Biosorption mechanism of Cr （Ⅳ） onto cells of Synechococcus sp.

The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetics study shows that the adsorption process of Cr （Ⅳ） consists of a very fast stage in the first several minutes, in which more than half of the saturation adsorption is attained, and a slower stage that approximately follows the first order kinetic model, basically Freundlich isotherm models were observed. Comparative studies of FT-LR spectra of K2Cr2O7, free cells of Synechococcus sp., and Cr-bound cells of Synechococcus sp show that the speciation of chromium that binds to the cells ofSynechococcus sp. is Cr （Ⅲ）, instead of Cr （Ⅳ）, and the carboxylic, alcoholic, amido and amino groups may be involved in the binding of Cr （Ⅲ）. Integrative analyses of the surface electric potential, the effect of pH value on adsorption behavior of Cr （Ⅵ）, and the results of FT-IR show that the biosorption of Cr （Ⅵ） follows two subsequent steps, biosorption of Cr2O7 ^2- by electrostatical force at the protonated active sites and reduction of Cr2O7^2- to Cr^3＋ by the reductive groups on the surface of the biosorbents.     

绿色化学和矿物资源高效利用

前瞻了绿色化学与矿物资源高效利用之间的关系, 对传统矿物加工过程的特征和绿色化学应用的重要性、环境友好的选冶方法(包括生物浸出、非氰化浸出金和矿山污染源的微生物转化等)的研究和应用以及如何发展绿色化学和技术进行了探讨, 提出了促进我国矿物资源高效利用的初步构想。     

Sulfur activation-related extracellular proteins of Acidithiobacillus ferrooxidans

The fractions of the extracellular proteins of Acidithiobacillus ferrooxidans grown on two different energy substrates, elemental sulfur and ferrous sulfate,were selectively prepared with hot water treatment and distinctly shown by two-dimensional gel electrophoresis.Some protein spots with apparently higher abundance in sulfur energy substrate than in ferrous sulfate energy substrate were identified by using MALDI-TOF/TOE Based on peptide mass fingerprints and bioinformatical analysis,the extracellular ...     

Comparative study on effects of Tween-80 and sodium isobutyl-xanthate on growth and sulfur-oxidizing activities of Acidithiobacillus albertensis BY-05

Effects of two typical surfactants, Tween-80 and sodium isobutyl-xanthate （NaIBX）, with different concentrations on the growth and sulfur-oxidizing activities of a new strain Acidithiobacillus albertensis BY-05, an acidophilic sulfur-oxidizing bacterium, were investigated. The results indicate that both surfactants can enhance the growth and sulfur-oxidizing activities of A. albertensis BY-05 only at some special concentrations, e.g., 10^-4-10^-8 g/L for NaIBX and lower than 10^-8 g/L for Tween-80, but were inhibited and even harmful at higher concentrations. Both surfactants can not be metabolized by A. albertensis BY-05. The contact between the bacteria and the sulfur particles may be dependent upon both the extracellular substance and the surfactants, both of which provide the amphiphilic environment improving the attachment for bacteria to the sulfur particles surface. These data could be significant for enlarging the applications of both A. albertensis BY-05 and some typical surfactants for industrial bioleaching of sulfides minerals.     

不同材料固定化柚苷酶的比较

选取壳聚糖、海藻酸钠、活性炭和氧化石墨烯对柚苷酶进行固定化,比较不同材料对柚苷酶的载酶率和固定化酶活,得到较佳的固定化材料为氧化石墨烯,其载酶率达85.61%,酶活达410.50 U/g,重复使用7次后仍能保持72.38%的相对酶活。同时研究了不同条件对氧化石墨烯固定化柚苷酶催化活性影响,得到较佳的固定条件:载酶量为每克氧化石墨烯材料承载60 mg柚苷酶,固定化温度为20℃,p H值为4.0,固定化吸附时间为9 h,优化后氧化石墨烯固定化柚苷酶的酶活为433.70 U/g,重复使用7次后仍保留78.62%的酶活。     

广东梅州浸矿细菌的选育及对金属硫化矿的浸出

从中国南方典型矿区——广东梅州玉水生物提铜示范基地酸性矿水中分离得到一株金属硫化矿浸出微生物YS-1.对菌株YS-1的形态、生理生化特征、16S rDNA种系序列以及对黄铁矿和铁闪锌矿的浸出等进行了研究.结果表明：细菌长1.0～2.5μm,直径0.4～0.6μm,能运动,革兰氏染色显阴性,最适宜生长的pH和温度分别为2.0和30℃,能利用亚铁盐、单质硫和硫代硫酸钠,不能利用有机能源,与嗜酸氧化亚铁硫杆菌的16S rDNA种系序列同源性达到98%,对铁闪锌矿和黄铁矿的浸出率分别为14.38%和3.8%.     

3种典型能量代谢菌浸出黄铜矿及其硫形态的转化

比较了3种典型嗜中温铁/硫代谢菌——Acidithiobacillus ferrooxidans、Leptospirillum ferriphilum及Acidithiobacillus thiooxidans单独及混合浸出黄铜矿过程中细菌硫氧化、铁氧化情况。同时利用XRD、硫的K边X射线吸收近边结构光谱(XANES)等分析手段研究3种细菌单独/混合浸出黄铜矿过程中矿物组成成分和矿物表面硫的形态变化。结果表明:在浸出初期电位低于400 mV(vs SCE)时,黄铜矿的浸出速率较快,此后电位迅速升高至540 mV,黄铜矿浸出速率明显变慢。混合菌浸出时体系的硫/铁氧化活性较单一菌高,根据XANES拟合分析发现,混合菌浸出时矿物表面元素硫及黄钾铁矾积累量明显减少,浸出初期辉铜矿产量明显高于单一细菌浸出的。     

极大螺旋微藻(分节螺旋属)在一六面体光合生物反应器中生物合成13C标识氨基酸和糖

This paper presents the investigation on biosynthesis of high-value-added amino acids and sugars labeled uniformly with stable isotope ^13C by microalga Spirulina (Arthrospira) maxima in a parallelepiped photobioreactor.The kinetic data of both batch and continuous cultures with characterization of the amino acids and sugars are shown. The continuous culture without nutrients deficiency is for biosynthesis of amino acids, with tyrosine as one of the principal constituents, and the batch culture with deficiency in nitrogen is for biosynthesis of labeled glucose that is uv to 64% versus dry mass of cells.     

Extraction and characterization of PHB from <Emphasis Type="Italic">Acidiphilium cryptum</Emphasis> DX1-1

A new bacterial strain, was designated as strain Acidiphilium cryptum DX1-1, accumulates intracellular poly-β-hydroxybutyrate particles, four methods which have advantages and disadvantages for each were employed to extract PHB. Chloroform-sodium hypochlorite method is the best in extracting PHB form Acidiphilium cryptum DX1-1. The extraction rate reaches 73%, the purification rate is 92% and molecular weight is 326 kg/mol. Then the PHB extracted by this method was analyzed by ultraviolet-visible absorption spectroscopy, fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR). The results show that PHB from strain DX1-1 has the same biochemical structure and character with PHB standard. Mass spectrometer (MS) analysis reveals that the long chain of PHB is destroyed when treated by chloroform-sodium hypochlorite. The differential scanning calorimetry (DSC) of PHB shows PHB from Acidiphilium cryptum DX1-1 has low degree of crystallinity which makes the PHB has a wider range of applications.