Purpose: In this study, C. jejuni multispecies biofilms formed with Staphylococcus aureus, Salmonella enterica, or Pseudomonas aeruginosa was characterized to explain multispecies biofilm's protection mechanism.
Methods: The mono- and multispecies C. jejuni biofilms are characterized by bio-chemical and bio-physical techniques, including Confocal Raman spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, contact angle measurement and confocal laser scanning microscopy.
Results: After 4 days exposure to aerobic stress, no viable C. jejuni cells could be detected from monospecies C. jejuni biofilm. In contrast, at least 4.73 log CFU/cm2 of viable C. jejuni cells existed in some multispecies biofilms. To elucidate the mechanism of protection mode, chemical, physical and morphological features of biofilms were characterized. Multispecies biofilms contained a higher level of extracellular polymeric substances with a more diversified chemical composition, especially for polysaccharides and proteins, than monospecies C. jejuni biofilm. Structure of multispecies biofilms was more compact and their surface was >8 times smoother than monospecies C. jejuni biofilm, as indicated by atomic force microscopy. Under desiccation stress, water content of multispecies biofilms decreased slowly and remained at higher levels for a longer time than monospecies C. jejuni biofilm. The surface of all biofilms was hydrophilic, but total surface energy of multispecies biofilms (ranging from 52.5 to 56.2 mJ m-2) was lower than that of monospecies C. jejuni biofilm, leading to more resistance to wetting by polar liquids.
Significance: This knowledge can aid in developing intervention strategies to decrease the survival and dispersal of C. jejuni into foods or environment.