Microscopic techniques to evaluate the biofilm formation ability of a marine bacterium Pseudomonas aeruginosa PFL‐P1 on different substrata

Abstract

Biofilm formation in bacteria is strongly affected by the nature of substrata. Different substrata such as glass, polystyrene, steel, ceramic, and rubber were used to assess the biofilm forming ability of a marine bacterium Pseudomonas aeruginosa PFL‐P1 using a scanning electron microscope (SEM), atomic force microscope (AFM), and confocal laser scanning microscope (CLSM). The bacterium formed dense biofilms with varied aggregation on different substrata. SEM study revealed small rod‐shaped cells with diverse arrangements within the biofilms on all the substrata under study. The AFM study revealed the highest roughness of 545 nm on the ceramic substratum. The biofilms formed on ceramic substratum were characterized with maximum roughness (742 nm), maximum peak height (1,480 nm), and maximum arithmetic mean height (611 nm), significantly higher than all the other substrata (p < .05). AFM studies confirmed that P. aeruginosa PFL‐P1 exhibited biofilm heterogeneity on all the substrata. The CLSM study indicated a higher fraction of nucleic acids to α‐polysaccharides ratio in the biofilms. COMSTAT analysis revealed the highest biofilm biomass of ~18 μm3/μm2 on the ceramic substratum. The maximum biofilm thickness of ~50 μm in the native state on the ceramic substratum was significantly higher than glass (p = .0015), polystyrene (p = .0001), steel (p = .0035), and rubber substrata (p = .0001). The higher surface roughness of ceramic substratum is accountable for more area for colonization, as evident from higher biomass and thickness of the biofilm. This study provides insight into the substratum properties, which modulate the biofilm forming ability in bacteria.

Vertical growth dynamics of biofilms

“…The characterization of microbial topographies is a growing field ( 31 – 38 ) but with limited focus on the temporal dynamics of the colony. The experimental difficulty in measuring biofilm heights with sufficient precision over many different time scales in a nondestructive manner has limited our understanding of this fundamental phenomenon ( 39 ).…”

Pseudomonas aeruginosa Isolates from Water Samples of the Gulf of Mexico Show Similar Virulence Properties but Different Antibiotic Susceptibility Profiles than Clinical Isolates

“…Biofilm is the major mode of bacteria life in the environment, including the marine habitats, enabling the formation of complex microbial communities [ 74 , 75 ]. Several studies have reported that marine strains of P. aeruginosa are capable of forming biofilm [ 76 , 77 ]. Furthermore, our results indicate that the marine and clinical isolates of P. aeruginosa tested express factors related to the virulence of this bacterium (secretion of ExoS and ExoU toxins through the T3SS, as well as production of pyocyanin, elastase, and rhamnolipids).…”

Vertical growth dynamics of biofilms

“…The characterization of microbial topographies is a growing field( Dervaux et al, 2014 ; Larimer et al, 2016; Kesel et al, 2017 ; Werb et al, 2017 ; Schiebel et al, 2020 ; Paula et al, 2020 ; Hayta et al, 2021; Mahto and Das, 2021 ), but with limited focus on the temporal dynamics of the colony. The lack of clarity about vertical growth dynamics is due in part to the experimental difficulty in measuring the height of a biofilm with sufficient precision over many different time scales in a non-destructive manner( Huang et al, 2020 ).…”

“…The characterization of microbial topographies is a growing field(31–38), but with limited focus on the temporal dynamics of the colony. The lack of clarity about vertical growth dynamics is due in part to the experimental difficulty in measuring the height of a biofilm with sufficient precision over many different time scales in a non-destructive manner(39).…”

“…The characterization of microbial topographies is a growing field (Dervaux et al, 2014;Larimer et al, 2016;Kesel et al, 2017;Werb et al, 2017;Schiebel et al, 2020;Paula et al, 2020;Hayta et al, 2021;Mahto and Das, 2021), but with limited focus on the temporal dynamics of the colony.…”