Biofilm spatial organization by the emerging pathogen Campylobacter jejuni: comparison between NCTC 11168 and 81-176 strains under microaerobic and oxygen-enriched conditions

Abstract

During the last years, Campylobacter has emerged as the leading cause of bacterial foodborne infections in developed countries. Described as an obligate microaerophile, Campylobacter has puzzled scientists by surviving a wide range of environmental oxidative stresses on foods farm to retail, and thereafter intestinal transit and oxidative damage from macrophages to cause human infection. In this study, confocal laser scanning microscopy (CLSM) was used to explore the biofilm development of two well-described Campylobacter jejuni strains (NCTC 11168 and 81-176) prior to or during cultivation under oxygen-enriched conditions. Quantitative and qualitative appraisal indicated that C. jejuni formed finger-like biofilm structures with an open ultrastructure for 81-176 and a multilayer-like structure for NCTC 11168 under microaerobic conditions (MAC). The presence of motile cells within the biofilm confirmed the maturation of the C. jejuni 81-176 biofilm. Acclimation of cells to oxygen-enriched conditions led to significant enhancement of biofilm formation during the early stages of the process. Exposure to these conditions during biofilm cultivation induced an even greater biofilm development for both strains, indicating that oxygen demand for biofilm formation is higher than for planktonic growth counterparts. Overexpression of cosR in the poorer biofilm-forming strain, NCTC 11168, enhanced biofilm development dramatically by promoting an open ultrastructure similar to that observed for 81-176. Consequently, the regulator CosR is likely to be a key protein in the maturation of C. jejuni biofilm, although it is not linked to oxygen stimulation. These unexpected data advocate challenging studies by reconsidering the paradigm of fastidious requirements for C. jejuni growth when various subpopulations (from quiescent to motile cells) coexist in biofilms. These findings constitute a clear example of a survival strategy used by this emerging human pathogen.

Intrinsic and Extrinsic Aspects on Campylobacter jejuni Biofilms

“…Turonova et al (2015) showed that C. jejuni NCTC 11168 produces biofilm with multilayer type structure, while C. jejuni 81–176 was able to form finger-like biofilm with an open ultrastructure.…”

Detection ofCampylobacterspp. in water by dead‐end ultrafiltration and application at farm level

“…Biofilm consists of population(s) of bacteria, which adhere to a surface and to each other and are enclosed in a network of biopolymers. Bacteria in biofilm are known to be more resistant to detergents and phagocytosis than planktonic bacteria (Hanning et al, ; Reuter et al, ; Teh et al, ; Bronowski et al, ; Turonova et al, ). This may pose a risk of subsequent broiler chicken flocks being exposed to Campylobacter (Teh et al, ).…”

Molecules Autoinducer 2 and cjA and Their Impact on Gene Expression in <b><i>Campylobacter jejuni</i></b>

“…Biofilm formation is influenced by many factors, including QS, the presence of flagella and specific surface proteins, substrate composition, and physicochemical properties of both cells and the substrate [Turonova et al, 2015]. The lack or presence of important nutrients for bacterial metabolism in media can influence the production of signaling molecules and may have an impact on biofilm structure [Zhang et al, 2015].…”