Isolation, identification and fermentation process optimization of acetylcholinesterase inhibitory activity of endophytic fungus from Laminaria japonica

In this study, Laminaria japonica from Qingdao sea area was used to isolate and purify endophytic fungus.A total of seven strains of endophytic fungi were isolated. Using modified Ellman method to determine the inhibitory rate of ACh E and active strains were identified.Strain ML-X showed the highest AChE inhibitory activity and was identified, by physiologicalbiochemical characteristics and molecular biological techniques of 18 S rDNA sequencing.Based on single factor and orthogonal test, the culture conditions of liquid fermentation of the endophytic fungi were screened out. The results showed that the strain ML-X was confirmed as Geotrichum candidum, and the optimal fermentation conditions were as follows: PS medium was the suitable medium for the strain at pH6.0, incubated with 5% inoculum and 150 m L/500 m L culture volume at 31 ℃ for 8 days.Under these conditions, the strain ML-X exhibited a higher ACh E inhibitory activity, the inhibition ratio of Ach E was 28.91%± 0.25% when the concentration of crude extract from fermentation broth was 5 mg/m L.