Cold Shock Fail to Restrain Pre-formedVibrio parahaemolyticusBiofilm

Abstract

19The source of persistent infections can be biofilms that occur naturally on food surfaces and 20 medical biomaterials. Biofilm formation on these materials are likely to be affected by 21 environmental temperature fluctuations and information on noticeable temperature shifts on 22 the fate of pre-formed biofilm is sparse. Changes to pre-formed Vibrio parahaemolyticus 23 biofilm under cold shock (4 °C and 10 °C) was explored in this study. We show that V. 24 parahaemolyticus biofilm biomass increased significantly during this cold shock period and 25 there was a gradual increase of polysaccharides and proteins content in the extracellular 26 polymeric matrix (EPS). In addition, we demonstrate that the expression of flagella and 27 virulence-related genes were differentially regulated. The architecture of the biofilm, 28 quantified using mean thickness (MT), average diffusion distance (ADD), porosity (P), 29 biofilm roughness (BR) and homogeneity (H) also changed during the cold shock and these 30 parameters were correlated (P < 0.01). However, the correlation between biofilm architecture 31 and biofilm-related genes expression was relatively weak (P < 0.05). Cold shock at 4 °C and 32 10 °C is not sufficient to reduce V. parahaemolyticus biofilm formation and strategies to 33 reduce risk of foodborne infections should take this information into account. 34 35