Effect of Matricaria aurea Essential Oils on Biofilm Development, Virulence Factors and Quorum Sensing-Dependent Genes of Pseudomonas aeruginosa

Abstract

The emergence of drug-resistant microorganisms presents a substantial global public health threat. The increase in pathogens resistant to commonly prescribed antibiotics underscores the urgent requirement to explore alternative treatment strategies. This study adopts a novel approach by harnessing natural resources, specifically essential oils (EO), to combat bacterial pathogenicity. The primary aim of this research was to analyze the chemical composition of the aerial part of the Matricaria aurea (M. aureas) EO and evaluate its potential for inhibiting quorum sensing (QS) and disrupting biofilm formation in Pseudomonas aeruginosa (P. aeruginosa). The gas chromatography-mass spectrometry (GCMS) analysis unveiled that α-bisabolol oxide A constituted the predominant portion, comprising 64.8% of the total, with β-bisabolene at 6.3% and α-farnesene at 4.8% following closely behind. The antibiofilm efficacy was observed at concentrations of 0.3, 0.15, and 0.08 mg/mL, demonstrating negligible effects on cell viability. Furthermore, the EO from M. aurea effectively inhibited the formation of P. aeruginosa biofilms by diminishing aggregation, hydrophobicity, and swarming motility. Significantly, the EO treatment resulted in a conspicuous decrease in the production of pyocyanin, rhamnolipid, and extracellular polymeric substances (EPS), along with a reduction in the enzymatic activity of protease and chitinase. The EO effectively hindered QS by disrupting QS mechanisms, resulting in a marked decline in the secretion of N-Acyl homoserine lactone (AHL) molecules and the expression of phazA1 and aprA genes. This investigation offers compelling evidence supporting the potential of M. aurea EO as a promising therapeutic candidate for addressing infectious diseases induced by biofilm formation.

Keywords: Matricaria aurea; Pseudomonas aeruginosa; aprA; biofilm; phazA1; quorum sensing; virulence factors; α-bisabolol oxide A.

Figure 1

Effect of the different concentrations of M. aurea EO on the viable P. aeruginosa cells as measured by the absorbance of the red color resulting from formazan production. *** p ˂ 0.001 compared to control untreated cells.

Figure 2

Percentage of biofilm inhibition of P. aeruginosa after treated with various concentrations of M. aurea EO, as determined by the crystal violet assay. ** p ˂ 0.01 and *** p ˂ 0.001 compared to control untreated cells.

Figure 3

Images of a light microscope (40×) observation for the ability of P. aeruginosa to form biofilm after being treated with M. aurea EO at different concentrations equal to (A): 0.0, (B): 0.08, (C): 0.15, and (D): 0.3 mg/mL.

Figure 4

Images of SEM observation for the ability of P. aeruginosa to form biofilm after being treated with M. aurea EO at different concentrations equal to (A): 0.0, (B): 0.08, (C): 0.15, and (D): 0.3 mg/mL.

Figure 5

Percentage of violacein inhibition production by C. violaceum treated with various concentrations of M. aurea EO. The percentage of violacein inhibition for the untreated culture (control) was considered 0.0%. ** p ˂ 0.01 and *** p ˂ 0.001 compared to control untreated cells.

Figure 6

Effect of the different concentrations of M. aurea EO on the swarming motility (A), aggregation (B), hydrophobicity (C), and EPS production (D) of P. aeruginosa. * p ˂ 0.05, ** p ˂ 0.01 and *** p ˂ 0.001 compared to control untreated cells.

Figure 6

Effect of the different concentrations of M. aurea EO on the swarming motility (A), aggregation (B), hydrophobicity (C), and EPS production (D) of P. aeruginosa. * p ˂ 0.05, ** p ˂ 0.01 and *** p ˂ 0.001 compared to control untreated cells.

Figure 7

Percentage inhibition of pyocyanin (A) and rhamnolipids (B) production, and LasA protease (C) chitinase (D) activity by P. aeruginosa treated with various concentrations of M. aurea EO. The percentage of inhibition for the untreated P. aeruginosa (control) was considered 0.0%, *** p ˂ 0.001 compared to control untreated cells.

Figure 8

The percentage of inhibition of AHL production (A) and the relative mRNA expression of pelA, phaZa1, psl, and aprA genes (B) of P. aeruginosa treated with various concentrations of M. aurea EO. * p ˂ 0.05, ** p ˂ 0.01 and *** p ˂ 0.001 compared to control untreated cells.