Development and Application of an Assay for Uranyl Complexation by Fungal Metabolites, Including Siderophores

Abstract

An assay to detect UO 2 2؉ complexation was developed based on the chrome azurol S (CAS) assay for siderophores (B. Schwyn and J. B. Neilands, Anal. Biochem. 160:47-56, 1987) and was used to investigate the ability of fungal metabolites to complex actinides. In this assay the discoloration of two dyed agars (one containing a CAS-Fe 3؉ dye and the other containing a CAS-UO 2 2؉ dye) caused by ligands was quantified. The assay was tested by using the siderophore desferrioxamine B (DFO), and the results showed that there was a regular, reproducible relationship between discoloration and the amount of siderophore added. The ratio of the discoloration on the CAS-UO 2 2؉ agar to the discoloration on the CAS-Fe 3؉ agar was independent of the amount of siderophore added. A total of 113 fungi and yeasts were isolated from three soil samples taken from the Peak District National Park. The fungi were screened for the production of UO 2 2؉ chelators by using the CAS-based assay and were also tested specifically for hydroxamate siderophore production by using the hydroxamate siderophore auxotroph Aureobacterium flavescens JG-9. This organism is highly sensitive to the presence of hydroxamate siderophores. However, the CAS-based assay was found to be less sensitive than the A. flavescens JG-9 assay. No significant difference between the results for each site for the two tests was found. Three isolates were selected for further study and were identified as two Pencillium species and a Mucor species. Our results show that the new assay can be effectively used to screen fungi for the production of UO 2 2؉ chelating ligands. We suggest that hydroxamate siderophores can be produced by mucoraceous fungi.

Production and Characterization of Siderophores and its Application in Arsenic Removal from Contaminated Soil

“…Aiken et al (2003) reported that siderophore bind divalent metals like Cd 2+ , Ni 2+ , Zn 2+ , Cu 2+ , Co 2+ , Sn 2+ , Pb 2+ with varying capacities. A similar test for uranyl complexation was reported by Renshaw et al (2003). This is an indicative test.…”

Genotypic diversity among rhizospheric bacteria of three legumes assessed by cultivation-dependent and cultivation-independent techniques

“…Soil enzymatic patterns pH, urease activity, alkaline phosphatase activity and enzymatic patterns of rhizospheres were analyzed. pH of rhizosphere soil sample was measured as described by Renshaw et al (2003). Urease activity was measured as described by Askin and Kizilkaya (2006), except that the soil suspension was not diluted with distilled water and 5 ml of the soil filtrate was used to make a reaction mixture.…”

Modified chrome azurol S method for detection and estimation of siderophores having affinity for metal ions other than iron

“…Methanotrophs produce siderophore referred as chalkophore (Yoon et al 2010), that has high affinity for copper ions. Aiken et al (2003) and Nair et al (2007) Renshaw et al (2003). Sayyed et al (2015) have reported efficient good growth, siderophore of exopolysaccharide producing Enterobacter sp RZS5 in presence of various heavy metal ions.…”