Isolation and identification of two flavonoid-producing endophytic fungi from Ginkgo biloba L.

Strain ST22 and SX10 isolated from the twigs of Ginkgo biloba L. were found to be able to produce phenolic and flavonoid compounds. They were systematically identified by both morphological and molecular methods. Morphological identification, which employed light microscope and scanning electron microscope, showed that ST22 and SX10 are members of Aspergillus. ITS1-5.8S-ITS2 regions of these two strains were cloned in order to carry out a similarity alignment. ST22 was identified as Aspergillus nidulans and SX10 as Aspergillus oryzae. In addition, the total phenolic and flavonoid contents were measured via UV-spectrophotometry. The total phenolic contents in ST22 and SX10 were 0.1413 +/- 0.0098 and 0.1450 +/- 0.0154 mg/ml, respectively. The amounts of total flavonoids in ST22 and SX10 were 0.01162 +/- 0.0014 and 0.01256 +/- 0.00378 mg/ml, respectively. It was concluded that these two strains may have potential as sources of natural medicines or prodrugs.