AUTHOR=Liu Shanshan , Sun Yu , Liu Yudong , Hu Fuyong , Xu Li , Zheng Qingwei , Wang Qinglong , Zeng Guojin , Zhang Kai 

TITLE=Genomic and phenotypic characterization of Streptococcus mutans isolates suggests key gene clusters in regulating its interaction with Streptococcus gordonii

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.945108

DOI=10.3389/fmicb.2022.945108

ISSN=1664-302X

ABSTRACT=<p><italic>Streptococcus mutans</italic> (<italic>S. mutans</italic>) is one of the primary pathogens responsible for dental caries. <italic>Streptococcus gordonii</italic> (<italic>S. gordonii</italic>) is one of the early colonizers of dental plaque and can compete with <italic>S. mutans</italic> for growth. In the present analysis, we explored key target genes against <italic>S. gordonii</italic> in <italic>S. mutans</italic> using 80 <italic>S. mutans</italic> clinical isolates with varying capabilities against <italic>S. gordonii</italic>. A principal coordinate analysis revealed significant genetic diversity differences between antagonistic and non-antagonistic groups. Genomic comparisons revealed 33 and 61 genes that were, respectively, positively and negatively correlated with <italic>S. mutans</italic> against <italic>S. gordonii</italic>, with RNA-sequencing (RNA-seq) highlighting 11 and 43 genes that were, respectively, upregulated and downregulated in the antagonistic group. Through a combination of these results and antiSMASH analysis, we selected 16 genes for qRT-PCR validation in which the expression levels of SMU_137 (malate dehydrogenase, mleS), SMU_138 (malate permease, mleP), SMU_139 (oxalate decarboxylase, oxdC), and SMU_140 (glutathione reductase) were consistent with RNA-seq results. SMU_1315c-1317c (SMU_1315c transport-related gene) and SMU_1908c-1909c were, respectively, downregulated and upregulated in the antagonistic group. The expression patterns of adjacent genes were closely related, with correlation coefficient values greater than 0.9. These data reveal new targets (SMU_137–140, SMU_1315c-1317c, and SMU_1908c-1909c) for investigating the critical gene clusters against <italic>S. gordonii</italic> in <italic>S. mutans</italic> clinical isolates.</p>