Production and characterization of exopolysaccharides from Pseudomonas aeruginosa AG01 with some medical potential applications

Abstract

There is growing interest in the production and characterization of bacterial exopolysaccharides (EPS) because of their diverse range of applications. This study aimed to examine the production of EPS by Pseudomonas aeruginosa AG01, to characterize the produced EPS and its application as antioxidant, antimicrobial, antibiofilm, antitumor, and antiviral activity. The results indicated that the ideal conditions for achieving the highest production of EPS included an incubation period of 96 h, a pH level of 6, and a temperature of 32 °C in a nutrient broth medium. The most efficient sources of carbon and nitrogen for the formation of EPS were found to be galactose, glucose, yeast extract, and peptone. Several functional groups were confirmed to be present by Fourier transform infrared spectroscopy including amino groups, amides, carboxylic acids, hydroxyl groups, and phosphates. In the same respect, EPS has antioxidant activity. Moreover, EPS produced by Pseudomonas aeruginosa AG01 demonstrated antibacterial activity against various Gram-positive, Gram-negative bacteria, and yeast, besides antibiofilm activity about 98.93%, 98.86%, 98.63%, and 97.19% for Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli, respectively as well as anticancer activity against prostate cancer (PC3) and breast cancer (MCF7) cells with IC50 values of 156.41 and 156.41 µg/ml, respectively. Flow cytometry analysis revealed that MCF7 cells treated with EPS at a concentration of 500 µg/ml for 48 h showed a reduction in the percentage of cells in both the G0/G1 and S phases compared to the untreated control MCF7 cells. EPS resulted in apoptosis induction in MCF7 cells using the Annexin V-FITC PI staining method. The findings indicate that EPS demonstrates significant antiviral activity against both the herpes simplex virus (HSV-1) and the hepatitis A virus (HAV). In conclusion, EPS has great potential to be developed as a natural antioxidant or used in medicine and pharmaceuticals.

Keywords: Antibiofilm; Antimicrobial; Antioxidant; Antitumor; Antiviral; FT-IR; HPLC.

Fig. 1

Effect of incubation periods (A), pH (B), and temperature (C) on bacterial biomass and EPS production by Pseudomonas aeruginosa in 100 ml culture media. The values are the means of three replicates with standard deviation (± SD)

Fig. 2

Effect of different carbon (A) and nitrogen (B) sources on bacterial biomass and EPS production by Pseudomonas aeruginosa in 100 mL culture media. The values are the means of three replicates with standard deviation (± SD). Mean values in each column followed by a different lower-case letter are significantly different according to Duncan’s multiple range tests at p ≤ 0.05

Fig. 3

(A) FT-IR spectrum of the purified exopolysaccharide from P. aeruginosa AG01. (B) HPLC analysis of the purified exopolysaccharide from P. aeruginosa AG01

Fig. 4

Antimicrobial efficiency of EPS produced from P. aeruginosa AG01 against gram‑positive, gram‑negative, and fungi

Fig. 5

Antibiofilm efficiency of partially purified EPS produces P. aeruginosa

Fig. 6A

Effect of different concentrations of EPS produced from P. aeruginosa AG01 on normal Vero cell line

Fig. 6B

Effect of different concentrations of EPS produced from P. aeruginosa AG01 on PC3 cell line

Fig. 6C

Effect of different concentrations of EPS produced from P. aeruginosa AG01 on MCF7 cell line

Fig. 7

Cell cycle proportions of EPS-treated MCF7 cells: (A) The cell cycle of MCF7 cells without or with EPS (250 µg/ml) treatment for 48 h was detected by flow cytometry. (B) Quantitative statistics of cells in different periods. Data are expressed as the average of three independent replicates

Fig. 8

Effect of EPS on the expression level of apoptosis and necrosis (A) and flow cytometry analysis with Annexin FITC-A (B)