*Article* **Salivary Microbiota Shifts under Sustained Consumption of Oolong Tea in Healthy Adults**

#### **Zhibin Liu, Hongwen Guo, Wen Zhang and Li Ni \***

Institute of Food Science & Technology, Fuzhou University, Fuzhou 350108, China; liuzhibin@fzu.edu.cn (Z.L.); guohongwen@fzu.edu.cn (H.G.); zhangwen@fzu.edu.cn (W.Z.)

**\*** Correspondence: nili@fzu.edu.cn; Tel.: +86-591-2286-6378

Received: 16 February 2020; Accepted: 25 March 2020; Published: 31 March 2020

**Abstract:** Tea is the most widely consumed beverages next to water, however little is known about the influence of sustained tea consumption on the oral bacteria of healthy adults. In this study, three oral healthy adults were recruited and instructed to consume 1.0 L of oolong tea infusions (total polyphenol content, 2.83 g/L) daily, for eight weeks. Salivary microbiota pre-, peri-, and post-treatment were fully compared by high-throughput 16S rRNA sequencing and multivariate statistical analysis. It was revealed that oolong tea consumption reduced salivary bacterial diversity and the population of some oral disease related bacteria, such as *Streptococcus* sp., *Prevotella nanceiensis*, *Fusobacterium periodonticum*, *Alloprevotella rava*, and *Prevotella elaninogenica*. Moreover, via correlation network and Venn diagram analyses, seven bacterial taxa, including *Streptococcus* sp. (OTU\_1), *Ruminococcaceae* sp. (OTU\_33), *Haemophilus* sp. (OTU\_696), *Veillonella* spp. (OTU\_133 and OTU\_23), *Actinomyces odontolyticus* (OTU\_42), and *Gemella haemolysans* (OTU\_6), were significantly altered after oolong tea consumption, and presented robust strong connections (|r| > 0.9 and *p* < 0.05) with other oral microbiota. These results sugges<sup>t</sup> sustained oolong tea consumption would modulate salivary microbiota and generate potential oral pathogen preventative benefits. Additionally, diverse responses to oolong tea consumption among subjects were also noticed.

**Keywords:** oolong tea; phenolic profile; salivary microbiota; 16S rRNA sequencing; bacterial diversities; correlation network
