Protein profile of Campylobacter jejuni biofilm cells under temperature and oxygen conditions

Abstract P5

Presenter: Blaž Jug (Biotechnical faculty, University of Ljubljana)

As a human pathogenic intestinal bacteria, Campylobacter jejuni can be transmitted from the environment into the food chain via infected animals or contaminated food. The pathway from environmental contaminant to humans has many hurdles. However, C. jejuni can overcome these and cause campylobacteriosis in humans, the most common bacterial gastrointestinal infection worldwide. Biofilm formation represents one of the most important ways for C. jejuni to survive and protect itself from adverse environmental conditions. Our aim was to determine the protein profile of 48 h mature C. jejuni NCTC 11168 biofilm cells at different temperatures and oxygen conditions. For this purpose, we used whole cell lysates digested with a trypsin/Lys-C mixture and identified by label-free mass spectrometry. Using the molecular approach of defining the whole-cell protein profile as a “fingerprint” of a particular bacterial strain, including biological variation, we gained comprehensive insights into the adaptive response of biofilm cells under suboptimal 30 C microaerophilic and aerobic growth conditions compared to normal 37 C and 42 C microaerophilic growth conditions. The results showed that the main effect of temperature is reflected in an increased presence of stress response proteins in the form of protein biosynthesis (Tuf, ribosomal proteins, IlvD, SerS), iron storage and binding (Ftn, FdxA),) with complete loss of cell motility proteins (FlaB, FliW, FlaC, FlgE) and chemotaxis proteins (CheW, CheY). The effect of oxygen is reflected by increased metabolic activity of the citric acid cycle and activation of oxidation complexes (AhpC). We detected increased expression of DNA stabilisation protein (Hup) under aerobic conditions, but there was no change under different temperature conditions. Interestingly, biofilms growing at 30 C under microaerophilic and aerobic conditions did not show proteins associated with biofilm formation at detectable levels, e.g. cadF, clpP, flaB, luxS, and yet biofilm is produced. This approach allows us to study the environmental adaptations and resistance mechanisms of C. jejuni biofilm cells in relation to various stressors. It will also provide insights into the response of cells within the biofilm and reveal important molecular targets for limiting Campylobacter contamination and thus make food production safer.

Presenting in Speaking session 2 - Pathogenesis