Functional amyloid of extracellular polymeric substances of marine bacterium Pseudomonas aeruginosa PFL-P1 in the binding of polycyclic aromatic hydrocarbons

Abstract

Increasing level of polycyclic aromatic hydrocarbons (PAHs) in the environment results in environmental pollution. Microbial biofilm-mediated bioremediation has been widely used as an attractive approach to mitigate PAHs contamination in the ecosystem. Amyloid, a proteinaceous component of biofilm-associated extracellular polymeric substances (EPS), forms an integral strengthening part of the biofilm. This study aims to determine the interaction of functional amyloid in Pseudomonas (Fap) with two different PAHs (phenanthrene and pyrene). The production of amyloid by the marine bacterium Pseudomonas aeruginosa PFL-P1 was confirmed by Congo red (CR) assay, thioflavin T (ThT) staining method and amplification of fapC gene. The expression of fapC was up-regulated six folds (p < 0.0001) when phenanthrene and pyrene were used as the sole carbon source. The molecular docking of modelled FapC revealed a strong binding energy of − 7.0 and − 6.75 kcal/mol with phenanthrene and pyrene, respectively. Confocal laser scanning microscopic (CLSM) analysis indicated a significant increase in amyloid percentage during biofilm formation by P. aeruginosa PFL-P1 in the presence of phenanthrene and pyrene (p < 0.0001). The increased expression of the fapC gene and the potent hydrophobic interaction between the FapC protein and the PAH molecules suggest the essential role of this protein in PAH binding.