AUTHOR=Lu Yangyu , Lei Lei , Deng Yalan , Zhang Hongyu , Xia Mengying , Wei Xi , Yang Yingming , Hu Tao 

TITLE=RNase III coding genes modulate the cross-kingdom biofilm of Streptococcus mutans and Candida albicans

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.957879

DOI=10.3389/fmicb.2022.957879

ISSN=1664-302X

ABSTRACT=<p><italic>Streptococcus mutans</italic> constantly coexists with <italic>Candida albicans</italic> in plaque biofilms of early childhood caries (ECC). The progression of ECC can be influenced by the interactions between <italic>S. mutans</italic> and <italic>C. albicans</italic> through exopolysaccharides (EPS). Our previous studies have shown that <italic>rnc</italic>, the gene encoding ribonuclease III (RNase III), is implicated in the cariogenicity of <italic>S. mutans</italic> by regulating EPS metabolism. The <italic>DCR1</italic> gene in <italic>C. albicans</italic> encodes the sole functional RNase III and is capable of producing non-coding RNAs. However, whether <italic>rnc</italic> or <italic>DCR1</italic> can regulate the structure or cariogenic virulence of the cross-kingdom biofilm of <italic>S. mutans</italic> and <italic>C. albicans</italic> is not yet well understood. By using gene disruption or overexpression assays, this study aims to investigate the roles of <italic>rnc</italic> and <italic>DCR1</italic> in modulating the biological characteristics of dual-species biofilms of <italic>S. mutans</italic> and <italic>C. albicans</italic> and to reveal the molecular mechanism of regulation. The morphology, biomass, EPS content, and lactic acid production of the dual-species biofilm were assessed. Quantitative real-time polymerase chain reaction (qRT-PCR) and transcriptomic profiling were performed to unravel the alteration of <italic>C. albicans</italic> virulence. We found that both <italic>rnc</italic> and <italic>DCR1</italic> could regulate the biological traits of cross-kingdom biofilms. The <italic>rnc</italic> gene prominently contributed to the formation of dual-species biofilms by positively modulating the extracellular polysaccharide synthesis, leading to increased biomass, biofilm roughness, and acid production. Changes in the microecological system probably impacted the virulence as well as polysaccharide or pyruvate metabolism pathways of <italic>C. albicans</italic>, which facilitated the assembly of a cariogenic cross-kingdom biofilm and the generation of an augmented acidic milieu. These results may provide an avenue for exploring new targets for the effective prevention and treatment of ECC.</p>