Fe(III) reduction by halomonas sp. TBZ9 and maribobacter sp. TBZ23, isolated from urmia lake in Iran.

Iron is an important abundant element in the environment, which its mobility and stability is partly under the control of oxidation state. Microbial iron reduction plays an important role in the iron cycle and affects the exchange of nutrients and trace elements in ecosystems. Dissimilatory reduction of ferric iron oxides plays an important role in mineralization of organic materials in anoxic soils and sediments and also makes up an important fraction of anaerobic carbon metabolism in special marine and freshwater environments. Some bacteria and archaea can grow anaerobically using Fe(III) as the sole electron acceptor and some fungi also are able to reduce Fe(III) to Fe(II). In this study, iron reduction was investigated using bacterial isolates TBZ9 and TBZ23, isolated from Urmia Lake in Iran. Differential pulse polarography was exploited to measure different reduced forms of iron in control and treated samples. The results showed that both isolates are able to reduce Fe(III) to Fe(II) and Fe(II) to metallic Fe. Based on intensity of differential pulse polarogram peaks observed respectively at - 0.34V and -0.51 V, it seems that TBZ23 reduces almost 14.11% of available Fe(III) to Fe(II) and this reduction rate is about 72.12% for TBZ9 during 10 days of incubation. The rate of reducing Fe(II) to metallic Fe is seemingly 21.14% for TBZ23 and 64.79% for TBZ9 during 10 days of incubation. Therefore, isolate TBZ9 is an environmental bacterium with higher potential to reduce ferric iron to ferrous iron and also to reduce ferrous iron to metallic iron. Consequently, this isolate can play an important role in environmental cycling of iron, carbon, and other elements.