Journal Article

Human Gut Bacteria Are Sensitive to Melatonin and Express Endogenous Circadian Rhythmicity

Patel, Akruti G, Paulose, Jiffin K., Cassone, Vincent M., Wright, John M.

2016

Overview

Circadian rhythms are fundamental properties of most eukaryotes, but evidence of biological clocks that drive these rhythms in prokaryotes has been restricted to Cyanobacteria. In vertebrates, the gastrointestinal system expresses circadian patterns of gene expression, motility and secretion in vivo and in vitro, and recent studies suggest that the enteric microbiome is regulated by the host's circadian clock. However, it is not clear how the host's clock regulates the microbiome. Here, we demonstrate at least one species of commensal bacterium from the human gastrointestinal system, Enterobacter aerogenes, is sensitive to the neurohormone melatonin, which is secreted into the gastrointestinal lumen, and expresses circadian patterns of swarming and motility. Melatonin specifically increases the magnitude of swarming in cultures of E. aerogenes, but not in Escherichia coli or Klebsiella pneumoniae. The swarming appears to occur daily, and transformation of E. aerogenes with a flagellar motor-protein driven lux plasmid confirms a temperature-compensated circadian rhythm of luciferase activity, which is synchronized in the presence of melatonin. Altogether, these data demonstrate a circadian clock in a non-cyanobacterial prokaryote and suggest the human circadian system may regulate its microbiome through the entrainment of bacterial clocks.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Aerogenes / Amino Acid Motifs / Bacteria / Bacterial Proteins - physiology / Biological clocks / Biology / Bioluminescence / Care and treatment / Circadian Rhythm / Circadian rhythms / Computational Biology / Cyanobacteria / Databases, Protein / Development and progression / E coli / Enterobacter aerogenes / Enterobacter aerogenes - physiology / Entrainment / Escherichia coli / Escherichia coli - physiology / Eukaryotes / Flagella / Gastrointestinal Microbiome / Gastrointestinal system / Gene expression / Genetic transformation / Humans / In vivo methods and tests / Internet / Intestines - microbiology / Kinases / Klebsiella / Klebsiella pneumoniae - physiology / Luciferases - metabolism / Melatonin / Melatonin - metabolism / Microbiomes / Microbiota (Symbiotic organisms) / Motility / Patient outcomes / Plasmids - metabolism / Pneumonia / Prokaryotes / Proteins / Secretion / Swarming / Synechococcus elongatus / Temperature / Transformation / Vertebrates