AUTHOR=Wu Ruixue , Tao Ye , Cao Yina , Zhou Yan , Lin Huancai 

TITLE=Streptococcus mutans Membrane Vesicles Harboring Glucosyltransferases Augment Candida albicans Biofilm Development

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.581184

DOI=10.3389/fmicb.2020.581184

ISSN=1664-302X

ABSTRACT=<p><italic>Candida albicans</italic>, as the most common fungus in the oral cavity, is often detected in early childhood caries. <italic>Streptococcus mutans</italic> is the major etiological agent of dental caries, but the role of <italic>S. mutans</italic> on <italic>C. albicans</italic> growth and biofilm development remains to be elucidated. Membrane vesicles (MVs) are a cell-secreted subcellular fraction that play an important role in intercellular communication and disease progression. In the present study, we investigated whether MVs from <italic>S. mutans</italic> augment <italic>C. albicans</italic> growth and biofilm development. The results indicated that <italic>S. mutans</italic> MVs augmented <italic>C. albicans</italic> biofilm development but had no significant effect on <italic>C. albicans</italic> growth under planktonic conditions. Subsequently, we labeled <italic>S. mutans</italic> MVs with PKH26 and used confocal laser scanning microscopy (CLSM) to track <italic>S. mutans</italic> MVs, which were observed to be located in the <italic>C. albicans</italic> biofilm extracellular matrix. Monosaccharide tests showed that <italic>S. mutans</italic> MVs contribute to sucrose metabolism in <italic>C. albicans</italic>. Polysaccharides were significantly enriched in the <italic>S. mutans</italic> MV-treated group. MVs from Δ<italic>gtfBC</italic> mutant strains were compared with those from the wild-type <italic>S. mutans.</italic> The results revealed that MVs from the Δ<italic>gtfBC</italic> mutant had no effect on <italic>C. albicans</italic> biofilm formation and exopolysaccharide production. In addition, <italic>C. albicans</italic> biofilm transcriptional regulators (<italic>Ndt80</italic>, <italic>Als1</italic>, <italic>Mnn9</italic>, <italic>Van1</italic>, <italic>Pmr1</italic>, <italic>Gca1</italic>, and <italic>Big1</italic>) expression were upregulated in <italic>S. mutans</italic> MV-treated group. In summary, the results of the present study showed that <italic>S. mutans</italic> MVs harboring glucosyltransferases involved in exopolysaccharide production augment <italic>C. albicans</italic> biofilm development, revealing a key role for <italic>S. mutans</italic> MVs in cross-kingdom interactions between <italic>S. mutans</italic> and <italic>C. albicans</italic>.</p>