INNOVATIVE ECO-EFFICIENT BIOHYDROMETALLURGICAL PROCESSES FOR THE RECOVERY OF STRATEGIC AND RARE METALS FROM PRIMARY AND SECONDARY RESOURCES

The conventional pyrometallurgical route for winning of metals is increasingly confronted with a number of challenges which include the necessity to exploit more complex and deeper deposits, arsenic containing deposits, increased demands to protect the environment, and to use less energy. Biohydrometallurgical processes have been shown to be a good alternative for the winning of metals from poor and complex ores

pShuffle: A Plasmid for in vitro Evolution

Multi-gene shuffling is a powerful method used to combine and optimize attributes of various proteins. Here we report on the design and construction of the plasmid “pShuffle” which is suited for a variety of in vitro DNA-recombination techniques. The multiple cloning site (MCS) of pShuffle was designed to allow for the cloning of genes as well as their expression under control of either a lac- or a T7-promoter. As a specific feature, this MCS allows for the fusion of special linker sequences to both ends of cloned genes. After subsequent DNA-recombination steps, these linkers facilitate reamplification of generated gene variants, and thus may be used to construct clone libraries for activity screenings. The suitability of pShuffle for multi-gene shuffling applications was further shown with a set of styrene monooxygenase genes originating from proteo- and actinobacteria

Crystal Structure of the Hydroxyquinol 1,2-Dioxygenase from Nocardioides simplex 3E, a Key Enzyme Involved in Polychlorinated Aromatics Biodegradation

Hydroxyquinol 1,2-dioxygenase (1,2-HQD) catalyzes the ring cleavage of hydroxyquinol (1,2,4-trihydroxybenzene), a central intermediate in the degradation of aromatic compounds including a variety of particularly recalcitrant polychloro- and nitroaromatic pollutants. We report here the primary sequence determination and the analysis of the crystal structure of the 1,2-HQD from Nocardioides simplex 3E solved at 1.75 A resolution using the multiple wavelength anomalous dispersion of the two catalytic irons (1 Fe/293 amino acids). The catalytic Fe(III) coordination polyhedron composed by the side chains of Tyr164, Tyr197, His221, and His223 resembles that of the other known intradiol-cleaving dioxygenases, but several of the tertiary structure features are notably different. One of the most distinctive characteristics of the present structure is the extensive openings and consequent exposure to solvent of the upper part of the catalytic cavity arranged to favor the binding of hydroxyquinols but not catechols. A co-crystallized benzoate-like molecule is also found bound to the metal center forming a distinctive hydrogen bond network as observed previously also in 4-chlorocatechol 1,2-dioxygenase from Rhodococcus opacus 1CP. This is the first structure of an intradiol dioxygenase specialized in hydroxyquinol ring cleavage to be investigated in detail

Degradation of haloaromatic compounds

An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level