Study On Fermentation Of Ganoderma Lucidum Mycelium With High Triterpenoids Production Based On Oleic Acid Induce-and The Effect Of Oleic Acid On Biosynthesis Of Key Enzymes

Ganoderma lucidum is a kind of large medicinal fungi with economic value.Up to date,polysaccharides,terpenoids,steroids,alkaloids,phenolic structured compounds indicating antioxidant,anticancer,anti-tumour,antiviral,antibacterial,anticholinesterase,antifungal,anti-inflammatory,anti-immunomodulatory activities were isolated from Ganoderma lucidum.In this paper,we mainly studied triterpenoids of Ganoderma lucidum which have biological activity.Oleic acid as a exogenous substances can induce high production of triterpenoids of Ganoderma lucidum.We optimized the Ganoderma lucidum mycelium’s fermentation conditions of high triterpenoids production with adding oleic acid.This research shows that the optimal results is:soluble starch 3.4%,fish peptone 0.72%,KH₂PO₄ 0.3%,MgS0₄ 0.15%,VB₁ 0.005%（m/v）,pH5.5,and adding 4.38%（v/v）of oleic acid at the first day of the fermentation.The liquid loading is 100 mL,the inoculation concentration is 10%（v/v）,and the fermentation time is 9 d.And the production of triterpenoids was up to（287.67±3.77）mg/100 mL.Eleven ganoderic acids of Ganoderma lucidum were preliminarily identified by HPLC-ESI-MSⁿ,and their probable ingredients were as following:Ganoderic acid C₂.Lucidenic acid N、Ganoderenic acid B、7,15-dihydroxy-4,4,14-trimethyl-3,11-dioxochol-8-en-24-oic acid、Ganoderic acid A、Ganolucidic acid A、Lucidenic acid A、Ganoderic acid D、Lucidenic acid D、Ganolucidic acid D、Ganoderic acid J。And we analysised the change of production after the oleic acid induction.It was found that most of the triterpenoids of Ganoderma lucidum could increase by oleic acid induction.To characterize the effect of Oleic acid on Ganoderma lucidum biosynthesis,we used quantitative real-time PCR to measure transcription levels of several genes in the synthesis pathway.The results showed that oleic acid could increase the transcription levels of SQS and CYP51 genes which are the key enzyme genes in the synthesis pathway,so that the production of triterpenoids increased.Oleic acid can inhibit the transcription levels of 14a-LDM,so the metabolic pathway of ergosterol will be inhibited,indirectly increase the production of triterpenoids.We used the fermentation tank to expand the culture of Ganoderma lucidum,and we compared shake flask,stirred fermentor,air-lift fermentor.The production of triterpenoids of stirred fermentor was up to（182.28±3.78）mg/100 mL.The production of triterpenoids of air-lift fermentor was up to（245.44±5.12）g/100 mL.In terms of production,shake flask is the highest;while to stirred fermentor and air-lift fermentor,although the prodution islower,but they can greatly improve production efficiency.This result has important significance for the industrial production of Ganoderma lucidum fermentation.