A new strain Leptospirillum ferriphilum YTW315 for bioleaching of metal sulfides ores

A new strain named YTW315 was isolated from Dexing area using the double-layer culture technique. The morphological, biochemical and physiological characteristics of YTW315 were studied. Physiological investigation indicates that the strain YTW315 is a strict (obligate) chemolithoautotroph, metabolizing ferrous iron and pyrite. The optimal growth conditions for the strain are 40 ℃ and pH 1.6. A phylogenetic analysis based on 16S rRNA sequences shows that the isolate is clustered to Leptospirillum ferriphilum with 99.8% similarity to Leptospirillum ferriphilum strain Fairview and ATCC 49881. The molar fraction of DNA (G+C) of the isolate is 58.1%. The strain can tolerate high concentration of Fe(Ⅲ) and As(V) (500 mmol/L and 50 mmol/L, respectively). Bioleaching experiment indicates that the strain can oxidize Fe(Ⅱ) efficiently, and after 30 d, 44.56% of copper and 95.31% of iron are extracted from chalcopyrite and pyrite, respectively.     

Identification and fermentation optimization of protopectinase-overproducing strain Aspergillus niger CD-01 for pectin production

In order to solve the citrus peel resource waste problem and minimize the drawbacks of chemical extraction of pectin, a protopectinase-overproducing strain CD-01 for pectin production was isolated from a pit soil dumped with perished orange in Changde City, Hunan Province of China. The strain CD-01 had the same morphology and 28S rRNA gene sequence (FJ184995) as that of Aspergillus niger (ATCC 64028). It was thus identified and named as Aspergillus niger CD-01. The fermentation condition was optimized based on L₉(3⁴) orthogonal experimental design and the variances analyses. The results show that the optimal condition for producing pectin is as follows: time 36 h, temperature 35 °C, pH 5, and urea as the nitrogen source. Under this condition, the pectin yield can reach up to 24.5%. This shows a great potential of Aspergillus niger CD-01 in pectin extraction from citrus. Foundation item: Projects(50621063, 50674101) supported by the National Natural Science Foundation of China     

Purification and characterization of extracellular chitinase from a novel strain Aspergillus fumigatus CS-01

Twelve samples derived from different locations in south central area of China are treated by enrichment and spread-plate technique for initial screening. Seven chitinase-producing strains are isolated. The chitinase present in the culture supernatant of strain CS-01 possesses the maximum activity of 0.118 U/mL. Analysis of the morphological feature and the ITS rDNA sequence reveals that strain CS-01 belongs to Aspergillus fumigatus. Production of the chitinase is regulated by a inducible way and the maximum activity appears at 36 h in colloidal chitin culture. Purification of the chitinase is carried out by salting out, gel filtrate chromatography and anion exchange chromatography sequentially. Native-PAGE and SDS-PAGE indicate that the chitinase from A. fumigatus CS-01 is a monomer with the relative molecular mass estimated to be 4.50×10⁴. Its maximum activity appears at pH 5 and 55 °C. The chitinase is stable at pH 4.0–7.5 and below 45 °C. Foundation item: Projects(50621063, 50674101) supported by the National Natural Science Foundation of China     

负载活性组分的核壳结构纤维膜的制备及性能

采用同轴静电纺丝技术将蛛丝蛋白（Ss）和美洲大蠊提取物（PAE）分别负载于纳米纤维的壳层与核层。随着Ss的增加,纤维直径从350 nm降至280 nm,核层直径由120nm升至140 nm,壳层厚度由115 nm降至70 nm。Ss的加入使纳米纤维膜具有良好的机械性能和亲水性,纳米纤维膜的拉伸强度可达到4.31 MPa,溶胀率可达到150%,水蒸气透过率可达到1834 g/(m2?24h),水接触角减小到 32.7 ?。纳米纤维膜核壳结构能够有效抑制药物突释,实现药物长效释放,7天内药物释放可达77%;纳米纤维膜能够有效抑制细菌生长,促进细胞增殖,相较于未负载Ss的纳米纤维膜,负载20%Ss的纤维膜的细胞增殖效果提高25%,说明Ss和PAE在伤口愈合过程中能够起到协同作用。     

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 ...     

市售蒲公英片剂中总酚酸的含量测定

以咖啡酸为对照,采用三氯化铁-铁氰化钾比色法在764 nm波长下测定7个不同厂家蒲公英片剂中总酚酸的含量。结果:不同厂家生产的蒲公英片剂中总酚酸的含量差异显著,含量最高达77.60 mg/g,最低仅为23.37 mg/g,含量由高到低依次为河南C厂,吉林G厂,河南B厂,河南A厂,山西F厂,河南D厂和广西F厂。该方法稳定可靠,重复性及精密度良好,平均加样回收率为99.29%,RSD为1.39%,可以用于蒲公英片剂中总酚酸的含量的测定。     

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.     

喜温嗜酸硫杆菌YN12菌株的鉴定及其镉抗性能

自云南酸性热泉水样中分离出一株中度嗜热硫氧化菌YN12.对其形态特征和生理生化特性以及16S rDNA序列分析结果证明,该菌株归属于喜温嗜酸硫杆菌(Acidithiobacillus caldus).重金属抗性实验表明,YN12菌株对3CdSO4-8H2O具有超强抗性,其最高初始Cd2 耐受浓度达4.8 g/L.在此基础上,不断提升3CdSO4-8H2O浓度,其最终Cd2 耐受浓度可达31.5 g /L(相当于3CdSO4-8H2O 210 g/L).在该最终Cd2 耐受浓度下,经过连续3代的适应性生长,YN12菌株的生长速度和硫氧化活性均能得到较好的恢复.     

Full structure building and docking of NifS from extremophile Acidithiobacillus ferrooxidans

The gene iscS-2 from extremophile Acidithiobacillus ferrooxidans may play a crucial role in nitrogenase maturation. To investigate the protein encoded by this gene, a reliable integral three-dimensional molecular structure was built. The obtained structure was further used to search binding sites, carry out the flexible docking with cofactor pyridoxal 5＇-phosphate（PLP） and substrate cysteine, and identify its key residues. The docking results of PLP reveal that the residues of Lys203, His100, Thr73, Ser200, His202, Asp177 and GlnlS0 have large interaction energies and/or hydrogen bonds fixation with PLP. The docking results of cysteine show that the amino group in cysteine is very near His100, Lys203 and PLP, and the interaction energies for cysteine with them are very big. These identified residues are in line with the experimental facts of NifS from other sources. Moreover, the four residues of Asn152, Val179, Ala102 and Met148 in the PLP docking and the two residues of Lys208 and Alal02 in the cysteine docking also have large interaction energies, which are fitly conserved in NifS from all kinds of sources but have not been identified before, According to these results, this gene encodes NifS protein, and the substrate cysteine can be effectively recruited into the active site. Furthermore, all of the above detected key residues are directly responsible for the binding and/or catalysis of PLP and cysteine.