Isolation, characterization and inhibiting effects of Pseudomonas aeruginosa phages as an antibiofilm agent on formation of biofilm

Pseudomonas aeruginosa is a pathogenic microorganism that forms biofilms by adhering to various surfaces, and these biofilms play a significant role in many different sectors such as medicine, industry, and commercial systems. Due to its natural structure and the presence of inactive cells within the biofilms, this microorganism is resistant to antibiotics and various chemical substances, making it difficult to eliminate the biofilm structure. Many different industries such as medicine, food, water, dairy, wine, maritime, and power plants are exposed to biofilm formation. These microbial cells containing extracellular polymeric substances colonize living and non-living surfaces, posing a serious problem for all industries by affecting their processes, reducing product quality, and causing economic losses. Traditional methods used to remove biofilm, such as antibiotics and disinfectants, are generally ineffective. The high dosage of antimicrobial chemicals used to remove biofilms leads to environmental issues in industrial systems and hinders applications in the medical field. Although many industries are aware of this threat, controlling biofilm formation is a challenging process. This situation necessitates further research on improving and controlling biofilms. The aim of this thesis study is to isolate and characterize lytic bacteriophages specific to Pseudomonas aeruginosa, which cause untreatable diseases, commercial and economic losses in both global and national medical and industrial fields due to biofilm formation. The study also aims to investigate the effects of phages and antibiotics used in combination with phages on the biofilm structure formed by the bacteria and explore their potential as an alternative method. Pseudomonas aeruginosa strains isolated and characterized from wastewater in Mersin province showed strong biofilm formation capacity. It was observed that the use of lytic bacteriophages as a preliminary treatment before the occurrence of biofilm formation reduced the density of the resulting biofilm structure, but lytic bacteriophages applied after mature biofilm formation were not effective in eradicating the biofilm structure. It was found that the potential of phage-antibiotic combinations applied after surface biofilm formation of Pseudomonas aeruginosa strains was more effective than using phages alone as therapeutic agents. Our study not only contributes to the characterization of lytic Pseudomonas aeruginosa bacteriophages but also serves as a foundation for future research aimed at improving and controlling the resilient biofilm structures formed by the bacterium.