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Improvement of crude triterpenoid and extracellular polysaccharide production by fermentation of Lignosus rhinocerus under the inducement of different kinds of aqueous herbal extracts

Yan Ma & Xiao-Bin Yu*

The main purpose of this research is to improve the production of crude triterpenoid and extracellular polysaccharide of Lignosus rhinocerus by liquid fermentation to satisfy market demand. As we all known, the low yield of the two bioactive metabolites is a difficult problem for further research. In this paper, eleven aqueous herbal extracts were added to the fermentation of L. rhinocerus to increase the final concentration of the two target products.
According to the ‘one-factor-at-a-time’ method, Radix polygoni multiflora and Chamomile extract were identified to be effective elicitors for the improvement of mycelial biomass, cEPS and crude triterpenoid production. The peak values of mycelial biomass (i.e., 23.97 ± 0.31 g/L) and cEPS (i.e., 6.97 ± 0.56 g/L) were obtained under the concentration of 15 and 5 g/L from Radix polygoni multiflora extract, respectively. Moreover, the maximum crude triterpenoid
production reached 8.72 ± 0.20 mg/g with the addition of Chamomile extract under the concentration of 25 g/L. In order to attain higher production of the total crude triterpenoid, the two optimal aqueous herbal extracts were chosen for the further research. The highest crude triterpenoid production (i.e., 20.32 ± 0.29 mg/g) and the maximum total crude triterpenoid production (i.e., 397.99 ± 5.94 mg/L) were received when the concentration of Radix polygoni
multiflora and Chamomile extract was 25 g/L, which had a 3.66 and 3.05 times increase compared to the control without elicitors. This value is so far the best total crude triterpenoid production obtained in liquid fermentation of L. rhinocerus. This work is useful to the further study of L. rhinocerus for the production of polysaccharides and triterpenoid on large scale.