AUTHOR=Jiao Xinwei , Li Zhijie 

TITLE=Temporal dynamics and composition of ocular surface microbiota in C57BL/6J mice: uncovering a 12h ultradian rhythm

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2023.1244454

DOI=10.3389/fcimb.2023.1244454

ISSN=2235-2988

ABSTRACT=<sec><title>Purpose</title><p>This study aimed to investigate the presence of rhythmic fluctuations in the composition, abundance, and functions of commensal core bacteria on the ocular surface of C57BL/6J mice.</p></sec><sec><title>Methods</title><p>Male C57BL/6J mice, aged 12 weeks, were subjected to a 12-hour light/12-hour dark cycle. Ocular surface tissue samples were collected at four time points (ZT) over a 24-hour period at six-hour intervals. The core ocular surface microbiota’s oscillation cycles and frequencies were assessed using 16S rRNA gene sequencing targeting the V3-V4 region, along with the JTK_CYCLE algorithm. Functional predictions of these bacteria were conducted using PICRUSt2.</p></sec><sec><title>Results</title><p>Deep sequencing of the ocular surface microbiota highlighted the high abundance of commensal bacteria, with <italic>Proteobacteria</italic>, <italic>Actinobacteriota</italic>, and <italic>Firmicutes</italic> collectively constituting over 90% of the total sample abundance. Among the 22 core bacterial genera, 11 exhibited robust 12-hour rhythms, including <italic>Halomonas</italic>, <italic>Pelagibacterium</italic>, <italic>Pseudomonas</italic>, <italic>Nesterenkonia</italic>, <italic>norank_f_Hyphomonadaceae</italic>, <italic>Stenotrophomonas</italic>, <italic>Anoxybacillus</italic>, <italic>Acinetobacter</italic>, <italic>Zoogloea</italic>, <italic>Brevibacillus</italic>, and <italic>Ralstonia</italic>. Further taxonomic analysis indicated significant intra-cluster similarities and inter-cluster differences at the order, family, and genus levels during ZT0/12 and ZT6/18. Community interaction networks and functional prediction analyses revealed synchronized 12-hour rhythmic oscillations in neural, immune, metabolic, and other pathways associated with symbiotic bacteria.</p></sec><sec><title>Conclusion</title><p>This study demonstrates the presence of ultradian rhythmic oscillations in commensal bacteria on the ocular surface of normal C57BL/6J mice, with a 12-hour cycle. These findings suggest a crucial role for ultradian rhythms in maintaining ocular surface homeostasis in the host.</p></sec>