Preliminary Study On The Trap Formation Induced By Bacteria In Arthrobotrys Oligospora

Diseases caused by plant-parasitic nematodes have always been the main diseases in agricultural production,causing serious losses to many important crops.As the drawbacks of chemical control continue to emerge,searching biological control resources is gaining more and more attention.Nematode-trapping fungus,the natural enemy of nematodes,is the main choice for biological control of plant-parasitic nematodes.The trap device is the main weapon for nematode-trapping fungus.The trap's formation and number play a decisive role in its defense against nematodes.Therefore,it is crucial to explore the factors that can promote the formation of traps for nematode-trapping fungus.In recent years,many studies have shown that bacteria and their metabolites play an important role in trap formation.In the soil,bacteria-fungi-nematodes share a microenvironment,and many mechanisms have evolved to coordinate and control each other to maintain ecological balance.In this paper,98 strains of bacteria were identified by 16 SrDNA.They belong to Pseudomonas?Pseudochrobactrum?Brevibacterium?Microbacterium?Ochrobactrum?Plantibacter?Cronobacter?Delftiasp?Enterobacter?Herbiconiux?Sphingobacterium?Acinetobacter?Bacillus and Escherichia.At the same time,their activities of inducing the trap formation of Arthrobotrys oligospora were screened and 33 strains of bacteria showed inducing activity.Among the active strains,7 strains of Pseudomonas lurida have strong activity.This is the first report that this bacterium has the activity of inducing trap formation.Strain Pseudomonas lurida C38 was proved to have broad-spectrum inducing activity.The fermentation products can induce the formation of adhesive net,adhesive knob,adhesive branch and constricting rings.LB medium was selected for fermentation the strain.Ten compounds were isolated from the ethyl acetate and n-butanol extracts,and 7 compounds were identified: nicotinic acid(mb-1),cyclo-L-Tyr-L-Pro(mb-3),3-phenylpropanoic acid(ma-10),4-hydroxy-benzeneacetic acid-methyl ester(mw-1),4-hydroxy-benzeneacetic acid(ma-13),L-tryptophan(ma-3),and 2-amino-naphthalene(ma-18),L-tryptophan showed induced activity.The main volatile metabolites produced by P.lurida were identified by GC-MS.They were 3,5-bis(1,1-dimethylethyl)-phenol ? cyclotetradecane ? 1-octadecanol ?1-nonadecene?11-hexadecenoic acid methyl ester?hexadecanoic acid methyl ester?14-methyl-,pentadecanoic acid methyl ester?dibutylphthalate?N-hexadecanoicacid?3-benzylpyrrolopiperazine-1,4-dione ? dihydro-5-(hydroxymethyl)-2(3H)-furanone ?eicosane ? 1-decene ? cyclopropane,nonyl-? 1-tetradecanol ? decane,5,6-dipropyl-?E-14-Hexadecenal ? 1-hexadecene ? 1-hexadecanol ? Z-7-hexadecenoic acid ? S,S-dioxide 4-n-hexylthiane?(9E,12E)-octadecadienoic acid methyl ester?9-octadecenoic acid methyl ester?13-octadecenoic acid methyl ester?octadec-9-enoic acid?1,9-tetradecadiene?octacosane and tricosane?(9Z)-hexadecenoic acid methyl ester.Their activities of inducing the trap formation of Nematode-trapping fungus need further screened.