Screening and Identification of Siderophore-Producing Biocontrol Bacteria GR-39 from Panax ginseng andOptimization of Its Fermentation Condition
Siderophore-producing bacteria have a good biocontrol effect through competing iron with pathological bacteria.In this study,we isolated bacteria from Panax ginseng root tissue and rhizosphere soil,screened the bacteriostasis and siderophore-producing capabilities,and optimized the single factor and response surface of fermentation conditions for one selected strain.The results showed that a total of 207 strains had been isolated,including 8 strains that have both siderophore-producing capability and good inhibition effect onAlternaria panax Whetz,Fusarium solani(Mart.)App.et Wollenw.,and Cylindrocarpon destructans(Zinns.)Scholten;it was found that strain GR-39 had a significantly different bacteriostasis on A.panax Whetz in both iron-limited and iron-rich culture media,and this strain was characterized as Serratia plymuthica.The relative content of sderophore was determined to be 74.6％for strain GR-39 in the single factor test with sucrose,peptone 5 g/L,temperature 34 ℃,and pH 8;The regression model of siderophore content and independent variable was established through response surface method,the maximum yield of siderophores in the optimal fermentation condition(sucrose 6 g/L,peptone 5 g/L,and pH 8)was 77.13％.The present study suggested that GR-39 has a strong siderophore-producing capability and a significant biocontrol effect on A.panax Whetz,thus can provide good strain resources as a multifunctional microbial agent.
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