Evaluation of the Bacterial Diversity in the Human Tongue Coating Based on Genus-Specific Primers for 16S rRNA Sequencing

Abstract

The characteristics of tongue coating are very important symbols for disease diagnosis in traditional Chinese medicine (TCM) theory. As a habitat of oral microbiota, bacteria on the tongue dorsum have been proved to be the cause of many oral diseases. The high-throughput next-generation sequencing (NGS) platforms have been widely applied in the analysis of bacterial 16S rRNA gene. We developed a methodology based on genus-specific multiprimer amplification and ligation-based sequencing for microbiota analysis. In order to validate the efficiency of the approach, we thoroughly analyzed six tongue coating samples from lung cancer patients with different TCM types, and more than 600 genera of bacteria were detected by this platform. The results showed that ligation-based parallel sequencing combined with enzyme digestion and multiamplification could expand the effective length of sequencing reads and could be applied in the microbiota analysis.

Microbiota of the Tongue and Systemic Connections: The Examination of the Tongue as an Integrated Approach in Oral Medicine

“…The tongue inspection is a procedure that has been reported from the Shang Dynasty (from 1600 BC to 1000 BC) that should be performed by the clinical observation the tongue body to evaluate its morphological and color homogeneity. In accordance to the Traditional Chinese Medicine, the tongue is able to absolve a key role of a biosensor, while the different tongue regions are able to provide information to check the diagnosis the organ systems health [1,2].…”

“…The surface coating represents the exterior manifestation, which corresponds to the sustaining disease, and is the primary indication for the diagnosis making". In this way, the appropriate knowledge of the molecular aspects of tongue response is a key factor to comprehend this semeiotic medical practice [1,3,4]. Several studies on the microbiology of the healthy human tongue, through the sequencing of 16S rRNA, which is applied for the detection, categorization, and evaluation of the microbic charge within the biological mixtures, have shown that the most abundant phyla are Fusobacteria, Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes [1,4,5].…”

“…In this way, the appropriate knowledge of the molecular aspects of tongue response is a key factor to comprehend this semeiotic medical practice [1,3,4]. Several studies on the microbiology of the healthy human tongue, through the sequencing of 16S rRNA, which is applied for the detection, categorization, and evaluation of the microbic charge within the biological mixtures, have shown that the most abundant phyla are Fusobacteria, Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes [1,4,5]. The variation in the microbiota of the tongue lining recorded by metagenomic sequencing identifies potential biomarkers for several diseases, including the precancerous cascade [1,6,7].…”

“…The relationships between tongue diagnosis and diseases, including rheumatoid arthritis, gastritis and precancerous lesions, liver, pancreatic, and lung cancer, were explored [1,[10][11][12][13][14][15]. Tongue-lining microbiota biomarkers could provide a complement for the diagnosis of several diseases from the noninvasive, individualized, and long-term monitoring aspects [1,16]. Tongue diagnosis is a simple, noninvasive method of assessing physiological conditions by observing the thickness and color of the coating [6].…”

“…A yellow coat is considered an indication of water retention and heat [3]. The most common syndromes are the following four: external cold syndrome, internal cold syndrome, external heat syndrome, and internal heat syndrome, and are associated with thin white, thick white, thin yellow, and thick yellow tongue coatings [1]. Cold and hot syndromes are two contrary but internally related conditions [8].…”