Project description:Survival and persistence of pathogenic bacteria throughout the food production and supply chain, as well as the zoonoses they cause, represent a major public health concern. Patients with certain chronic diseases have an increased risk of severe infection with the novel coronavirus during the current pandemic, which highlights the urgent need for global control of pathogens, including Campylobacter bacteria, within the food chain. The pathogenic bacteria Campylobacter jejuni are the leading cause of human intestinal infections in developed countries. The incidence of campylobacteriosis is increasing, with the main sources being the consumption of inadequately heat-treated contaminated poultry and pork meat, as well as microbiologically contaminated drinking water. The ability to form biofilms is an important adaptive and defensive mechanism that enables bacterial survival on various surfaces and underlies their persistence and successful transmission, including of strains resistant to multiple antibiotics. A biofilm is a microbial community attached to different abiotic or biotic surfaces, such as materials in the food production chain, medical equipment, or environmental surfaces. On food and food-processing materials, food residues promote biofilm colonization, thereby supporting bacterial survival and creating a continuous source of contamination and host-to-host transmission. This indicates a remarkable and insufficiently explored biofilm dynamic that enables environmentally sensitive planktonic cells—lacking adaptive or survival mechanisms—to develop environmental resistance (the so-called “Campylobacter paradox”). This facilitates transmission from the environment to slaughterhouses, through the food production and distribution chain, or directly via environmental water to humans as hosts. Therefore, understanding the inter-bacterial dynamics of Campylobacter biofilms is crucial for developing new and innovative strategies to limit contamination and/or treat microbial infections. Campylobacter bacteria will serve as a model for developing novel approaches or strategies to reduce such infections through an in-depth understanding of biofilm formation, inter-bacterial communication dynamics within the biofilm, and mechanisms that do not promote antibiotic resistance. The project will first focus on the inter-bacterial dynamics between Campylobacter and probiotic as well as spoilage bacteria. We will identify the genes, key proteins, and fundamental mechanisms essential for bacterial surface attachment and inter-bacterial interactions within the biofilm. Furthermore, we will investigate the poorly defined architecture of Campylobacter biofilms and the structural components of polysaccharides, proteins, and extracellular DNA (eDNA) responsible for structural support and efficient intercellular communication within the microbial community. Since Campylobacter inter-bacterial communication is not well described, our research will target bacterial interactions through signaling molecules and genetic material exchange, enabling us to understand their roles in metabolism and social inter-bacterial interactions during biofilm formation. Understanding biofilm formation processes, together with the development of new strategies to prevent Campylobacter contamination of food, will reduce the transmission of resistance and contribute to safer food production. Additionally, we will define key mechanisms of inter-bacterial communication and biofilm formation, providing insight into bacterial motility, nutrient acquisition, and adhesion to various abiotic (e.g., polystyrene) and biotic (e.g., human cell lines) surfaces. The project will provide a comprehensive understanding of the relationship between biofilm formation, bacterial survival, and virulence, as well as the structure of the biofilm and the role of extracellular polymeric substances (EPS) as “interaction tools” for communication with other bacteria. The findings obtained will improve food handling, preparation, and storage practices, and address knowledge gaps regarding microbiological risks associated with biofilms. Consequently, this will contribute to reducing human and animal morbidity and the high costs linked to the consumption of contaminated food.

Project description:Background: The food-borne pathogen Campylobacter is one of the most important zoonotic pathogens. Compared to other zoonotic bacteria, Campylobacter species are quite susceptible to environmental or technological stressors. This might be due to the lack of many stress response mechanisms described in other bacteria. Nevertheless, Campylobacter is able to survive in the environment and food products. Although some aspects of the heat stress response in Campylobacter (C.) jejuni are already known, information about the heat stress response in the related species C. coli and C. lari are still unknown. Results: The stress response to elevated temperatures (46°C) was investigated by survival assays and whole transcriptome analyses for the strain C. jejuni NCTC11168, C. coli RM2228 and C. lari RM2100. While C. jejuni showed highest thermotolerance followed by C. lari and C. coli, none of the strains survived at this temperature for more than 24 hours. Transcriptomic analyses revealed that only 3 % of the genes in C. jejuni and approx. 20 % of the genes of C. coli and C. lari were differentially expressed after heat stress, respectively. The transcriptomic profiles showed enhanced gene expression of several chaperones like dnaK, groES, groEL and clpB in all strains, but differences in the gene expression of transcriptional regulators like hspR, perR as well as for genes involved in metabolic pathways, translation processes and membrane components. However, the function of many of the differentially expressed gene is unknown so far. Conclusion: We could demonstrate differences in the ability to survive at elevated temperatures for C. jejuni, C. coli and C. lari and showed for the first time transcriptomic analyses of the heat stress response of C. coli and C. lari. Our data suggest that the heat stress response of C. coli and C. lari are more similar to each other compared to C. jejuni, even though on genetic level a higher homology exists between C. jejuni and C. coli. This indicates that stress response mechanisms described for C. jejuni might be unique for this species and not necessarily transferable to other Campylobacter species.

			Action	DRS
	ERR4223710_1.fastq.gz	Fastqsanger.gz
	ERR4223710_2.fastq.gz	Fastqsanger.gz
	ERR4223720_1.fastq.gz	Fastqsanger.gz
	ERR4223720_2.fastq.gz	Fastqsanger.gz
	ERR4223730_1.fastq.gz	Fastqsanger.gz

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