Gold Biorecovery from Plating Waste by Magnetotactic Bacterium, Magnetospirillum magneticum AMB-1
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1169-Q03-12
Gold Biorecovery from Plating Waste by Magnetotactic Bacterium, Magnetospirillum magneticum AMB-1 Masayoshi Tanaka, Masaya Kawase, Tsuyoshi Tanaka and Tadashi Matsunaga Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan ABSTRACT Magnetotactic bacteria are a unique species of bacteria, commonly recognized by the presence of magnetic particles within them. These intracellular, nanosized magnetic particles enable the bacteria to migrate and be manipulated by magnetic force. To date, magnetotactic bacteria have been widely researched and implemented in various biotechnology based applications. In this study, as an extension to its applications, the magnetotactic bacterium, Magnetospirillum magneticum AMB-1, was applied in the microbial recovery of gold from plating waste. M. magneticum AMB-1 successfully precipitated approximately 42% and 100% of gold from growth medium containing 10 µM gold and from a mixture of plating waste/growth medium containing 0.4 µM gold, respectively. These observations and results strongly suggests that an important advancement in biorecovery of rare metals and bioremediation of toxic metals was achieved in which the application of whole cell bacteria, and direct precipitation of metals from plating waste using magnetotactic bacteria was performed for the first time. INTRODUCTION Gold is renowned as one of the most expensive metals and have received great demands in diverse areas including electronics, dentistry, decorative ceramics and medicine. Its popularity has been driven by recent advancements in its catalytic properties and has prompted the development of new recovery technologies. Biorecovery of metals using microorganisms has recently emerged as a potentially attractive and environmentally friendly alternative to conventional techniques such as reclaiming treatments. Studies on biosorption of gold by algae [1], fungi [2], yeast [3] and bacteria [4] demonstrated the potential of this approach and have been considered promising. Bacteria, in particular, have been focused due to their characteristics of high surface to volume ratio and their high growth speed. Escherichia coli and Desulfovibrio desulfuricans, for example, has been tested for the biorecovery of gold from jewellery wastes [4], while Pseudomonas putida biofilms have been studied in its application for the sorption of zinc from aqueous solutions [5]. However, although bacteria have been adapted and applied in the biorecovery of heavy metals, cell recovery has been a bottleneck, as large machines and a decrease in throughput are often necessary. Therefore, in order to overcome this problem, a highly applicable and versatile method or technology is required. Magnetotactic bacteria are known to synthesize intracellular magnetic nanoparticles that enable them to be directly manipulated by magnetic force. Such unique
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