Analysis Of The Biosynthesis Conditions And Characteristics Of Siderophores From Pseudomonas Sp. SPF-1

In this study, universal CAS assay was used to screen basic characteristic of Pseudomonas sp. SPF-1 which was isolated from the East-lake of Wuhan. The siderophroe of Pseudomonas sp. SPF-1 was analysed by mensurating the ratio of the diameter of the siderophore and the colony, running wave scanning under ultraviolation to visible light and determining the optical density at 600 nm, 400 nm and the changing of the optical density at 630 nm after the siderophore combined with Fe3+. The siderophore was purified by Sephadex G-25, and the characteristic of which was determined.The biosynthesis condition of siderophore from Pseudomonas sp. SPF-1 was compared with other 7 species of Pseudomonas. And the results showed as the followings.The optimal conditions of producing siderophores were the temperature at 28-30 °C, the pH value at 7.5-8.0 andunder better condition of aeration. Found the difference of siderophore yield between these 8 strains of Pseudomonas, and secreted two kinds of siderophroes which were fluorescent and non-fluorescent. Compared thedifference responsion to iron between these two kinds of siderophroes, the result showed that the fluorescent siderophore was more sensitive than non-fluorescent siderophore.When the concentration of iron was exceeded to 1μM on which the growth was promoted and the yield of siderophroe of Pseudomonas sp. SPF-1 was inhibited seriously, which was more obviously on agar plate than in liquid medium. However 2-4 uM of iron chelators could accelerate the secretion of siderophores, whereas the chelators of calcium and magnesium did not. And we also found that the MSA medium was moreyared and suitable to detect fluorescent siderophores from Pseudomonas.The fluorescent siderophore was purified by using the resin of Sephdex-G25 and the basic chartersitics of fluorescent siderophore was determined. The results showed that the fluorescent siderophore a water soluble organism with a high temperature stability and proper absorbance at 400 nm. The maximal absorbance changed went with pH value. The fluorescence was disappeared but the optimal optical density at 400 nm was also existed when fluorescent siderophore combined with iron. The purified siderophore could producd halo on universal CAS agar which was the same to Pseudomonas sp. SPF-1. Three groups of fluorescent siderophores were detected by electrophoresis and thin-layer chromatogram. There were much moredifference of these three groups of these three groups of fluorescent on polarity. We had compared with fluorescent siderophoreand flurescein, and the results showed that there were difference betweenthem on the aspects of spectrum absorbance and transportation of iron(III).The results of this study showed that the MSA-CAS detection agar which we constructed in this study, was a high-sensitive detection method on siderophres, especially for fluorescent siderophore. And we found the different response to iron(III) between fluorescent and non-fluorescent siderophores. Which would proceed the research of siderophores from Pseudomonas sp. SPF-1.