[Construction and characterization of Listeria monocytogenes deltahfq mutant strain]

Gram-positive brevibacterium Listeria monocytogenes (Lm) is an important zoonotic foodborne pathogen, engaged in both saprophytism and parasitism. It could adapt, survive and display pathogenicity under different environmental stress challenges, which is associated with the regulatory network consisting of regulating factors. The biological characterizations of regulator hfq was evaluated in this study.

hfq deleted serovar 1/2 a strain EGDe was constructed with homologous recombination, the biological characteristics of the mutant strain was compared with its parental strain.

The growth of EGDe delta hfq was significantly inhibited under cold temperature (P < 0.05), salt medium containing 7% NaCl and the medium containing 4.5% ethanol. The ability of biofilm formation of the mutant strain in BactoTM Brain Heart Infusion (BHI) was reduced significantly (P < 0.05); notably, the invasion rate to Caco-2 cell lines was obviously reduced. Infection capacity of EGDe delta hfq to BALB /c mice decreased and the LDD was 6 times higher than EGDe.

Hfq protein of Listeria monocytogenes plays an important role in regulating bacterial virulence, biofilm formation and stress response. This deletion strain provided material to further study the function of Hfq and provides the possibilities to elucidate the mechanisms of Lm in resisting the stress and paves ways to the development of novel strategies for the prevention and control of Lm infections.