Null mutation in sspA of Cronobacter sakazakii influences its tolerance to environmental stress

Area of Science:

• Food microbiology
• Bacterial stress response
• Molecular biology

Background:

• Cronobacter sakazakii is an opportunistic foodborne pathogen linked to infant formula infections.
• Its pathogenicity may stem from significant stress tolerance, despite manufacturing hurdles.
• Stringent starvation protein A (SspA) is crucial for E. coli survival under stress.

Purpose of the Study:

• To investigate the role of SspA in Cronobacter sakazakii BAA894 stress tolerance.
• To assess the impact of sspA gene knockout on C. sakazakii's resistance to acid, desiccation, and antibiotics.

Main Methods:

• Created an sspA-knockout mutant of C. sakazakii BAA894.
• Assessed acid, desiccation, and antibiotic tolerance of the wild type and mutant strains.
• Performed transcriptome analysis to identify differentially expressed genes in the mutant.

Main Results:

• The sspA knockout decreased acid tolerance but increased desiccation tolerance in LB medium, while decreasing it in M9 medium.
• Minimum inhibitory concentrations for several antibiotics differed between the wild type and mutant strains.
• Transcriptome analysis revealed significant differential gene expression in the mutant, particularly in genes related to metabolism and chemotaxis.

Conclusions:

• SspA plays a complex role in C. sakazakii BAA894 stress tolerance.
• The sspA mutation affects acid and desiccation resistance, as well as antibiotic susceptibility.
• Understanding SspA's function provides insights into C. sakazakii's survival mechanisms in food environments.