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Abstract - Role of Phenotypic Switching in Stability and Persistence of Pseudomonas aeruginosa Biofilms
Zulfiqar A Mirani, Shaista Urooj, Fouzia Zeeshan Khan, Muhammad Naseem Khan, Mubashir Aziz, Izhar Ahmed Sheikh, Abdul Basit Khan

Role of Phenotypic Switching in Stability and Persistence of Pseudomonas aeruginosa Biofilms

Zulfiqar Ali Mirani1, Shaista Urooj1,2Fouzia Zeeshan Khan3, Muhammad Naseem Khan1, Mubashir Aziz4, Izhar Ahmed Shaikh5, Abdul Basit Khan1

1Microbiology Section-PCSIR Laboratories Complex Karachi, Pakistan

2Department of Microbiology, Federal Urdu University of Arts, Science and Technology Karachi, Pakistan

3Microbiology Dow University of Health Sciences, Karachi, Pakistan

4Department of Pathobiology - Bahauddin Zakariya University, Multan, Pakistan

5PCSIR Laboratories Complex Islamabad, Pakistan



Objectives: Objective: This study was designed to explore the role of different phenotypes of P. aeruginosa in the development, stability and persistence of biofilm.

Methods: A total of seventeen (17) waterborne biofilm producing strains of P. aeruginosa were studied. These isolates were identified on the basis of typical phenotypic characters and the tube method was used for the study of biofilms. Population and phenotypic variance were studied by the drop plate method. The hydrophobicity of strains was evaluated by the bacterial adhesion to apolar solvent test.

Results: Study showed that the subject isolates of P. aeruginosa adopted a biofilm life style after 36 h of incubation at 35 °C. After 24 h the adhesion started, but it was reversible and easily dispersed by simple washing. However, after 36 h the irreversible adhesion was noticed. The biofilm consortia harbor three different phenotypes: i. wild types, showed typical P. aeruginosa characters on Cetrimide agar; ii. Slow growers, showed poor pigmentation and take >36 h for colony development, and iii. Small colony variants (SCVs) are metabolically inactive and producing pinpointed non pigmented colonies. Comparative analysis showed that these phenotypes i.e. SCVs were highly hydrophobic and persistent in biofilm consortia due to the production of excessive amounts of exopolysaccharides.

Conclusions: This study showed that phenotypic heterogeneity is a characteristic feature of P. aeruginosa biofilms and all of these phenotypes have a major role in stability and persistence of biofilm consortia. J Microbiol Infect Dis 2020; 10(1):10-17.

Keywords: Biofilms, Hydrophobicity, P. aeruginosa, Phenotypes, SCVs

Volume 10, Number 01 (2020)