The Probiotic Properties of a Strain of Sourdough-derived Lactic Acid Bacteria and Its Effect on the Total Saponins of Acanthopanax senticosus Leaves

The purpose of this paper was to evaluate the probiotic properties of a previously isolated strain HUCM105 from sourdough and its effect on the total saponins of Acanthopanax senticosus leaves. The genus and species was identified by the morphological properties and 16S rDNA gene sequences analysis of strain HUCM105. In order to evaluate the probiotic properties, the number of viable bacteria of the strain HUCM105 was monitored at the acidic environment of pH2.0, pH2.5, and pH3.0 and the 0.5% bile environment incubated for 3 h, respectively, and the change of cholesterol content in the cholesterol-rich medium was determined after fermentation of the strain HUCM105 for 24 h. Subsequently, the aqueous extract of Acanthopanax senticosus leaves was used as the sole substrate, and the number of viable bacteria and the total saponin content of Acanthopanax senticosus leaves were measured under static or shaking incubation for 72 h by the strain HUCM105. The results suggested that the strain HUCM105 was identified as Lactobacillus brevis, and exhibited a good tolerance to acid and bile. The number of viable bacteria had no significant changes in a pH value higher than pH2.5 and 0.5% oxgall for 3 h, respectively. Moreover, the strain HUCM105 could remove 26.4% of the cholesterol in the culture medium supplemented with cholesterol after incubation for 24 h. The number of viable cell of the strain HUCM105 was higher and reached the level of 5×10⁸ CFU/mL through the static or shaking incubation at 24 h in the aqueous extract of Acanthopanax senticosus leaves. Static incubation of the strain HUCM105 had no significant effect on the total saponins content of Acanthopanax senticosus leaves, while shaking incubation could significantly increase the total saponins level. The total saponins content of Acanthopanax senticosus leaves was higher when shaking incubation of the strain HUCM105 for 48 h, and reached 42.6 μg/mL, which was 79.0% higher than that of no strain inoculation. In conclusion, it suggested that the strain HUCM105 exhibited probiotic properties including good tolerance to acid and bile and cholesterol removal ability, could grow well in the aqueous extract of Acanthopanax senticosus leaves and increase the total saponins level of Acanthopanax senticosus leaves, and showed a potential application value as a probiotic candidate strain to develop probiotic fermentation products of Acanthopanax senticosus leaves.