부산대학교 도서관

The ability of bacteria to attach and grow on virtually any surface poses a tremendous challenge to industries and to human health. There are innumerable species of human pathogens capable of forming biofilms. One such pathogenic species is Campylobacter jejuni - a bacterium well known for causing foodborne illness around the globe. The goal of this research project was to study the effects of environmental and genetic factors on biofilm formation of C. jejuni with the use of mathematical modelling, experimental and bioinformatics techniques. A novel mathematical model of biofilm formation was developed in order to reveal potential reasons about the mechanisms involved and their importance in the ability of C. jejuni to form biofilm communities under various environmental conditions. Through analysis of the output generated by our numerical simulations, we proposed arguments for some puzzling observations regarding C. jejuni biofilm formation which have been previously reported. The effect of different media and atmospheric conditions on biofilm formation of C. jejuni ATCC33291 strain was also investigated experimentally. Growth was enhanced in microaerobic conditions compared to aerobic conditions in all media tested for this particular strain and media. Furthermore, our results suggest that it is more likely that composition of media along with the interactions between specific ingredients determine the extent of biofilm formation, rather than simply the level of nutrients, as has been previously postulated in literature. A Genome wide association study (GWAS) was conducted to unveil potential genetic factors influencing biofilm formation ability of C. jejuni across its phylogeny. A number of genes and SNPs have been identified which may play a role in biofilm formation of C. jejuni. The results obtained may guide future investigations to understand the molecular mechanisms behind C. jejuni biofilm formation. This study adds to the current knowledge of C. jejuni biofilm formation ability. The model presented in this work may be tuned further to include more processes or dimensions and its analysis may be extended to studies of how bacterial cell properties may affect biofilm formation. Our experimental results highlight the importance of interactions between particular ingredients of media on biofilm formation and challenge the previous idea that C. jejuni biofilm growth may be enhanced by low nutrient media, and thus may motivate further studies in this area. Finally, the GWAS study presented here suggests candidates for further analysis of the effect of gene manipulation on biofilm formation of Campylobacter jejuni. Recognition of genetic markers associated with biofilm forming ability of C. jejuni mayinform strategies designed to reduce the burden of this pathogen at food processing stages as well as propose targets for drug development to reduce its host colonisation capabilities.