Processing of\ua0hyperaccumulator plants to nickel products

Hyperaccumulator plants may contain valuable metals at concentrations comparable to conventional ore and can be significantly upgraded by incineration. There is an incentive to recover these metals as products in order to counterbalance the cost of disposing the contaminated biomass from contaminated soils, mine tailings, and processing wastes. Metal recovery has become an essential challenge as conventional ore grades decrease. Metal recovery is included in the agromining chain, which has been developed over the past two decades for Ni. More than 520 Ni hyperaccumulator species are currently known and some of these grow quickly providing a high-farming yield. Nickel recovery has been investigated at the laboratory scale and some processes have been upscaled. Most often, dry plants are burnt to produce ash, which has a very high Ni content, then the Ni in the ash is leached into aqueous solution. From there, the Ni is recovered by precipitation to obtain Ni salts or oxide. This hydrometallurgical route has now been scaled up. Other studies have aimed to obtain catalysts from ash or direct extraction of Ni from the plants. In the latter case, further processing requires complicated purification steps. Finally, the plants have also been treated by pyrometallurgical processes to produce Ni metal; initial studies have been carried out using pyrolysis. Interest in the production of carbon-supported Ni catalyst materials is increasing day by day, owing to the potential capacities of these products for use in bio-refineries. Finally, economic and environmental considerations are proposed here for supporting the interest of Ni recovery by agromining

Processing of bio-ore to products

Hyperaccumulator plants may contain valuable metals at concentrations comparable to those of conventional metal ore and can be significantly upgraded by incineration. There is an incentive to recover these metals as products to partially counter-balance the cost of disposing the contaminated biomass from contaminated soils, mine tailings, and processing wastes. Metal recovery is included in the agromining chain, which has been developed over the past two decades for Ni and Au. More than 450 Ni-hyperaccumulator species are currently known and some grow quickly providing a high farming yield. Nickel recovery involves an extraction step, ashing and/or leaching of the dry biomass, followed by a refining step using pyro- or hydrometallurgy. The final products are ferronickel, Ni metal, Ni salts or Ni catalysts, all being widely used in various industrial sectors and in everyday life. Gold can be recovered from mine tailings using a number of plant species, typically aided by a timed addition of an Au-chelating extractant to the soil. Dry biomass is ashed and smelted. This approach enables the treatment of resources that could not be effectively processed using conventional methods. In addition to nickel and gold, the recovery of other metals or elements (e.g. Cd, Zn, Mn, REEs) has been investigated. Further effort is required to improve process efficiency and to discover new options tailored to the unique characteristics of hyperaccumulator plant biomass

Proteomics reveals signal peptide features determining the client specificity in human TRAP-dependent ER protein import

In mammalian cells, one-third of all polypeptides are transported into or across the ER membrane via the Sec61 channel. While the Sec61 complex facilitates translocation of all polypeptides with amino-terminal signal peptides (SP) or transmembrane helices, the Sec61-auxiliary translocon-associated protein (TRAP) complex supports translocation of only a subset of precursors. To characterize determinants of TRAP substrate specificity, we here systematically identify TRAP-dependent precursors by analyzing cellular protein abundance changes upon TRAP depletion using quantitative label-free proteomics. The results are validated in independent experiments by western blotting, quantitative RT-PCR, and complementation analysis. The SPs of TRAP clients exhibit above-average glycine-plus-proline content and below-average hydrophobicity as distinguishing features. Thus, TRAP may act as SP receptor on the ER membrane’s cytosolic face, recognizing precursor polypeptides with SPs of high glycine-plus-proline content and/or low hydrophobicity, and triggering substrate-specific opening of the Sec61 channel through interactions with the ER-lumenal hinge of Sec61α