Isolation And Identification Of The Endophytes From Atractylodes Macrocephala Koidz.and Anti-fungal Activities Of Its Fermentation Products

Endophytic bacteria is a special microorganism that coexists in various tissues of the plant such as roots,stems and leaves.They co-evolve with plants and form a metabolic pathway different from soil microorganisms,which can produce a large number of novel chemical structures and antibacterial effect that has good bacteria effect or biological active substance with special effects.So it can be used as an important resource for the screening of new microbial pesticides.In this paper,the characteristic Chinese medicinal Atractylodes macrocephala Koidz.from Qimen County,Huangshan City was selected as the research object.The endophytic bacteria were isolated from the underground rhizomes of wild healthy plants with the microbial separation and purification technology.Meanwhile,the biological activity of endophytes against various plant pathogenic bacteria were evaluated using flat-panel confrontation method and filter paper bacteriostatic method.The main research results are as follows:1.Isolation and purification of the endophytic bacteria from A.macrocephala Koidz.Using surface disinfection and tissue separation and culture methods,15 strains of endophytic bacteria and 8 strains of endophytic fungi were isolated and purified from the healthy wild underground rhizome of A.macrocephala Koidz.Meanwhile,the confrontation test was used to test the inhibitory effect of endophytes on the plant pathogens such as Phytophthora capsici,Phytophthora sojae,Colletotrichum coccodes,Curvularia lunata,Fusarium oxysporum,and Fusarium graminearum.The results show that 23 endophytes have inhibitory activity on at least one of these plant pathogens.And one strain of endophytic bacteria named QBZ-1 have a significant inhibitory effect on P.sojae and F.verticillioides.2.Isolation and purification of the endophytic bacteria from A.macrocephala Koidz.The endophytic bacteria QBZ-1 was observed by microscope,and the results showed that the bacteria were mainly long rod-like,and a few were short rod-like.Furthermore,the bacterium was confirmed as the gram-positive by Gram-staining.It was found that the strain QBZ-1 can produce catalase to hydrolyze hydrogen peroxide,which is an oxygen-resistant bacteria,and it can produce acid during the metabolism with the bacterial physiological and biochemical tests.Sequence alignment analysis combined with 16S rRNA showed that the strain was a kind of Bacillus cereus.3.Evaluation of the biological activity of the endophyte QBZ-1 against plant pathogenic bacteria by confrontation methodUsing the confrontation method,it was found that the endophyte QBZ-1 had an inhibitory effect on the pathogens of C.lunata,C.coccodes,F oxysporum,and P.sojae with the inhibition rates 9.63%,8.43%,23.57%and 31.90%,respectively.The endophytic QBZ-1 had significant bacteriostatic activity against P.sojae and F.oxysporum.4.Evaluation the bioactivity of the fermentation products from endophytic QBZ-1 to plant pathogy by filter paper bacteriostatic methodThe bioactivity of the endophytic qBZ-1 on plant pathogy was evaluated by filter paper bacteriostatic method.The results showed that the fermentation products of Martin culture medium had inhibitory effect on 5 fungi,and the inhibitory effect on P.sojae was the best.The fermentation products of Potato Dextrose medium,Malt Extract medium and Modified Czapek-Dox medium had inhibitory effect on 4 kinds of pathogy,and the fermentation products of Gauze's medium No.1 had inhibitory effect on 3 kinds of pathogy.Considering the yield of fermentation products and the inhibitory effect of pathogy the fermentation products of Martin culture medium are more suitable for further study.It is worthwhile to further isolate and purify the metabolites produced by the endophytic bacteria QBZ-1,and conduct in-depth research on the specific medicinal molecules inhibiting these plant pathogens to provide support for the screening of new biological pesticides.