VERSATILE FLUORESCENT PIGMENTS FROM AN ANTARCTIC BACTERIUM: CHARACTERIZATION AND ENVIRONMENTAL APPLICATION

Siderophores are important secondary microbial metabolites that chelate iron and, in recent years, the study of their application in the environmental remediation of metals has been intensified, due to the strong affinity, towards metals other than iron [1]. These research, may in the future, provide a viable, economically, and ecologically advantageous alternative to the more dangerous and invasive remediation methods involving the use of synthetic chemicals. Pyoverdine is a siderophore, characterized by a specific fluorescent dihydroxyquinoline chromophore, and different dicarboxylic-side and peptide chain, bounded to the amino group and to the carboxyl group of the chromophore, respectively, that are specific for each bacterial species [2]. More than 100 pyoverdines have been identified from different bacteria; although these are structurally different, they nevertheless share common features [3]. Until now, few studies have been characterized these pigments and elucidate their peculiar properties. In this study, a mix of Pyoverdines (PYs), produced by Marinomonas sp. Ef1, a bacterium isolated from a consortium associated with the Antarctic ciliate Euplotes Focardii, was purified, and chemically analysed. The biosynthesized PYs are pale yellow, water-soluble and fluorescent. After purification, spectrophotometric and fluorometric characterization were carried out. HPLC analysis performed by using DAD, FLD and MS detectors, demonstrated that the sample was composed by a mix of seven pyoverdines and the relative masses were obtained. The complexing ability for different metal ions was also investigated by spectrophotometric and fluorometric measurements. The obtained results showed that different metal ions are complexed from PYs, while Cr(VI), that in the studied pH conditions was present as CrO4 2- , is reduced to Cr(III) and successively complexed. This important result offers the possibility to use this pyoverdines mix in the control of Cr(VI) pollution.