Cloning and sequencing of the fur gene from marine probiotic alteromo nas aurantia a18 and its possible role in siderophore production

Abstract

The complete fur gene from the marine probiotic Alteromonas aurantia A18 was amplified by PCR and the cloned gene was sequenced. Results indicated that the similarity between the sequence of the fur gene from strain A18 and that from Alteromonas sp O-7 was 97%. Fur protein of strain A18 was 98% identical to that of Alteromonas sp. O-7 and 70% identical to that of E. coli. The putative fur open read ing frame coded for 148 amino acids representing a protein of 16.637 kDa. The recombinant expression vector pQE30-fur was constructed to confirm function of the cloned fur gene in E. coli. We found that siderophore yields of the transformants bearing pQE30-fur (induced by IPTG) were much lower than those of the parental strain and the same transformants that were not induced by IPTG in the iron-rich medium. The results suggest that some enzymes responsible for biosynthesis and secretion of sideropho res in E. coli were repressed by the Fur protein encoded by the fur gene from A. aurantia A18.