Detoxification of Acrylamide by Potentially Probiotic Strains of Lactic Acid Bacteria and Yeast

Abstract

Some potentially probiotic strains of lactic acid bacteria (LAB) and yeast that inhabit the digestive tract of humans are known to detoxify xenobiotics, including acrylamide (AA). The objective of the subsequent research was to evaluate the AA-detoxification capability of LAB and yeast isolated from various sources. Namely, the effect of AA was tested on the growth of LAB and yeast strains, as well in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Subsequently, the AA-binding ability of LAB and yeast was investigated in various environments, including the pH, incubation temperature, cell density, and with inanimate cells. The ability of selected LAB and yeast to reduce the genotoxicity of AA was tested on Caco-2 and Hep-G2 cell lines. The results showed that all tested strains exhibited strong resistance to AA at concentrations of 5, 10, and 50 µg/mL. Also, AA was detected in the intracellular and membrane extracts of tested strains. The most effective binding strain was Pediococcus acidilactici 16 at pH = 5, cell density = 10⁹ CFU/mL, and incubation temperature = 37 °C (87.6% of AA removed). Additionally, all tested strains reduced the genotoxicity of AA, with the greatest reduction observed at the highest concentration of 50 µg/mL. The phenomena of detoxification by potentially probiotic strains could reduce the toxic and harmful effects of AA exposure to humans every day.

Keywords: DNA damage; MTT assay; acrylamide; bioaccumulation; cell viability; detoxification; lactic acid bacteria; probiotics; yeast.

Figure 1

Heatmaps of lactic acid bacteria (A) and yeast (B) cell growth after acrylamide (5, 10, 50 µg/mL) exposition during 24 h incubation using the spectrophotometric method. Each data point represents the mean from eight individual wells. The evaluation was conducted in two or three independent experiments. The figures were generated using R Studio software, version 4.3.3.

Figure 1

Heatmaps of lactic acid bacteria (A) and yeast (B) cell growth after acrylamide (5, 10, 50 µg/mL) exposition during 24 h incubation using the spectrophotometric method. Each data point represents the mean from eight individual wells. The evaluation was conducted in two or three independent experiments. The figures were generated using R Studio software, version 4.3.3.

Figure 2

Effect of acrylamide (0, 5, 10, 50 µg/mL) on the growth of lactic acid bacteria (A) and yeast (B) strains during 24 h incubation and evaluated using the pour plate method in an appropriate agar medium. The experiment was performed with two repetitions for each strain. The evaluation was conducted with three independent experiments. Results are visualized as dots and represent the mean ± standard deviation (SD), with the significance of the difference from the unexposed control at * p ≤ 0.0332, ** p ≤ 0.0021, and **** p ≤ 0.0001. The figures were generated using R Studio software, version 4.3.3.

Figure 2

Effect of acrylamide (0, 5, 10, 50 µg/mL) on the growth of lactic acid bacteria (A) and yeast (B) strains during 24 h incubation and evaluated using the pour plate method in an appropriate agar medium. The experiment was performed with two repetitions for each strain. The evaluation was conducted with three independent experiments. Results are visualized as dots and represent the mean ± standard deviation (SD), with the significance of the difference from the unexposed control at * p ≤ 0.0332, ** p ≤ 0.0021, and **** p ≤ 0.0001. The figures were generated using R Studio software, version 4.3.3.

Figure 3

Effect of acrylamide (5, 10, 50 µg/mL) on the cell viability of lactic acid bacteria (A) and yeast (B) strains during 24 h of exposure in the MTT assay. Each data point represents the mean from eight individual wells. The evaluation was conducted using two independent experiments. Results are presented as the mean ± standard deviation (SD), with the significance of the difference from the unexposed control at * p ≤ 0.0332, ** p ≤ 0.0021, *** p ≤ 0.0002, and **** p ≤ 0.0001. The figures were generated using R Studio software, version 4.3.3.

Figure 4

Basic endogenous DNA damage in (A) Caco-2 and (B) Hep-G2 after exposure to acrylamide in the presence of lactic acid bacteria and yeast strains, expressed as the mean percentage of DNA in the comet tail in the alkaline comet assay. Fifty cells were analyzed for each treatment. Results are presented as the mean ± standard error of the mean (S.E.M.), with the significance of the difference from the positive control at * p ≤ 0.0332, ** p ≤ 0.0021, and *** p ≤ 0.0002. Positive control 5 µg/mL acrylamide—blue, positive control 50 µg/mL acrylamide—pink, samples with lactic acid bacteria or yeast with addition of 5 or 50 µg/mL acrylamide—black. The figures were generated using GraphPad Prism 10 software.

Figure 5

Representative images of 1 mg/mL PI-stained comets of Caco-2 cells: (A) untreated cells; (B) cells treated with 5 µg/mL acrylamide; (C) cells treated with 50 µg/mL acrylamide; (D) cells treated with 5 µg/mL acrylamide + Pediococcus acidilactici 16; (E) cells treated with 50 µg/mL acrylamide + Lactococcus lactis 3; (F) cells treated with 50 µg/mL acrylamide + Kluyveromyces lactis D2. Fluorescence microscopy; 200× magnification.