Study On The Effect And Mechanism Of Nano-TiO₂ On The Growth Of Ophiocordyceps Sinensis

Ophiocordyceps sinensis is a traditional Chinese medicine with extremely important pharmacological value. In recent years, because natural Ophiocordyceps sinensis has been over-collected, this resource was on the brink of extinction. The conflict of shortage led to find natural ophiocordyceps’s substitutes. The isolation and culture of Ophiocordyceps sinensis anamorph is one of the effective ways.Firstly, the features of the asexual fungi strain from Ophiocordyceps sinensis using of solid culture were studied and the effective components using the method of liquid fermentation were determinated Secondly, It was studied that the influence of nano Tio2 on morphology, biomass and the active ingredient of Ophiocordyceps sinensis mycelium by the method of solid medium and liquid fermentation. The conditions of improving biomass fermentation were optimized. Finally, the mechanism of nano-Tio2 on the effect of the growth of Ophiocordyceps sinensis was preliminary explored.The mycelium of Ophiocordyceps sinensis was colorless, smooth or slightly warts and a diaphragm. More single sessile spore cell born at the top of the vegetative hyphae or almost extended as a collateral. The spore production cell was colorless, smooth or slightly warts and a diaphragm liked bottle shape small terrier, needle, gradually pointed upward into a narrow neck. The conidium was colorless, no diaphragm, kidney or oblong. The mycelium morphology of Ophiocordyceps sinensis were similar with detailed report of Hirsutella sinensis.The growth rate of Ophiocordyceps sinensis on the nano-TiO2 medium were faster than basal medium; The formation time of fold colony, ridge height, color of cell secretions were different with strains on the two medium; The mycelium on the nano-TiO2 medium were thicker than base medium under the observation of optical microscope,.The spore were rich and evently scattered around the mycelium in the nano-Tio2 medium. Mycelium were plump, thick, conidium diaphragm, smooth and uniformed adhesion on the spore production cell in the nano-TiO2 medium,but mycelium and conidium were dry and not smooth in base medium; It is found that the mycelium and conidium morphology were inconsistent in different medium.Using single factor experiment to optimize the fermentation conditions. The optimal concentration of nano-TiO2 was lmg/mL in liquid fermentation.The fermentation time was 5 d, the initial pH value was 6.0 and speed was 150 r/min. The best of carbon, nitrogen, inorganic salts were sugar, yeast extract, KH2PO4 and MgSO4.The preliminary study of the mechanism of nano-Tio2 on the effect of the growth of Ophiocordyceps sinensis shows that the nano-TiO2 influenced the synthesis and metabolism of protein and changed the relative content of the different proteins of the mycelium.