Bacteria leach metals from ocean nodules.

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“Bacteria have been used to extract other metals from ore, in a process called bio-leaching. But these would not work on the nodules. Instead the researchers isolated a species of Bacillus from the nodules themselves. When they fed them crushed nodules in a growth medium, the bacteria dissolved up to 45 per cent of the metals within four hours by breaking up the oxide complexes. ‘This is the first time anyone has used marine bacteria for bio-leaching,’ says Ashok Raichur, a researcher on the project.

“To their surprise, the team found the process still worked when all bacterial cells were removed. In other bio-leaching, it is the cell membrane of the living organisms that breaks up the oxides. But with marine bacteria the work is done by complex organic products that they deposit.” (Dicks 2004:23)

Journal article
Marine bugs have a flair for deep-sea mining.Lynn Dicks

“For decades, mining companies eyed with interest the fist-sized lumps of mineral littering the floor of the world’s deep oceans. Made largely of manganese dioxide and other oxides, these mysterious nodules harbour valuable metals like copper, nickel and cobalt.

“The cost of mining on the seabed at least 4 kilometres down makes the prospect unattractive to most companies, but a bacterium that inhabits the nodules in the Indian Ocean could improve the economics of deep-sea mining by making extraction cheaper. Scientists from the Indian Institute of Science in Bangalore have used the bacterium to extract metals from the nodules at room temperature (Journal of Chemical Technology and Biotechnology, vol 79, p 512).

Journal article
Exploring process options to enhance metal dissolution in bioleaching of Indian Ocean nodulesJournal of Chemical Technology and BiotechnologyApril 6, 2004
Amitava Mukherjee Ashok M Raichur Jayant M Modak KA Natarajan

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