Bioleaching of Gold from Sulfidic Gold Ore Concentrate and Electronic Waste by Roseovarius tolerans and Roseovarius mucosus
MICROORGANISMS
Authors: Kudpeng, Kanjana; Bohu, Tsing; Morris, Christina; Thiravetyan, Paitip; Kaksonen, Anna H.
Abstract
Gold bioleaching mediated by iodide oxidizing bacteria (IOB) has been proposed as a sustainable alternative to conventional technologies such as cyanidation. This study evaluated the ability of two IOB sourced from a commercial culture collection, Roseovarius (R.) tolerans DSM 11457(T) and R. mucosus DSM 17069(T), to bioleach gold from electronic waste (e-waste) (1030 ppm gold) and sulfidic gold ore concentrate (45 ppm gold) using one-step, two-step and spent medium leaching at 1% pulp density over 10 days. Two-step bioleaching of ore concentrate resulted in the highest gold leaching yields (approximately similar to 100% and 34% for R. tolerans and R. mucosus, respectively), followed by spent medium leaching and one-step leaching. The yields remained low for e-waste with both strains (maximum 0.93% and 1.6% for R. tolerans and R. mucosus, respectively) and decreased over time, likely due to the instability of the solubilized gold at relatively low redox potentials (<300 mV vs. Ag/AgCl). Another limiting factor may be the partial inhibition of bacterial growth in the presence of the ore concentrate and e-waste. Therefore, future studies should evaluate the pre-treatment of the ore concentrate and e-waste to remove inhibitory and oxidant consuming compounds before bioleaching with IOB to optimize leaching yields.
Species of the Maera-clade collected from Japan. Part 4: addenda to genera Maera Leach, 1814 and Quadrimaera Krapp-Schickel & Ruffo, 2000, with revised keys to Japanese species of the Glade (Crustacea: Amphipoda: Maeridae)
ZOOTAXA
Authors: Ariyama, Hiroyuki; Kodama, Masafumi; Tomikawa, Ko
Abstract
Two new species of Maera Leach, 1814 and Quadrimaera Krapp-Schickel & Ruffo, 2000 included in the Maera-clade are described from Japan. Maera denticoxa sp. nov. was collected from Iwate and Hokkaido Prefectures and can be distinguished from its congeners by the small notches on the posteroventral margins of coxae 1-6. Quadrimaera angulata sp. nov. from north of Tanegashima Island in Kagoshima Prefecture is characterized by the distal tooth on the mandibular palp article 1, the rounded palm of the female gnathopod 2, and the angular posterodistal margin of the pereopod 7 basis. Keys to Japanese species of the Maera-clade are provided. In total, seventeen species included in the Glade occur in Japan.
COA
Publication 
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