Preliminary Study On Fermentation Condition And Application Of Pyoverdine

One hundred and four Pseudomonas fluorescens strains from Qingpu, Songjiang, Fengxian, Nanhui, Pudong and Jiading districts of Shanghai were detected by CAS agar plates and CAS solution. The concentration of PVD of all strains were compared and SE-6 strain with the highest PVD excretion was screened as its relative concentration of PVD was 0.654. Under the condition of shaking flask fermentation,the potential ability of PVD produced by SE-6 was studied at different compositions of culture media and technological conditions.Single factor experiments and orthogonal experiment showed that the optimum composition for the fermentation medium(lL) was: Glycerol 1.5g, Cascamino acid 1.0g, MgSO₄.7H₂O 2.5g, K₂PO₄.3H₂O 2.5g. The optimum fermentaion conditions were: temperatrue 28℃, original pH6.5, inoculation amount 2%, media amount 200mL/500mL, culture time about 46h, the concentration of Fe³⁺0.8mg/L. Under the above conditions, the concentration of PVD is the highest.Culture media was isolated and purified.Culture media were centrifuged to remove bacteria.the supernatant extracted with organic reagents, then isolated by column chromatography with Sephadex G-25. So the extraction of PVD was available.The main functional group of PVD were sudied by fourier transform infrared spectrum(ft-ir). The type of siderophores were tested with Arnow's assay and Atkin's assay.The former was for the detection of catechol-type siderophores and the later for hydroxamate-type siderophores.The results showed PVD is a kind of mixed siderophore containing both catechol and hydroxamate group.The absobance of PVD at special wavelength could changed when it bound Fe³⁺,which can be used to design a determination way for Fe³⁺ in aqueous envirorhent.A working curve between the change of absorbance of PVD and the Fe³⁺ concentration was established,it followed Beer's law when Fe³⁺ concentration was in the range 0 to 2.25 × 10-6mol.L^-1. the linear regression equation was: y=-0.00014+0.111238x. Fe³⁺ concentration in samples could be detected with the equation, and the accuracy and precision of the determination way were assessed.Thus, it was practicable in determination of Fe³⁺ concentration and useful to realize and control red tide in ocean.