The Glutaredoxin Gene, grxB, Affects Acid Tolerance, Surface Hydrophobicity, Auto-Aggregation, and Biofilm Formation in Cronobacter sakazakii.

Na Ling,Yingwang Ye,Jumei Zhang,Wenjing He,Qingping Wu,Chengsi Li,Haiyan Zeng

doi:10.3389/fmicb.2018.00133

Abstract

Cronobacter species are foodborne pathogens that can cause neonatal meningitis, necrotizing enterocolitis, and sepsis; they have unusual abilities to survive in environmental stresses such as acid stress. However, the factors involved in acid stress responses and biofilm formation in Cronobacter species are poorly understood. In this study, we investigated the role of grxB on cellular morphology, acid tolerance, surface hydrophobicity, auto-aggregation (AAg), motility, and biofilm formation in Cronobacter sakazakii. The deletion of grxB decreased resistance to acid stresses, and notably led to weaker surface hydrophobicity, AAg, and biofilm formation under normal and acid stress conditions, compared with those of the wild type strain; however, motility was unaffected. Therefore, grxB appears to contribute to the survival of C. sakazakii in acid stresses and biofilm formation. This is the first report to provide valuable evidence for the role of grxB in acid stress responses and biofilm formation in C. sakazakii.

Highlights

The Cronobacter genus, formerly known as Enterobacter sakazakii (Iversen et al, 2007), is a group of opportunistic pathogens that cause rare but life-threatening cases of necrotizing enterocolitis, meningitis, cyst formation, intracerebral infarctions, bacteremia, and sepsis in premature neonates and infants with underlying chronic conditions (NazarowecWhite and Farber, 1997; Bahloul et al, 2017; Jung et al, 2017; Sharma and Melkania, 2017)
C. sakazakii identification was performed by API 20E diagnostic strips (BioMérieux, Marcyl’Étoile, France), fusA sequencing and multilocus sequence typing analysis (Joseph et al, 2012).For genetic manipulation, E. coli DH5α and C. sakazakii 1409C1 strains were inoculated in LuriaBertani (LB) medium at 37◦C
Identical growth rates were observed in both strains, suggesting that the absence of grxB did not affect the initial growth rates of C. sakazakii

Summary

Introduction

The Cronobacter genus, formerly known as Enterobacter sakazakii (Iversen et al, 2007), is a group of opportunistic pathogens that cause rare but life-threatening cases of necrotizing enterocolitis, meningitis, cyst formation, intracerebral infarctions, bacteremia, and sepsis in premature neonates and infants with underlying chronic conditions (NazarowecWhite and Farber, 1997; Bahloul et al, 2017; Jung et al, 2017; Sharma and Melkania, 2017). The ability of Cronobacter spp. to withstand adverse acid stresses is one of the key factors responsible for their survival, infection, and pathogenicity. RNA polymerase sigma factor (rpoS) and molecular chaperone hfq facilitate the defense response of cells of C. sakazakii cells to defense against adverse environmental grxB in Cronobacter sakazakii conditions (Álvarez-Ordóñez et al, 2013; Kim et al, 2015). The mechanisms underlying the acid stress response of Cronobacter spp. are poorly understood

Methods

Results

Conclusion