Characterizing the rhythmic oscillations of gut bacterial and fungal communities and their rhythmic interactions in male cynomolgus monkeys

ABSTRACT The circadian oscillation of gut microbiota plays vital roles in the normal physiology and health of the host. Although the diurnal oscillation of intestinal bacteria has been extensively studied, little relevant work has been done on intestinal fungi. Besides, the rhythmic correlations between bacterial and fungal microbes are also scarcely reported. Here, we investigated the diurnal oscillations of bacterial and fungal communities in male cynomolgus monkeys by performing 16S rRNA and ITS amplicon sequencing. As for bacterial genera, we found that the relative abundance of Prevotella, norank_f_Eubacterium_coprostanoligenes_group, and Peptococcus underwent significant changes at ZT12 (19:00) and exhibited obvious rhythmic oscillations. Consequently, most of the bacterial functions varied at ZT12 and were positively correlated with the bacterial genera norank_f_Eubacterium_coprostanoligenes_group and Prevotella. Among the fungal genera, the relative abundance of Aspergillus and Talaromyces decreased at ZT18 (1:00) and showed slight rhythmic oscillations. As for the fungal function, the undefined saprotroph showed slight rhythmic oscillation and was positively correlated with the fungal genus Aspergillus. Notably, we characterized the correlations between intestinal bacteria and fungi every 6 h over the course of a day and found that the bacterial and fungal microbes interacted closely, with the most bacteria–fungi interactions occurring at ZT12. Our study contributed to a more comprehensive understanding of the diurnal oscillation patterns of bacterial and fungal microbes in male cynomolgus monkeys and uncovered their correlations during a diurnal cycle.IMPORTANCEThe rhythmic oscillation of gut microbiota can impact the physiology activity and disease susceptibility of the host. Until now, most of the studies are focused on bacterial microbes, ignoring other components of gut microbes, such as fungal microbes (mycobiota). Besides, only few studies have addressed the rhythmic correlations between gut bacteria and fungi. Here, we analyzed the rhythmic oscillations of bacterial and fungal communities in male cynomolgus monkeys by performing 16S rRNA and ITS amplicon sequencing. Apart from identifying the rhythmically oscillated bacterial and fungal microbes, we conducted the correlation analysis between these two microbial communities and found that the intestinal bacteria and fungi exhibited close interactions rhythmically, with the most interactions occurring at ZT12. Thus, our study not only investigated the rhythmic oscillations of gut bacterial and fungal communities in male cynomolgus monkeys but also uncovered their rhythmic interactions.