ABSTRACTCampylobacter jejuniis a microaerophilic bacterium and is believed to persist in a biofilm to antagonize environmental stress. This study investigated the influence of environmental conditions on the formation ofC. jejunibiofilm. We report an extracellular DNA (eDNA)-mediated mechanism of biofilm formation in response to aerobic and starvation stress. The eDNA was determined to represent a major form of constitutional material ofC. jejunibiofilms and to be closely associated with bacterial lysis. Deletion mutation of the stress response genesspoTandrecAenhanced the aerobic influence by stimulating lysis and increasing eDNA release. Flagella were also involved in biofilm formation but mainly contributed to attachment rather than induction of lysis. The addition of genomic DNA from eitherCampylobacterorSalmonellaresulted in a concentration-dependent stimulation effect on biofilm formation, but the effect was not due to forming a precoating DNA layer. Enzymatic degradation of DNA by DNase I disruptedC. jejunibiofilm. In a dual-species biofilm, eDNA allocatedCampylobacterandSalmonellaat distinct spatial locations that protectCampylobacterfrom oxygen stress. Our findings demonstrated an essential role and multiple functions of eDNA in biofilm formation ofC. jejuni, including facilitating initial attachment, establishing and maintaining biofilm, and allocating bacterial cells.IMPORTANCECampylobacter jejuniis a major cause of foodborne illness worldwide. In the natural environment, the growth ofC. jejuniis greatly inhibited by various forms of environmental stress, such as aerobic stress and starvation stress. Biofilm formation can facilitate the distribution ofC. jejuniby enabling the survival of this fragile microorganism under unfavorable conditions. However, the mechanism ofC. jejunibiofilm formation in response to environmental stress has been investigated only partially. The significance of our research is in identifying extracellular DNA released by bacterial lysis as a major form of constitution material that mediates the formation ofC. jejunibiofilm in response to environmental stress, which enhances our understanding of the formation mechanism ofC. jejunibiofilm. This knowledge can aid the development of intervention strategies to limit the distribution ofC. jejuni.
Frontier exploration for gold-based nanostructures for photothermal bacterial lysis
