Isolation Of An Endophytic Camptothecin-producing Fungus From Camptotheca Acuminata And Selection Of Its Optimal Fermentative Medium

Plant secondary metabolites have a variety of important biological functions,which promise a wide range of applicational prospects in agricultural and industrial production and in human's daily life.Plant alkaloids,which constitute one of the largest groups of natural products,provide many pharmacologically active compounds.Camptothecin (CPT) and its derivatives,which belong to a group of monoterpenoid indole alkaloids, exhibit a significant anti-tumor action.CPT is a kind of alkaloids in Camptotheca acuminata,exhibits a certain of role in plant defence reaction.Endophytes are microorganisms that live in the intercellular spaces of stems,petioles,roots,and leaves of plants.Isolation of endophytes from Camptotheca acuminate may provide a practical solution for the great demand of anticancer drugs in the near future.In our research,thirty-two endophytic fungus strains were isolated by aseptic technique from the inner barks of the medicinal plant,Camptotheca acuminata.After analysis of the fermentation extract by HPLC method,we identified that one strain could produce camptothecin.Based on the morphological identification,the fungus was identified as one of ozonium species.The optimal culture medium selection was studied by orthogonal test.Table L₉(3⁴) was used to test four factors with three levels,and the interaction among the factors was also studied.The results showed that the optimal culture medium for the endophytic fungus consisted of 1%fructose,1%sucrose,0.2% peptone,0.5%yeast powder,KH₂PO₄ 0.5%,0.3%MgSO₄.7H₂O and 0.001%V_B1.As a result of the long-held associations,it is conceivable that some of these endophytic microbes may have devised genetic systems allowing for the transfer of information between themselves and the higher plant and vice versa.Based on the command of key enzyme 3-hydroxy-3-methylglutaryl-Coenzyme A reductase in the metabolism pathway of CPT production,we designed the degenerate primer to analyze the CA1 endophyte on molecular level,provide the evidence for potential CPT production.