Abstract
To evaluate the novel strategy of oleic acid and fungal elicitor (made from Aspergillus niger) to elicit betulinic acid biosynthesis in medicinal mushroom Inonotus obliquus, we conduct the stimulatory effects investigation for synthesizing betulinic acid from betulin. HPLC results indicated oleic acid and fungal elicitor were effective stimulators. The supplementation of 1.0 g/L oleic acid led to the highest increase of betulinic acid either in dry mycelia or fermentation broth by 2-fold of the control. Fungal elicitor at 45 mg/L markedly increases mycelia growth by 146.0% and enhance intracellular betulinic acid accumulation by 429.5% as compared to the controls. Quantification of transcription levels determined that oleic acid, fungal elicitor and their combinations could induce the expressions of key genes involved in betulinic acid biosynthesis, such as HMG-CoA reductase and squalene synthase. These findings indicated that oleic acid and fungal elicitor could enhance betulinic acid metabolism by up-regulating key genes expression.
Highlights
To evaluate the novel strategy of oleic acid and fungal elicitor to elicit betulinic acid biosynthesis in medicinal mushroom Inonotus obliquus, we conduct the stimulatory effects investigation for synthesizing betulinic acid from betulin
In contrast to the control, oleic acid at the concentration of 1.0 and 2.0 g/L could increase the content of betulinc acid (BA) in wet mycelia by 8.57, 5.63-fold and the concentration of BA in fermentation broth by 3.02, 0.39-fold individually
Oleic acid and fungal elicitor were found to be more effective in promoting mycelial growth and BA’s accumulation among the tested exogenous stimulators than betulin. 1.0–2.0 g/L of oleic acid could lead to a significant increase on mycelia biomass, which was consistent with the mycelia growth of I. obliquus in previous studies [5,7]
Summary
To evaluate the novel strategy of oleic acid and fungal elicitor (made from Aspergillus niger) to elicit betulinic acid biosynthesis in medicinal mushroom Inonotus obliquus, we conduct the stimulatory effects investigation for synthesizing betulinic acid from betulin. Quantification of transcription levels determined that oleic acid, fungal elicitor and their combinations could induce the expressions of key genes involved in betulinic acid biosynthesis, such as HMG-CoA reductase and squalene synthase. As a kind of functional food and traditional Chinese herb, I. obliquus has been utilized for a long time [1] This medicinal mushroom is widely distributed in Asia, North Europe and. Due to its slow growth and rarity in nature, I. obliquus is not a reliable source of industrialized production of betulinic acid Liquid culture of this higher fungus can be a potential substitute for the efficient extraction of BA. Betulin was used stimulatory agent to enhance mycelial biomass and production of exo-polysaccharides from I. obliquus [8] Another potential stimulator may be fungal elicitor, which has been applied in G. lucidum [14]. Some reports suggested that fungal elicitor had Academic Editors: Thomas Edison
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