Gene function and microbial community structure in sulfide minerals bioleaching system based on microarray analysis / 生物工程学报

Biohydrometallergy technology received more and more attention because of its simple process, low cost and kind to environment, especially in dealing with low-grade and complex minerals. However, it is difficult to optimize microorganism species and process parameters in bioleaching procedure because of the lack of suitable bacteria and quantitative analysis methods at micro-level for bioleaching system. This has resulted in the low efficiency and poor yield of the target metal in bioleaching. With the development of microarray and bacteria conservation technology, solutions to the above problems were being found. This article summarizes the latest findings on genetic elucidation and the community structure of microorganisms in sulfide minerals bioleaching system, in the aim of providing a better understanding on the significance of cross-field technology of biohydrometallergy and genomics.

Optimization of culture condition of a moderately thermophilic acidophilic Ferroplasma thermophilum / 生物工程学报

The extreme microorganisms Ferroplasma spp., play an important role in bioleaching of sulphide ores at low pH value and temperatures around 50 degrees C. Without cell wall, Ferroplasma spp. is sensitive to pulp density, shearing force and heavy metal ions. Thus it is difficult to obtain their high cell density cultures, which limits the large-scale industrial application. In this paper, the optimum culture conditions of Ferroplasma thermophilum were studied by shaking culture. The results showed that the optimum culture conditions are as follows: 50 degrees C, initial pH 0.5, 50 mL working volume in 250 mL shaking-flask, inorganic nitrogen source (NH4)2SO4. The optimum combination of FeSO4.7H2O, yeast extract and peptone was determined by orthogonal experiments, including FeSO4.7H2O 40 g/L, yeast extract 0.3 g/L, peptone 0.2 g/L. Under the optimum culture conditions, the cell density was up to 6.3 x 10(7) cell/mL, and the oxidation of 40 g/L ferrous sulfate heptahydrate was finished in less than 72 hours. The results might provide information for scale-up of archaeon culture as well as its industrial application.

Structure Modeling and Evolutionary Trace Analysis of Superoxide Dismutase from Extremophile Thermoplasma Acidophilum / 现代生物医学进展

To investigate the superoxide dismutase in extremthermoacidal environment,a reliable three-dimensional molecular structure of the protein encoded by the sod gene from Thermoplasma acidophilum was built.Evolutionary trace analysis of this protein detected 11 trace residues.Among them,the residues of Ash39,Gly105 and Glu162 were randomly scattered throughout the mapped structure;the other residues were all distinctly clusteredin a subgroup near Fe atom binding site.From these results,this gene encoded a Fe-depending superoxide dismutase based on the modeled structure;moreover,the detected trace residues around Fe atom might be directly responsible for Febinding and catalytic function.

Extraction of Magnetosome from Acidthiobacillus ferrooxidans / 现代生物医学进展

In physiological property and growing environment aspects, there are some similarities between Acidthiobacillus ferrooxidans(ATF) and magnetotactic bacteria. ATF shows magnetotacxis under the microscope. The magnetosome can be extracted from ATF by using the extracting method of magnetosome from magnetotactic bacteria. The membrane of ATF was crushed by ultrasonic wave and the magnetosomes in the ATF which mainly contains Fe through chemical detection were attracted by using magnetite. After purifing with sucrose density gradient centrifugation and washing by PBS, the magnetosomes can be seen clearly through a transmission electron microscope. The results indicate there are a small amount of intracellular magnetosomes which made the ATF be magnetotactic under the applied magnetic field. It is the first time to find that ATF was magnetotactic. The magnetotaxis of ATF can be utilized and isolated by the magnetotactic properties to gain the high-performance ATF strains of mineral leaching, which have high activity and different magnetism.