表面活性剂Tween-80对Acidithiobacillus ferrooxidans硫氧化和硫代谢相关蛋白质基因表达的影响(英文)

研究了表面活性剂 Tween-80 对 Acidithiobacillus ferrooxidans ATCC 23270 生长、硫氧化和硫代谢相关典型基因表达的影响。结果表明,当培养基中含有 10 2g/L Tween-80 时,A. ferrooxidans 的生长以及其对不溶性底物(S0和 CuFeS2)的代谢得到了促进。在该条件下,经过 24 d 的生物浸出,黄铜矿的铜离子浸出率比对照组(不含 Tween-80)高 16%。FT-IR 光谱分析表明,这可能是由于 Tween-80 的存在而导致胞外多聚物成分发生变化而引起的。用 RT-qPCR 来分析 17 个硫代谢相关基因在 Tween-80 存在时的表达差异。胞外蛋白质基因表达下调表明了Tween-80 对细菌硫吸附作用的影响。硫代谢相关酶基因表达水平的变化为硫代谢的研究提供了参考。     

Mutagenic breeding of silver-resistant Acidithiobacillusferrooxidans and exploration of resistant mechanism

The silver-resistant Acidithiobacillus ferrooxidans were isolated from 22 acid mine drainage （AMD） samples collected from Dexing Copper Mine and Chengmen Mountain Mine, Jiangxi Province, China. Isolate DX16 is obtained from the sample taken from Dexing Copper Mine and still carries out ferrous ion oxidation when incubated in 9K medium containing silver nitrate （240 mg/L）. While isolate HI, a less resistant strain taken from Yin Mountain Mine, has a tolerate level of only 60 mg/L. Based on 16S ribosomal DNA sequencing, both bacterial 16SrDNA sequences are 100% similar to Acidithiobacillus ferrooxidans ATCC 23270. Through ultraviolet irradiation induced mutations, isolate mDX16 that is obtained from DX16 carries out ferrous ion oxidation when incubated in 9K medium containing higher concentration of silver nitrate （250 mg/L）. When silver-resistant gene （SilC） analysis is carried out on the two isolates, it is seen that this gene was absent in both.     

Repetitive sequence based polymerase chain reaction to differentiate close bacteria strains in acidic sites

To study the diversity of bacteria strains newly isolated from several acid mine drainage（AMD） sites in China, repetitive sequence based polymerase chain reaction （rep-PCR）, a well established technology for diversity analysis of closely related bacteria strains, was conducted on 30 strains of bacteria Leptospirillum ferriphilium, 8 strains of bacteria Acidithiobacillus ferrooxidans, as well as the Acidithiobacillusferrooxidans type strain ATCC （American Type Culture Collection） 23270. The results showed that, using ERIC and BOX primer sets, rep-PCR produced highly discriminatory banding patterns. Phylogenetic analysis based on ERIC-PCR banding types was made and the results indicated that rep-PCR could be used as a rapid and highly discriminatory screening technique in studying bacterial diversity, especially in differentiating bacteria within one species in AMD.     

Purification and enzymatic characteristics of cysteine desulfurase, IscS, in Acidithiobacillus ferrooxidans ATCC 23270

A cysteine desulfurase protein,IscS,was encoded by the operon iscSUA in Acidithiobacillus ferrooxidans.The gene of IscS from Acidithiobacillus ferrooxidans ATCC 23270 was cloned and expressed in Escherichia coli.The protein was purified by one-step affinity chromatography to homogeneity.The final protein yield after affinity chromatography was 12.9%.The enzyme was characterized for thermal stability,pH and kinetic parameters.The molecular mass of recombinant IscS was 46 ku by SDS-PAGE.The optimum pH was 8.0-8.5.The enzyme had a temperature optimum at 30 ℃ and was relatively stable at 40 ℃,with 67% loss of activity.1,5-I-AEDANS significantly inhibited IscS activity.Kinetic parameters Km and Vmax were found to be 0.11 mmol/L and 2.57 μmol/(L-min).     

Isolation and characterization of acidophilic bacterium from Gaofeng Mine in China

An acidophilic, chemolithotrophic and ferrous oxidizing bacterium strain GF was isolated from the acid mine drainage （AMD） of Gaofeng Mine, Guangxi Province, China using 9K enrichment medium, and then purified on solid ferrous-agarose medium. The physiological experiments show that it can use ferrous or sulfur as sole energy and a low level （0.1%, w/v） of peptone can accelerate the growth of the isolated strain. The optimum pH and temperature for growth are 2.0 and 30 ℃, respectively. The isolated strain shares 99.64% identities of 16S rRNA gene with the type strain Acidthiobacillusferrooxidans ATCC 23270 and 100% identities of iro gene （CDS） with A.ferrooxidans strain Fe-1. These results show that the strain can be considered as A cidthiobacillus ferrooxidans. Because of the high activity of oxidizing ferrous and sulfide mineral, strain GF was used in bioleaching of marmatite. The Zn concentration is 0.273 g/L under the steriled control and 7.30 g/L with adapted GF strain incubated after 29 d in leaching marmatite. The isolated strain GF can be used to leach marmatite in industry application.     

生物浸铀中影响嗜酸氧化亚铁硫杆菌活性的氟毒物活性形态(英文)

为了确定浸矿菌耐氟的机制,在氟化物存在的条件下,驯化铀矿浸出菌嗜酸氧化亚铁硫杆菌ATCC23270,研究溶液中含不同氟浓度、不同pH值时铀矿浸出菌的活性变化,以及有无蛋白酶K处理时铀矿浸出菌细胞内氟浓度的变化情况。采用铂电极和Ag/AgCl参比电极测量氧化还原电位,以作为细菌不同活性的参照指标,采用氟离子选择性电极测定细胞内的氟浓度。结果表明,真正影响铀矿浸出菌活性的是HF,溶液pH值增加以及溶液中与氟有较强络合能力的离子浓度的变化,也会引起耐氟菌假象的出现。浸矿菌的耐氟能力可能与细胞壁和细胞膜上的一些蛋白密切相关。     

Purification and enzymatic properties of arsenic resistance protein ArsH from heterogeneous expression in E.coli BL21

Four arsenic-resistance genes(arsB,arsC,arsH,arsR) have been discovered in Acidithiobacillus ferrooxidans.Their gene sequences have been identified and three different arsenic-resistance mechanisms have been elucidated.However,the function of the arsH gene in At.ferrooxidans remains unclear.In order to evaluate the function of the arsH gene,we cloned it and expressed it in Escherichia coli.The protein was purified and its relative molecular mass was determined by SDS-PAGE(Sodium dodecyl sulfate-polyacrylamide gel electrophoresis).The results indicated that the relative molecular mass of the purified ArsH was approximately 29 kDa.The purified protein ArsH from E.coli BL21 was a flavoprotein that oxidized in vitro NADPH with an optimal pH of 6.4.     

Polypyrrole colloidal nanospheres as an effective fluorescent sensing platform for DNA detection

In the present study, we demonstrate the first use of polypyrrole colloidal nanospheres (PPyCNPs) as an effective sensing platform for fluorescence-enhanced DNA detection by the following two steps: (1) PPyCNP adsorbs and quenches a dye-labeled single-stranded DNA (ssDNA) probe; (2) The subsequent hybridization of the probe with its target produces a double-stranded DNA (dsDNA) which detaches from PPyCNP, leading to recovery of dye fluorescence. The present system shows a detection limit as low as 1 nM and has a high selectivity down to single-base mismatch.     

Study on bioleaching of refractory gold ore (Ⅰ)──Mechanism on bioleaching of pyrite by Thiobacillus ferrooxidans

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EPS对Acidithiobacillus.ferrooxidans在黄铜矿与黄铁矿表面吸附的影响

运用超声波结合离心方法提取Acidithiobacillus.ferrooxidans的胞外多聚物（EPS）,用2-酮基-3-脱氧辛酸（KDO）作为表征EPS含量的指标,采用分光光度法对该提取方法进行评估。通过一系列对比性实验研究EPS对Acidithiobacillus ferrooxidans在黄铜矿与黄铁矿表面吸附的影响。将未处理的Acidithiobacillus ferrooxidans与经处理脱去EPS层的Acidithiobacillus ferrooxidans分别与EPS悬液、Fe^2＋和Fe^3＋重新混合,在2h的反应过程中,实时检测混合液中游离的细菌含量。结果表明：细菌表面EPS的存在是其吸附于黄铁矿和黄铜矿表面的一个重要因素。当缺失EPS层时,Acidithiobacillus ferrooxidans吸附于矿物表面的能力有所下降,但当重新加入EPS混合液时这种能力能大部分恢复,这种恢复程度在黄铁矿中较黄铜矿中更加明显。当加入EPS和Fe3＋时其细菌吸附于黄铜矿表面的程度有所升高,而加入Fe2＋时吸附程度明显降低,这个结果表明静电的相互作用也许是细菌最初吸附于矿物表面的一个主要原因,并且这也许是细菌生产EPS的一种驱动力以使细菌吸附于硫化铜矿物后重新获得其吸附能力。     

氧化亚铁硫杆菌和氧化硫硫杆菌的协同作用对Q235钢腐蚀行为的影响

采用失重法、交流阻抗测试和扫描电镜等手段研究了氧化亚铁硫杆菌(T.f)和氧化硫硫杆菌(T.t)的协同作用对Q235钢腐蚀行为的影响。结果表明,T.f和T.t的协同作用加剧了Q235钢的均匀腐蚀速率,混合菌体系中Q235钢的腐蚀失重远大于两种微生物单独存在体系。显微分析结果表明,T.t体系中金属没有出现点蚀,混合菌体系中Q235钢的点蚀坑较T.f体系中的小而浅,T.t的存在降低了Q235钢的局部腐蚀。     

氧化亚铁硫杆菌浸矿体系中黄铁矿的电化学行为(英文)

运用循环伏安、稳态极化扫描和交流阻抗等电化学测试方法,研究黄铁矿在氧化亚铁硫杆菌浸矿体系和无菌酸性体系下的电化学氧化机理。结果表明,在无菌和A.ferrooxidans菌存在的条件下,黄铁矿的氧化反应分为两步:第一步是黄铁矿氧化生成元素S;第二步是元素S被氧化生成SO42-。加入A.ferrooxidans后黄铁矿的氧化机理没有发生改变,但是氧化速度加快。随着黄铁矿与A.ferrooxidans作用时间的延长,极化电流密度增加,黄铁矿表面钝化膜溶解的点蚀电位降低。在细菌存在的条件下,电极的阻抗值下降,表明微生物的存在加速了黄铁矿电极的腐蚀作用,有利于黄铁矿的氧化溶解。     

嗜酸氧化亚铁硫杆菌亚铁氧化系统研究进展

嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)是目前研究得最多的浸矿细菌,其能量代谢途径复杂多样。在有氧条件下,A.ferrooxidans以氧化Fe2 、H2或(和)各种还原性硫化物提供能量来生长,在亚铁氧化系统中,A.ferrooxidans的各种菌株氧化亚铁后产生的电子经大致相同的传递途径传递给最终电子受体O2,但是最初电子受体可能有所不同。讨论了A.ferrooxidans亚铁氧化系统中电子顺电势梯度传递的各个电子传递载体的组成,基因结构和特征以及可能的相互作用机制;同时,介绍了A.ferrooxidans生长过程中,少量电子经细胞色素bc1复合体逆电势梯度传递、参与还原力NAD(P)H的生成和CO2固定过程中可能存在的电子传递模式,以及A.ferrooxidans在不同生长基质中生长时rus操纵子的转录调控模式。     

Purification and enzymatic characteristics of cysteine desulfurase, IscS, in Acidithiobacillus ferrooxidans ATCC 23270

A cysteine desulfurase protein, IscS, was encoded by the operon iscSUA in Acidithiobacillusferrooxidans. The gene of IscS from Acidithiobacillus ferrooxidans ATCC 23270 was cloned and expressed in Escherichia coil The protein was purified by one-step affinity chromatography to homogeneity. The final protein yield after affinity chromatography was 12.9%. The enzyme was characterized for thermal stability, pH and kinetic parameters. The molecular mass of recombinant lscS was 46 ku by SDS-PAGE. The optimum pH was 8.0-8.5. The enzyme had a temperature optimum at 30 ℃ and was relatively stable at 40 ℃, with 67% loss of activity. 1,5-I-AEDANS significantly inhibited IscS activity. Kinetic parameters Km and Vmax were found to be 0.11 mmol/L and 2.57 μmol/（L.min）.     

Toward intelligent polymers: DNA sensors based on oligonucleotide-functionalized polypyrroles

A conjugated polymer can be considered as tri-dimensional network of intrinsically conducting macromolecular wires, able to transport signals. When further functionalized with prosthetic groups showing recognition properties, such polymer architecture mimics the nervous system existing in living beings. With this aim, we have developed a new type of electrochemical sensors, based on electroactive polypyrrole functionalized with oligonucleotide (ODN). At first, we analyzed the experimental conditions for building such modified electrode, showing a high electroactivity in aqueous medium. We developed a new route for the functionalization of polypyrrole, involving a precursor polypyrrole bearing an easy leaving ester group, on which an amino-labelled ODN can be directly substituted. The electrochemical response of this polypyrrole electrode functionalized with an ODN probe has then been analyzed in various aqueous media, containing either complementary or noncomplementary ODN targets. Results show that the cyclic voltammogram of ODN-functionalized polypyrrole is not modified when in presence of a noncomplementary ODN in solution. On the other hand, a significant modification of the voltammogram is observed upon addition of a complementary ODN target, to the electrolytic medium, which indicates that specific hybridization has occurred between the polypyrrole-grafted ODN probe and its complementary ODN target in solution. This biological recognition can be quantitatively determined by an amperometric analysis, and the limit of detection of this electrochemical biosensor is about 10⁻¹¹ mol, without any signal processing. These results confirm that functionalized polypyrroles act as macromolecular wires able to transduce biological information into molecular signals.