Abstract:

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 on Alternaria 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 inthe single factor test with sucrose, peptone5 g/L, temperature34 ℃, 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 (sucrose6 g/L, peptone5 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.

Key words:

Panax ginseng, siderophore, bacteria, biocontrol