Studies On Mogroside Ⅴ Producing Endophytic Fungus From Siraitia Grosvenorii

Siraitia grosvenorii, belonging to the family of Cucurbitaceae. Its traditional medicinal and edible value has been confirmed. Mogrosides, a group of triterpenoid glycosides isolated from Siraitia grosvenorii fruit, was a kind of low-calorie,high-sweet, healthy and natural sweetener. Mogroside V is the main component,with a content of 0.5%-1.4% in the dried fruit of Siraitia grosvenorii. It is a cucurbitane-type triterpenoid glycoside isolated from the fruits of Siraitia grosvenorii. Endophytic fungi are live in plants but during their life cycle they do not cause noticeable symptoms of disease to plant tissues,and the host tissues always keep its intaction and function. Endophytic fungi are also known as important resources for producing secondary metabolites. Sometimes, endophytic fungi can produce the same active compounds as their host plants. When endophytic fungi be found in some plants, people were expecting to find suitable endophytic fungi that can product useful metabolites, so endophytic fungi were important biological resource. Thus, if fermentation of endophytic fungi isolated from Siraitia grosvenorii could produce the same secondary metabolites, such as mogroside V, this will be an easier and more available source than plants.In this study, endophytic fungi isolated from Yongfu county in Guangxi province, were identificated by morphological and molecular biology methods, determined mogroside V yield and optimized the fermentation condition. Now the main research achievements are summarized as follows:1. Isolation and culture of endophytic fungi.Total of 15 endophytic fungi isolated from S. grosvenorii,4 strains isolated from leaves,4 strains isolated from stems,2 strains isolated from roots,5 strains isolated from fruit.2. Screening of m mogroside V producing endophytic fungus. Mogroside V was analyzed by HPLC. The presence of mogroside V in the sample was detected by comparing the retention time with that of the standard. The amount of mogroside V in the sample was calculated by the regression of the standard mogroside V curve. And mogroside V-producing fungi were screened (LHG-F5 and LHG-L4, the production of mogroside V reached 7.156μg/mL).The presence of mogroside V in the fungal samples was analyzed by LC-MS3. Identification of endophytic fungi.The two Mogroside Ⅴ-producing purified endophytic fungus were evaluated by the phylogenetic analysis of their ITS-rDNA sequences. According to ITS-rDNA sequences analysis, the mogroside Ⅴ-producing fungi were identified as Diaporthe angelica(LHG-F5) Fusarium solani (LHG-L4).4. The fermentation conditions optimize of mogroside V producing fungi. The nutrition factors and environment factors were optimized by single factor index and orthogonal experiment, The result display the best suitable condition of LHG-F5 is lOg/L glucose,2.5g/L (NH4)2SO4,5 days fermentation,30℃,150 mL contain, pH 7. The yield of mogroside V reached 7.156μg/mL, the yield was 1.87 times than before optimization.