Thermotolerance of Cronobacter sakazakii at elevated temperature in real powdered infant formula devoid of maillard reaction: Inactivation Kinetics, and comparative Genomics

Peter MyintzawFollow
Fiona RyanFollow

ORCID

0000-0003-4340-127X

Department

Biological Sciences

Level

Postgraduate

Presentation Type

Oral Presentation

Supervisor

Michael Callanan

Supervisor

Caitriona Guinane

Abstract

Despite advancements in food safety standards and control measures, Cronobacter sakazakii's thermotolerance continues to be a serious public health concern, particularly in powdered infant formula (PIF). This study aims to elucidate the strain-specific variations in C. sakazakiis’ thermotolerance, particularly under the high temperature of 90°C for 20 minutes in a real PIF matrix using distinct strains ( n = 7). A significant variation (p < 0.05) in the δ value (time required for a 1-log10 reduction from an initial population) amongst the strains was observed when heat treatment data were modelled using the Weibull distribution, indicating substantial strain-specific differences in thermotolerance. No visible colour changes were detected in the PIF under the experimental conditions. In silico multi-locus sequence typing (MLST) analysis based on whole-genome sequencing (WGS) identified the strain set as comprising ST1, ST4, and ST8. WGS from this study, alongside 24 publicly available high-quality genomes’ Prokka annotations unveiled a total of 43 thermotolerance-related genes were present across all genomes. Among these, the presence of hspA, yad_1, and yad_2 was enhanced thermotolerance. Additionally, a standalone tblastn search using thermotolerance genomic island (thrB-Q) protein cluster (accession; FR714908.1), unveiled the presence of a complete set of this gene cluster exhibiting enhanced thermotolerance. The results demonstrated that the thermotolerance variability of C. sakazakii was significant and strain-specific differences linked to its genetic content. Such variations in thermotolerance among strains are critical for accurate microbial quantitative risk assessments to mitigate consumer risks associated with PIF.

Keywords:

C. sakazakii, powdered infant formula, thermotolerance, comparative genomic

Start Date

16-6-2025 10:15 AM

End Date

16-6-2025 10:30 AM

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Jun 16th, 10:15 AM Jun 16th, 10:30 AM

Thermotolerance of Cronobacter sakazakii at elevated temperature in real powdered infant formula devoid of maillard reaction: Inactivation Kinetics, and comparative Genomics

Despite advancements in food safety standards and control measures, Cronobacter sakazakii's thermotolerance continues to be a serious public health concern, particularly in powdered infant formula (PIF). This study aims to elucidate the strain-specific variations in C. sakazakiis’ thermotolerance, particularly under the high temperature of 90°C for 20 minutes in a real PIF matrix using distinct strains ( n = 7). A significant variation (p < 0.05) in the δ value (time required for a 1-log10 reduction from an initial population) amongst the strains was observed when heat treatment data were modelled using the Weibull distribution, indicating substantial strain-specific differences in thermotolerance. No visible colour changes were detected in the PIF under the experimental conditions. In silico multi-locus sequence typing (MLST) analysis based on whole-genome sequencing (WGS) identified the strain set as comprising ST1, ST4, and ST8. WGS from this study, alongside 24 publicly available high-quality genomes’ Prokka annotations unveiled a total of 43 thermotolerance-related genes were present across all genomes. Among these, the presence of hspA, yad_1, and yad_2 was enhanced thermotolerance. Additionally, a standalone tblastn search using thermotolerance genomic island (thrB-Q) protein cluster (accession; FR714908.1), unveiled the presence of a complete set of this gene cluster exhibiting enhanced thermotolerance. The results demonstrated that the thermotolerance variability of C. sakazakii was significant and strain-specific differences linked to its genetic content. Such variations in thermotolerance among strains are critical for accurate microbial quantitative risk assessments to mitigate consumer risks associated with PIF.