EFFECT OF STABLE EXPRESSION OF IBER ON BIOFILM FORMATION OF ESCHERICHIA COLI K1 STRAIN

Abstract

Intro: It has been confirmed that ibeR is a stable regulatory gene of Escherichia coli that participates in the regulation of stress adaptability and virulence gene expression in the stable phase of pathogenic bacteria. Biofilm formation and bacterial invasion are the critical factors of bacterial meningitis caused by Escherichia coli. By comparing the changes of them between ibeR gene mutant deletion strain and wild strain, it was confirmed that ibeR was involved in the biofilm formation of Escherichia coli. Methods: The bacteria were divided into three groups: (1) DH5α, (2) ibeR wild strain, and (3) ibeR knockout mutant strain. Each group's absorbance was read at 600 nm before and after crystal violet staining to calculate the biofilm formation index. Human brain microvascular endothelial cells (HBMECs) were selected to evaluate each bacterial group's invasion of cells. Findings: The biofilm formation index of ibeR wild strain was significantly higher than that of the non-pathogenic Escherichia coli DH5α and ibeR mutant strain (P<0.05). The bacterial invasion rates of ibeR wild strain were significantly higher than that of the non-pathogenic Escherichia coli DH5α and ibeR mutant strain (P<0.05). These results suggested that IbeR expression promotes biofilm formation and participates in HBMEC infection caused by Escherichia coli K1. Conclusion: IbeR gene affects the biofilm formation of Escherichia coli K1 strain. ibeR gene promotes the formation of Escherichia coli biofilm and increases its pathogenicity by changing the invasiveness of bacteria.