Abstract:Endophytic fungi were isolated from junggar hawthorn fruit using a tissue block method and identified by morphological and molecular biology methods.Agar block method and filter paper were used to screen fungal strains for antibacterial activity.Thin layer chromatography（TLC）was used for preliminary analyses of active components in fermentation broths.After identifying effective antibacterial fractions，the content of the active fractions was determined by high performance liquid chromatography （HPLC）.Fourteen strains of endophytic fungi were isolated，included SZ-C strains which produced conditioned media with strong antibacterial activity against Staphylococcus aureus and Escherichia coli.TLC results showed that the SZ-C conditioned media contained quercetin and kaempferol.HPLC analyses indicated that quercetin and kaempferol content were 1.253 mg/L and 1.329 mg/L.According to morphological characteristics and molecular biological analysis，SZ-C was identified as a very small Streptococcus bacteria.The results also indicated the presence of endophytic fungi in junggar hawthorn fruit that possess certain antibacterial effects and could produce quercetin and kaempferol.