ABSTRACT
To enhance the crop production and to manage plant diseases, many chemicals are being used. The use of such agrochemicals is hazardous to environment. To identify a viable alternate, biocontrol agent is necessary. Keeping this in point, the present investigation was undertaken to isolate PGPR bacteria from paddy rhizospheric soil. A total of 100 bacteria were isolated. On the basis of morphological, physiological and biochemical characterisation most of the isolates belong to Pseudomonas aeruginosa. The isolates were further screened for siderophores production by CAS method. In this 10 isolates showed positive results in siderophore production. The produced siderophore were further characterised based on their classi?cation such as hydroxylate, catecholate and carboxamate depending on the iron ligating group. In the present study, the effect of culture media components in the yield of siderophore was studied. Among the 10 isolates, 3 of were produced catecholate type of siderophore ef?ciently in succinate medium at neutral pH in low iron concentration. Potential siderophore producing isolates was further applied on Vigna radiata (Green gram). There was a signi?cant increase in the shoot and root length by roll towel method and Pot assay method
ABSTRACT
Siderophores are low molecular weight iron chelating secondary metabolites synthesized by various groupsof microorganisms help in scavenging iron-limited conditions. Siderophores produced by endophytic bacteriafacilitate the plant growth by providing iron to plants. The objective of this study was to isolate and screenthe siderophore producing endophytes from nodules and roots of Cicer arietinum and Pisum sativum plants.Out of total 84 isolates, only 14 endophytes produced siderophore and quantitative analysis was also done.Ten best siderophore producers (above 65% siderophore units) were characterized for the type of siderophoreproduced. Most of them were producing hydroxamate and carboxylate type of siderophores. These 10 isolateswere evaluated for other plant growth promoting (PGP) traits in vitro. All of them were producing ammoniaand indole-3-acetic acid (IAA). Isolate CPFR10 was found to be positive for all the PGP traits viz. ammonia,organic acid, HCN, and IAA production. Diversity analysis of these 10 isolates using Amplified rDNARestriction Analysis profile revealed nine genotypes at 90% similarity
ABSTRACT
A novel stable blue agar plate which is convenient to preparing and more effective than the universal chrome azurol sulfonate (CAS) assay established by Schwyn and Neilands was designed by replacing MM9 growth medium and pipes with certain concentrate of phosphorus buffer solution which pH could be stabled at 6.8. It is more suitable for screening over- siderophores production bacteria. Since OD_ 630 of the sample is usually out of the range of spectrophotometer with CAS assay solution when quantifying the siderophores and the outcome is not steady,the measuring wavelength had been changed to 680 nm corresponding to the middle of max absorbance and the correlation between siderophores concentrations and OD was unchanged. But the detecting sensitivity is elevated by enlarged the absorbance differences among samples with different productivity of siderophores at 680 nm .
ABSTRACT
CAS (Chrome azurol S) assay was a universal method for detecting the bacterial siderophores, and Sugar-Asn liquid medium has been applied to the studies on siderophores from Pieudomonas. In this paper, Asp has been substituted for Asn, and MSA-CAS agar plate was developed by integrating the MSA (sugar-Asp) medium and CAS bright blue dye, which has been used in the universal CAS assay. On the aspect of siderophores detection , 8 strains of 7 species from Pseudomonas had been screened on MSA-CAS agar plates and universal CAS assay respectively. The results showed that MSA-CAS agar was higher-sensitive and lower basic fluorescent than universal CAS assay.