Effects of Lmo2672 deficiency on environmental adaptability, biofilm formation, and motility of listeria monocytogenes

Abstract

Background: Listeria monocytogenes is a food-borne pathogen with strong environmental adaptability. It can survive at high temperatures and in acidic high-salt and other unfavorable stressful environments and consequently form a biofilm. Objectives: This study aimed to explore the roles of lmo2672 on the environmental adaptability, biofilm formation, and motility of L. monocytogenes. Methods: We analyzed the molecular characteristics of lmo2672 protein, constructed a lmo2672 gene deletion strain of L. monocytogenes strain (L. monocytogenes-∆lmo2672), using the homologous recombination technique and compared the environmental adaptability, biofilm formation, and motility of L. monocytogenes-∆lmo2672 with its parental strain L. monocytogenes EGD-e. The impacts of lmo2672 gene deficiency on the transcription of genes associated with flagella formation and the environmental adaptability of L. monocytogenes were also determined. Results: The results showed that the lmo2672 contains two helix-turn-helix (HTH) DNA-binding domains. Compared to L. monocytogenes EGD-e, L. monocytogenes-∆lmo2672 grew significantly slower at different temperatures (37°C and 42°C) under different osmotic pressures (5% and 8% NaCl) and in different media containing 0.3% bile salts, 5 mM H2O2, or 1% Triton X-100 (P < 0.05). Moreover, LM-∆lmo2672 showed a significant decrease in biofilm formation (P < 0.01) and motility (P < 0.05) at 48 h of culture. Furthermore, the transcriptional levels of regulatory gene prfA and flagella-related genes motA, fliP and fliE significantly decreased in LM-∆lmo2672 (P < 0.05). Conclusions: In general, these findings indicated that lmo2672 played critical regulatory roles in the environmental adaptability, biofilm formation, and motility of L. monocytogenes, thus providing new insights into the regulatory mechanism of lmo2672 in L. monocytogenes.