Antibiotic induced biofilm formations in Pseudomonas aeruginosa strains KPW.1-S1 and HRW.1-S3 are associated with increased production of eDNA and exoproteins, increased ROS generation, and increased cell surface hydrophobicity

Abstract

Pseudomonas aeruginosa is a medically important bacteria due to its ability to form biofilm and is also an opportunistic pathogen. Pseudomonas aeruginosa has the intrinsic ability to form biofilm as one of the defense mechanisms for their survival. The fact that it can form biofilms on various medical implants makes it more harmful clinically. Although various antibiotics are used to treat Pseudomonas aeruginosa infections, previous studies have shown that sub-MIC levels of antibiotics cause biofilm formation in this type of bacteria. The present study thus deals with the effect of the aminoglycoside antibiotic gentamicin on the biofilm dynamics of two Pseudomonas aeruginosa strains KPW.1-S1 and HRW.1-S3. Biofilm formation was seen to be increasing with increased gentamicin concentrations in growth media. Confocal laser scanning microscopy and scanning electron microscopy accompanied with other biochemical tests deduced that biofilm-forming components like exoproteins, eDNA, and exolipids as exopolymeric substances in Pseudomonas aeruginosa biofilms were increased in the presence of gentamicin. An increase in reactive oxygen species generation along with increased cell surface hydrophobicity was also seen in both strains when treated with gentamicin. The observed increase in the adherence of the cells accompanied by an increase in exopolymeric substances, eDNA, and exolipids may have largely contributed to the increased biofilm production by the Pseudomonas aeruginosa strains KPW.1-S1 and HRW.1-S3 under the stress of the antibiotic treatment.