Cold Shock Fail to Restrain Pre-formed Vibrio parahaemolyticus Biofilm

The source of persistent infections can be biofilms that occur naturally on food surfaces and medical biomaterials. Biofilm formation on these materials are likely to be affected by environmental temperature fluctuations and information on noticeable temperature shifts on the fate of pre-formed biofilm is sparse. Changes to pre-formed Vibrio parahaemolyticus biofilm under cold shock (4 {degrees}C and 10 {degrees}C) was explored in this study. We show that V. parahaemolyticus biofilm biomass increased significantly during this cold shock period and there was a gradual increase of polysaccharides and proteins content in the extracellular polymeric matrix (EPS). In addition, we demonstrate that the expression of flagella and virulence-related genes were differentially regulated. The architecture of the biofilm, quantified using mean thickness (MT), average diffusion distance (ADD), porosity (P), biofilm roughness (BR) and homogeneity (H) also changed during the cold shock and these parameters were correlated (P < 0.01). However, the correlation between biofilm architecture and biofilm-related genes expression was relatively weak (P < 0.05). Cold shock at 4 {degrees}C and 10 {degrees}C is not sufficient to reduce V. parahaemolyticus biofilm formation and strategies to reduce risk of foodborne infections should take this information into account.