Fungi RE7 Antimicrobial Active Metabolite Research Students Within Licorice

Glycyrrhiza uralensis, a frequently used herb, which has many kinds of bioactive constituents, and has been identified as an endangered medicinal plant by the government because of excessive exploitation. Many studies confirmed that endophytic fungi in plants could produce the same or similar active metabolites as their hosts. As a result, the endophytic fungi resources were developed and utilized in medicinal plants would bring significant ecological and economic benefit.In this paper, an endophytic fungi RE7was isolated from Glycyrrhiza uralensis, which had high activities to antimicrobial. RE7strain was identified by morphological characteristics and18SrDNA sequence analysis. The results indicated that RE7strain belongs to Moniliales Verticillium.Orthogonal experiment was used to study on the fermentation condition of RE7strain, Listeria monocytogenes was chosen as test bacterial. The results are as follows: The optimized cultural condition was that2.0%glucose of carbon source,0.5%peptone of Nitrogen source,30℃of fermentation temperature,140r/min of rotation,40%of medium liquid volume,5%of inoculation amount,7.0of initial pH value. The diameter of antimicrobial activity in the best fermentation condition is increased to20.3±0.5mm than which in initial fermentation condition.Furthmore, RE7strain was fermented in large amount under the optimal fermentation conditions, during active compounds were isolating, they were detected by antibacterial, and two compounds were obtained by macroporous resin, silica gel column chromatography and TLC.The structures of two compounds were analyzed by means of HPLC and1H-NMR, and Crystal A was Glycyrrhetinic acid, but the structure of Crystal B can not be determined for little amount. The antimicrobial results indicated that the Crystal A had antimicrobial activity to5strains.In this work, the active metabolites of Glycyrrhiza uralensis endophytic fungi RE7were initially separated and purified, and compound isolated from the active metabolites was Glycyrrhetinic acid.