Effect of cold treatment on biofilm formation ability of Listeria monocytogenes

ObjectiveTo study the effects of cold treatment on the biofilm formation ability of Listeria monocytogenes from different food sources and different serotypes, and provide evidence for the control of L. monocytogenes in food.

MethodsThe biofilm formation ability of L. monocytogenes isolates under 37 ℃, 4 ℃ cold stress and 4 ℃ cold adaptation was determined by crystal violet staining, the analyses on gene sequence and the differences in expression levels of the biofilm formation related genes hpt, luxS and sigB of representative strains were carried out.

ResultsAt 37 ℃, the biofilm formation ability of 1/2c serotype L. monocytogenes was stronger, and no strains with weak biofilm formation ability were observed. At 37 ℃, in the strong biofilm formation ability group (3 strains) and middle biofilm formation ability group (10 strains), 9 strains showed non-synonymous mutations in hpt gene. Under cold treatment conditions, among the 4 middle group strains, 1 strain showed high expression level of sigB gene, and 3 strains showed high expression level of hpt gene.

ConclusionThe biofilm formation ability of L. monocytogenes is related to serotype. The 1/2c serotype strain has stronger biofilm formation ability at 37 ℃. hpt gene mutant strain has stronger biofilm formation ability at 37 ℃, cold treatment reduces the biofilm formation ability of pathogens but the overexpression of hpt and sigB genes enhances the biofilm formation ability of L. monocytogenes at 4 ℃.