The oral microbiota disorder in the GC patients revealed by 2bRAD-M

Abstract

Abstract Background Microbiota alterations are linked with gastric cancer (GC). However, the relationship between the oral microbiota (especially oral fungi) and GC is not known. In this study, we aimed to apply 2bRAD-M to characterize the oral microbiota in GC. Methods We performed 2bRAD-M analysis in saliva and tongue coating of GC patients and healthy controls. We carried out the diversity, relative abundance, and composition analyses of saliva and tongue coating bacteria and fungi of the two groups. In addition, indicator analysis, the Gini index, and the mean decrease accuracy were used to find GC oral fungal indicator. Results In this study, fungi imbalance of saliva and tongue coating were observed in GC group. At the species level, enriched salivary and tongue coating Malassezia globosa (M. globosa) and decreased Saccharomyces cerevisiae (S. cerevisiae) were observed in the GC group. Random forest analysis indicated that salivary and tongue coating M. globosa could serve as a biomarker to diagnose gastric cancer. The Gini index and mean decrease in accuracy of saliva and tongue coating M. globosa are the largest. In addition, Saliva and tongue coating M. globosa classified GC from the control with an area under the receiver operating curve (AUC) of 0.976 and 0.846, respectively. Further ecological analysis revealed the correlations between oral bacterial and fungi. Conclusion For the first time, our data suggested that changes in oral fungi between GC and control may help deepen our understanding of the complex spectrum of the different microbiotas involved in the GC development. Although the cohort size is small, this study is the first to use 2bRAD-M to reveal that oral M. globosa can be a fungal biomarker for detecting GC.