Optimization of Fermentation Conditions and Product Identification of a Saponin-Producing Endophytic Fungus

Abstract

Background: Some fungal endophytes isolated from P. ginseng may present a new method of obtaining saponins. This experiment aimed to optimize the total saponin yield produced through in vitro fermentation by an endophytic fungus and analyze its saponin species in the fermented extract. Methods: Fermentation protocols were optimized with a uniform design and verified through regression analysis to maximize the total saponin yield. The saponin types under optimal fermentation conditions were then identified and analyzed using Liquid Chromatography–Mass Spectrometry. Results: The Trametes versicolor strain NSJ105 (gene accession number: OR144428) isolated from wild ginseng could produce total saponins. The total saponin yield could be increased more than two-fold through the optimization of fermentation conditions. The concentration of the total saponins achieved by the verified protocol 105-DP was close to the predicted value. The fermentation conditions of the 105-DP protocol were as follows: potato concentration 97.3 mg/mL, glucose concentration 20.6 mg/mL, inoculum volume 2.1%, fermentation broth pH 2.1, fermentation temperature 29.2 °C, and fermentation time 6 d. It was detected and analyzed that the fermented extract of 105-DP contained the ginsenosides Rf and Rb3. Conclusion: The endophytic fungus Trametes versicolor strain NSJ105 has potential application value in saponin production.

Fermentation, Identification, and Antioxidant Activity of Saponins Produced by a Wild Ginseng Endophytic Fungus Umbelopsis dimorpha Strain NSJG

“…Twenty types of saponin standards could be detected within 30 min by Liquid Chromatography/Mass Spectrometry (LC/MS) in our previous experiment, of which peaks were complete [34]. The saponin types of G-ED-8 and G-DP-8 fermentation extracts were identified according to these 20 saponin standards.…”

“…A control solution consisting of sample-free reaction solution was prepared as a blank, and the absorbance of the test sample was determined at 544 nm. The concentration of total saponins in the sample was subsequently calculated using the calibration curve [34].…”

“…The Accucore C18 analytical column (2.6 µm, 150 mm × 2.1 mm) was utilized to detect saponins, eluted with deionized water as Mobile Phase A and acetonitrile as Stationary Phase B. The chromatographic profile was designed as a programmed gradient, comprising 0-13 min with 77-54% A; 13-33 min with 54-32% A; 33-45 min with 32% A; 45-55 min with 32-0% A; 55-60 min with 0% A; and 60-63 min with 0-77% A [34]. The flow rate was set to 0.3 mL/min, and an injection volume of 10 µL was employed.…”

“…During the experiment, a 4 µL injection volume was used for both the sample to be tested and the standard sample. The standard sample contained 20 saponins at a concentration of 0.2 mg/mL [34].…”

Biotransformation of American Ginseng Stems and Leaves by an Endophytic Fungus Umbelopsis sp. and Its Effect on Alzheimer’s Disease Control

“…The saponin types of standards, CK-SL, and G-SL were determined by LC/MS. All saponin standards can be detected within 30 min [33]. According to Figure S2 and Table 1, the extract of CK-SL contained 15 kinds of ginsenosides.…”