehydration, are urgently needed. In this regard, our group has demonstrated the efficacy of L-ascorbic acid in controlling the growth and pathogenesis of Vibrio cholerae in vitro. The present work further provides a mechanistic elucidation of the L-ascorbic acid-mediated physiological changes in V. cholerae and also bolsters such a non-antibiotic approach to control cholera.

microbiology↗