Alterations in the Transcriptional Landscape Allow Differential Desiccation Tolerance in Clinical Cronobacter sakazakii

Yu Cao, Katherine Dever, Sathesh Kumar Sivasankaran, Scott V. Nguyen, Guerrino Macori, Ankita Naithani, Gopal R. Gopinath, Ben Tall, Angelika Lehner, Roger Stephan, Shabarinath Srikumar, Séamus Fanning*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Cronobacter sakazakii is a typical example of a xerotolerant bacterium. It is epidemiologically linked to low-moisture foods like powdered infant formula (PIF) and is associated with high fatality rates among neonates. We characterized the xerotolerance in a clinically isolated strain, Cronobacter sakazakii ATCCTM29544T, and compared the desiccation tolerance with that of an environmental strain, C. sakazakii SP291, whose desiccation tolerance was previously characterized. We found that, although the clinical strain was desiccation-tolerant, the level of tolerance was compromised when compared with that of the environmental strain. Transcriptome sequencing (RNA-seq)-based deep transcriptomic characterization identified a unique transcriptional profile in the clinical strain compared with what was already known for the environmental strain. As RNA-seq was also carried out under different TSB growth conditions, genes that were expressed specifically under desiccated conditions were identified and denoted as desiccation responsive genes (DRGs). Interestingly, these DRGs included transcriptomic factors like fnr, ramA, and genes associated with inositol metabolism, a phenotype as yet unreported in C. sakazakii. Further, the clinical strain did not express the proP gene, which was previously reported to be very important for desiccation survival and persistence. Interestingly, analysis of the plasmid genes showed that the iron metabolism in desiccated C. sakazakii ATCCTM29544T cells specifically involved the siderophore cronobactin, encoded by the iucABCD genes. Confirmatory studies using quantitative reverse transcription-PCR (qRT-PCR) determined that, though the secondary desiccation response genes were upregulated in C. sakazakii ATCCTM29544T, the level of upregulation was lower than that in C. sakazakii SP291. All these factors may collectively contribute to the compromised desiccation tolerance in the clinical strain.

Original languageEnglish
Article numbere00830-21
JournalApplied and Environmental Microbiology
Volume87
Issue number24
Early online date13 Oct 2021
DOIs
Publication statusPublished - 24 Nov 2021
Externally publishedYes

Bibliographical note

Funding Information:
We acknowledge the Department of Agriculture, Food, and the Marine (DAFM) (SMART-pif; 13/F/423), and Enterprise Ireland (IP 2015 0380) for funding Y.C. and S.S., respectively. The funders had no role in study design, data analysis, and manuscript preparation.

Publisher Copyright:
© 2021 American Society for Microbiology. All rights reserved.

Keywords

  • Cronobacter sakazakii
  • Desiccation
  • Production environment
  • RNA sequencing

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Ecology
  • Applied Microbiology and Biotechnology

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