Characterization Of Microbial Communities Associated With Intra-oral Halitosis And Exploration Of The Feasibility Of Microbiota Transplantation Therapy

Objective:1.To explore the microbial community composition and metabolic characteristics of different ecological sites in the oral cavity of patients with intra-oral halitosis(IOH);2.To further propose an oral microbiota transplantation(OMT)treatment strategy,and to analyze its feasibility.Methods:7 patients with IOH who visited the First Affiliated Hospital of Xinjiang Medical University with the main complaint of halitosis(group H)and 3 healthy subjects(group N)were randomly selected from patients who visited the hospital from June 2017 to June 2022.Breath values and tongue scores were recorded separately for both groups,and samples of saliva,tongue,buccal mucosa and,jaw mucosa flora were collected.Sixteen SPF-grade Wistar rats were housed in the Animal Experiment Center of Xinjiang Medical University and randomly divided into an experimental group(Group E,8 rats)and a control group(Group C,8 rats)for the flora colonization test.Microbiological and related metabolic analyses were performed in different ecological sites of the oral cavity of the subjects and rats in both groups using the 16Sr RNA sequencing method and PICRUSt metabolic analysis method.Results:1.Group H showed high abundance of Megasphaera in saliva and buccal mucosa samples,Campylobacter in saliva and tongue samples,and Leptotrichia in tongue and buccal mucosa samples(all P<0.05).In addition,the abundance of Dialister and Treponema in saliva,Corynebacterium in the tongue,Prevotella,Lachnoanaerobaculum and Tannerella in the buccal mucosa were also significantly increased(all P<0.05).There was no significant difference in the abundance and diversity of saliva,tongue,buccal mucosa,and jaw mucosa flora between group H and group N(all P>0.05).Adonis analysis suggested that only the salivary flora(R~2=0.175,P=0.011)differed significantly between groups,while the rest of the ecological sites were similar between groups(all P>0.05).Metabolism was significantly enhanced only for cysteine and methionine in saliva,while no significant differences were observed for sulfur and sulfur-containing amino acid metabolism in the remaining three ecological sites(all P>0.05).However,the Phenylalanine metabolic pathway,Pantothenate and Co A(coenzyme)biosynthesis pathways and Tropane,piperidine and pyridine alkaloid biosynthesis pathways were significantly enhanced in the saliva of group H.The Glycosaminoglycan degradation pathway,the One carbon pool by folate pathway,the Nicotinate and nicotinamide metabolism pathway,the Zeatin biosynthesis pathway and the Protein digestion and absorption pathway were significantly enhanced in the buccal mucosa,and the Aminoacyl-t RNA biosynthesis pathway and the Proteasome pathway were also significantly enhanced in the jaw mucosa(all P<0.05).2.In the rat colonization test,the proportions of Porphyromonas,Fusobacterium,Leptotrichia,and Peptostreptococcus were significantly higher in group E post-colonization compared with group C(all P<0.05),and with Gemella both had zero abundance before-colonization,while no colonization was seen in group C post-colonization compared with baseline.PICRUSt metabolic analysis also showed a significantly enhanced IOH-related metabolic pathway in group E post-colonization(all P<0.05),as well as significantly higher breath values compared to baseline and group C(all P<0.0001).After transplantation of salivary flora in group N,the abundance of associated odor-causing bacteria colonized by rats in group E decreased,the associated metabolism was reduced and the breath values decreased significantly.In contrast,salivary flora of group H colonization in group C also differentially altered flora structure and breath values compared to baseline(P<0.05).Conclusion:1.The structure of salivary flora is significantly altered in IOH patients,and the imbalance of oral flora and metabolic alterations are closely related to the occurrence of IOH,and the buccal mucosa may be important ecological sites in addition to saliva and tongue mucosa;2.OMT treatment is a promising green treatment option,but environmental factors and individual differences still cannot be ignored.