Unraveling the human salivary microbiome diversity in Indian populations

The importance of studying the salivary microbiome has been highlighted for its connection to health and disease and as a potential tool for supplementing human genetic diversity studies. While the salivary microbiome has been studied in various world populations, Indian populations have not been examined. We therefore analyzed microbiome diversity in saliva samples from 92 volunteers from eight different sampling locations in India by amplifying and sequencing variable regions (V1 and V2) of the bacterial 16S rRNA gene. The results showed immense bacterial richness in Indian populations; we identified 165 bacterial genera and 785 unique Operational Taxonomic Units (OTUs), with substantial sharing among the populations. There were small, but significant correlations in the abundance of bacterial genera in sampling locations from the same geographic region. Most of the core OTUs detected were also observed previously in other populations, but Solobacterium spp., Lachnoanaerobaculum spp. and Alloprevotella spp. were observed to be a component of the saliva microbiome unique to Indian populations. Importantly, nine bacterial genera were observed that were not listed in the Human Oral Microbiome Database (HOMD). These results highlight the importance of analyzing underrepresented populations like those of India.

唾液微生物组的研究价值已得到广泛重视，因其与人体健康和疾病密切相关，同时亦可作为补充人类遗传多样性研究的潜在工具。尽管全球多地人群的唾液微生物组已被广泛研究，但印度人群的相关研究仍属空白。为此，本研究通过扩增并测序细菌16S rRNA基因的可变区（V1、V2区），对来自印度8个不同采样点的92名志愿者的唾液样本中的微生物组多样性进行了分析。结果显示，印度人群的细菌丰富度极高：本研究共鉴定出165个细菌属与785个独特的操作分类单元（Operational Taxonomic Units，OTUs），且各人群间存在大量共有类群。同一地理区域内的不同采样点，其细菌属的丰度呈现微弱但显著的相关性。本研究检测到的多数核心OTUs在其他人群的样本中亦有报道，但Solobacterium属诸种、Lachnoanaerobaculum属诸种及Alloprevotella属诸种被证实为印度人群唾液微生物组所特有的类群。尤为重要的是，本研究发现了9个此前未被收录于人类口腔微生物组数据库（Human Oral Microbiome Database，HOMD）的细菌属。上述研究结果凸显了对印度这类代表性不足的人群开展微生物组研究的重要性。