A Study on the Synbiotic Composition of Bifidobacterium bifidum and Fructans from Arctium lappa Roots and Helianthus tuberosus Tubers against Staphylococcus aureus

Abstract

A number of mechanisms have been proposed explaining probiotics and prebiotics benefit human health, in particular, probiotics have a suppression effect on pathogen growth that can be enhanced with the introduction of prebiotics. In vitro models enhanced with computational biology can be useful for selecting a composition with prebiotics from new plant sources with the greatest synergism. Water extracts from burdock root and Jerusalem artichoke tubers were purified by ultrafiltration and activated charcoal and concentrated on a rotary evaporator. Fructans were precipitated with various concentrations of ethanol. Bifidobacterium bifidum 8 VKPM AC-2136 and Staphylococcus aureus ATCC 43300 strains were applied to estimate the synbiotic effect. The growth of bifidobacteria and staphylococci in monocultures and cocultures in broths with glucose, commercial prebiotics, as well as isolated fructans were studied. The minimum inhibitory concentrations (MICs) of lactic and acetic acids for the Staphylococcus strain were determined. A quantitative model joining the formation of organic acids by probiotics as antagonism factors and the MICs of pathogens (as the measure of their inhibition) was tested in cocultures and showed a high predictive value (R² ≥ 0.86). The synbiotic factor obtained from the model was calculated based on the experimental data and obtained constants. Fructans precipitated with 20% ethanol and Bifidobacterium bifidum have the greater synergism against Staphylococcus.

Keywords: Bifidobacterium bifidum; Jerusalem artichoke tubers; Staphylococcus aureus; burdock roots; coculture; fructans; growth inhibition model; synbiotics.

Figure 1

Curves S. aureus growth inhibition: Comparison of experimental and predicted data. Each specific growth rate value of the pathogen is the average of three measurements (p = 0.05).

Figure 2

The experimental and calculated curves of S. aureus growth in monoculture (orange) and coculture (blue) at different initial cell counts ((A–C)-${\mathit{x}}_{{\mathit{P}\mathit{t}}_0}$ = 10⁶ CFU mL⁻¹; (D–F)-${\mathit{x}}_{{\mathit{P}\mathit{t}}_0}$ = 10⁷ CFUmL⁻¹) and with different substrates ((A,D)-glucose; (B,E)-FOS; (C,F)-lactulose). The curves of the calculated specific growth rates of the pathogen as a function of time (dark blue). To calculate the specific growth rate of the pathogen, the count of bifidobacteria was determined according to the exponential law. The concentration of lactic and acetic acids were defined using the yields values. To calculate the specific growth rate MIC equation was used. The growth curves were built using the calculation results from the MIC model in coculture and the Verhulst equation in monoculture.

Figure 3

Electropherograms of FOS (A), Burd-20 (B) or JA-20 (C) samples; medium before inoculation (1) and cultural fluid after 8 h of fermentation of S. aureus monoculture (2), B. bifidum monoculture (3), and coculture (4). Standards were fructose (FRU), glucose (GLU), and sucrose (SUC). The left group of peaks is suggested to correspond to pure fructose oligomers and the right one to glucose-containing FOS.