Basic mechanisms of adhesion crucial for Campylobacter jejuni biofilms

Abstract S1

Presenter: Anja Klannik (Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia)

Biofilms form as microbial communities that attach to various biotic or abiotic surfaces, such as those in food, medical, industrial and natural environments. Campylobacter jejuni are enclosed within a biofilm in a matrix of extracellular polymeric substances that also serve as a barrier to protect the cells from hostile conditions, such as antimicrobial compounds and various hygienic treatments. On wet food processing surfaces with sufficient roughness and topography for attachment, providing nutrients for microbial growth, biofilms become a challenge to food safety and human health, as they persist and become a source of cross-contamination with multi-drug resistant strains. Thus the normally fragile and fastidious microaerophilic planktonic cells of Campylobacter, which have limited hardiness and growth capacity, benefit significantly from their biofilm phenotype. For more than a decade, Campylobacter jejuni has been the leading cause of bacterial gastroenteritis in industrialized countries worldwide, with the incidence and prevalence of campylobacteriosis mostly associated with consumption of undercooked poultry meat, unpasteurized milk, or contaminated water. Our research focuses on understanding the basic mechanisms of adhesion, which is considered the first phase of multistage biofilm formation. To this end, we study planktonic, adherent and biofilm cells using modern molecular approaches and determine gene expression and protein profiles by RNA-seq and mass spectrometry. By linking these data to the physiology of C. jejuni NCNC 11168, we aim to identify key mechanisms as potential targets for innovative control strategies. The starting point is the quantitative evaluation of the adhesion of C. jejuni NCTC11168 to the abiotic surface of polystyrene. The basic mechanisms involved in adhesion were investigated (i) at the metabolic level by characterizing growth, motility, morphology and biomass of the mutants and (ii) at the level of specific cell adhesins by using lectins that bind to the bacterial surface. After the initial phase of adhesion to the polystyrene in the first 12 hours, the number of cells increases slightly up to 24 hours, after which the number of cells in the formed biofilm decreases. By modeling adhesion to polystyrene, we showed that: (i) different cellular mechanisms are involved and that we can modulate both adhesion by affecting efflux pumps and the cell’s stress response by affecting signaling systems, thereby reducing adhesion. Furthermore, using a fungal lectin that specifically binds to outer membrane proteins and extracellular proteins, we demonstrated the involvement of specific adhesins and identified new extracellular matrix molecules involved in adhesion to polystyrene, including: Flagellin A, major outer membrane protein, outer membrane tyrosine kinase, outer membrane fibronectin-binding protein, and amino acid-binding periplasmic protein.

About the presenter

Nationality: Slovene

Academic title: Ph. D., Associate Professor of Microbiology

Address: Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1111 Ljubljana, Slovenia

My scientific interest focused on food-related bacteria, pathogenic Campylobacter, Listeria transmitted via food: Characterization of Campylobacter stress response and subsequent resistance in food against physical / chemical stresses, examined on several cell levels: genetic, proteomic, physiology response; including pathogen-host interactions: modulation of pathogenicity Antimicrobial and resistance-modulatory activity of bioactive agents for the control of food-borne pathogen and spoilage bacteria in vitro and in vivo monitored in food models and in real food system. Biofilm-specific resistant phenotype and persisted cells and influence on bacterial survival, adhesion properties, virulence properties, signalling and bacterial communication. New methods of bacteria quantification: in planktonic form, adhered, in biofilm with PCR-based methods. https://orcid.org/0000-0003-1632-5785 https://www.researchgate.net/profile/Anja-Klancnik The authors contributing the abstrakt are: Anja Klannik, Dina Rami, Meta Sternia, Manca Volk, Bla Jug, Jerica Saboti, Sonja Smole Moina Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia Department of Biotechnology, Joef Stefan Institute, Ljubljana, Slovenia Key words: Campylobacter jejuni, biofilm, adhesion, basic mechanism, adhesin, abiotic surface

Presenting in Speaking session 4 - Survival and application