Klebsiella (nee Enterobacter) aerogenes is the first human gut commensal bacterium with a documented sensitivity to the pineal/gastrointestinal hormone melatonin. Exogenous melatonin specifically increases the size of macrocolonies on semisolid agar and synchronizes the circadian clock of K. aerogenes in a concentration dependent manner. However, the mechanisms driving these phenomena are unknown. In this study, we applied RNA sequencing to identify melatonin sensitive transcripts during culture maturation. This work demonstrates that the majority of melatonin sensitive genes are growth stage specific. Melatonin exposure induced differential gene expression of 81 transcripts during exponential growth and 30 during early stationary phase. This indole molecule affects genes related to biofilm formation, fimbria biogenesis, transcriptional regulators, carbohydrate transport and metabolism, phosphotransferase systems (PTS), stress response, metal ion binding and transport. Differential expression of biofilm and fimbria-related genes may be responsible for the observed differences in macrocolony area. These data suggest that melatonin enhances Klebsiella aerogenes host colonization.

Original languageEnglish
Article number110321
Issue number2
StatePublished - Mar 2022

Bibliographical note

Funding Information:
This work was supported by the National Institutes of Health grant number NIH R01 GM118541 (to VMC) and P20 GM130456–02 (to CLS).

Publisher Copyright:
© 2022 The Authors


  • Exponential
  • Klebsiella aerogenes
  • Melatonin
  • RNA sequencing
  • Stationary growth

ASJC Scopus subject areas

  • Genetics


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