氧化亚铁硫杆菌最佳生长条件的初步探索

氧化亚铁硫杆菌生长活性影响因素有很多，其中主要的是温度、pH、培养基的量以及接种量等。用比浊法以及二价铁离子的变化为指标，对氧化亚铁硫杆菌的生长条件进行初步研究，得出其最佳生长条件为：温度28℃左右，初始pH为2．3左右，培养基装量为50～100mL／250mL。接种量为10％。     

JX嗜酸异养菌与氧化亚铁硫杆菌联合浸铀的研究

从江西某铀矿酸性矿坑水中筛选出了一株JX嗜酸异养菌和一株氧化亚铁硫杆菌,将它们按不同的接种比例和接种时间接种于加了铀矿粉的9K培养基中,进行了联合浸铀试验。结果表明:加入异养菌后,浸出体系中Fe2+氧化速率、pH下降速度及Eh的上升速度都有所减慢;不同接种比例试验的铀的最终浸出率均在97%左右;不同接种时间试验的铀最终浸出率均在98%左右;JX异养菌的加入,对氧化亚铁硫杆菌浸铀没有起到明显的促进作用。     

耐高矿化度浸矿菌的驯化及浸铀效果

从721铀矿石样中分离出的一株氧化亚铁钩端螺旋菌(Leptospirillums ferrooxidans)与氧化亚铁硫杆菌(Thiobacillus ferrooxidans)的混合菌株,经不同条件的驯化及紫外线诱变处理后,可在高矿化度(M>50g/L)、低pH(pH=1.4)的铀矿石酸化液中良好生长。实验室槽浸实验表明,这一混合菌株对低pH、高矿化度的浸出体系具有良好的适应性,仅用7天时间,渣计浸出率达90.06%,浸出过程中未出现铁损失。     

酸化预处理加快浸铀细菌生长速度

对铀矿石进行酸化预处理,然后菌浸。结合对照试验结果,酸化预处理有利于氧化亚铁硫杆菌和氧化硫硫杆菌对铀矿石的适应,可以加快其生长速度。     

在空气提升器中用铁氧化钩端螺旋菌从低品位复杂硫化物矿石中生物浸出锌

A．Giaveno等利用逆流空气提升器，研究了以当地铁氧化钩端螺旋菌（Lf-LS04）从La Silvita和La Resbalosa（阿根廷巴塔哥尼亚）低品位复杂硫化物矿石中生物浸出锌。反应器中装有pH为1．8的无铁9K介质，矿物粒度小于74μm，矿浆密度1％，表面空气速度0．01m／s。2种硫化物矿石（主要是La Silvita矿石）的锌回收率均高于用以前收集的嗜酸氧化亚铁硫杆菌的回收率。     

用嗜酸氧化亚铁硫杆菌和曲霉菌从Sukinda铬铁矿覆盖层中提取镍

S．Mohapatra等研究了用2种真菌（黑曲霉菌和烟曲霉菌）和一种嗜温、嗜酸混合培养基（占优势的是嗜酸氧化亚铁硫杆菌）从低品位铬铁矿覆盖层中回收镍。研究了如温度，pH和矿浆密度等因素对铬铁矿覆盖层浸出的影响。结果表明，嗜酸氧化亚铁硫杆菌培养基在30～37℃范围内可有效溶解镍，而在更高温度下，如45℃，则没有溶解镍的能力。     

不同初始条件对细菌浸出电子线路板中铜的影响

利用筛选的氧化亚铁硫杆菌,研究了初始pH、Fe2+质量浓度以及氧化亚铁硫杆菌的驯化对电子线路板中金属铜浸出的影响。结果表明:酸性条件有利于保持铁离子浓度,从而提高浸出速度,浸出最佳pH为1.5;初始Fe2+质量浓度越高,越有利于铜的浸出,最佳Fe2+质量浓度为9.0 g/L;氧化亚铁硫杆菌驯化与否对铜的浸出影响不大。     

冶金废渣中浸矿菌种的筛选及其生长特性分析

为了探讨细菌对含金废渣的浸出工艺,本研究以灵宝某黄金冶炼厂冶金废渣为原料,利用9K培养基从中经富集并分离纯化了活性较好的JK3菌株,初步鉴定为氧化亚铁硫杆菌,并对影响该菌株的环境因子进行了初步分析。结果表明在温度、pH值适宜的前提下,用JK3菌株对含金废渣进行浸出浸矿时,适当加大初始接种量,可以加快Fe~(2+)氧化速率。     

UO22+对氧化亚铁硫杆菌生长活性的影响

研究了在温度30℃,pH 2．0的常用浸出条件下,UO_2~(2 )对氧化亚铁硫杆菌(T．f)生长活性的影响。结果表明,UO2~(2 )对氧化亚铁硫杆菌的生长活性有较大影响,具体表现在细菌生长的停滞期和对数期均较长,Fe~(2 )的氧化速度慢。在含一定浓度UO_2~(2 )的培养基中驯化的T．f菌,能耐受[UO__2~(2 )]为400～1200 mg/L,而且对Fe~(2 )的氧化速率加快。     

一种活性炭催化细菌浸钴的方法

正一种活性炭催化细菌浸钴的方法,属于生物冶金技术领域,按以下步骤进行:(1)将含有氧化亚铁微螺菌、嗜酸氧化亚铁硫杆菌和嗜酸氧化硫硫杆菌的混合菌液接种到培养基中制成培养液;(2)调节pH值后置于恒温振荡器中培养,获得培养菌液;(3)将硫铜钴矿粉加入到培养菌液中制成矿浆,再     

Acidithiobacillus ferrooxidans对软锰矿浸出的影响

利用循环伏安、交流阻抗谱和极化曲线研究了Acidithiobacillus ferrooxidans对软锰矿在模拟浸出溶液(9K基础培养基, A.ferrooxidans, Fe (Ⅲ), A.ferrooxidans+Fe (Ⅲ))中电化学腐蚀行为的影响; 利用模拟有菌/无菌浸出溶液中钝化膜的Mott-Schottky理论比较了有无细菌存在情况下形成的钝化膜的优劣性.结果表明, A.ferrooxidans促进MnO₂/Mn2+氧化还原转化, 催化MnO₂/Mn (OH)₂电极反应; 加速软锰矿/溶液界面电子交换, 无铁存在时A.ferrooxidans使电荷转移内阻降低34%, 比含Fe (Ⅲ)无菌体系低11%;引起软锰矿电极极化, 增强其氧化活性; 加速MnO₂向MnO·OH转化及其产物扩散.A.ferrooxidans与软锰矿作用更倾向于间接作用机理.在选取的各模拟电解液(pH值为2.0)中, 0.2~0.4 V区间内软锰矿形成耗尽层, 在模拟浸出溶液中形成的钝化膜都表现出p-n-p-n型半导体性能.在选取的0.2 V极化电位下, 无铁时引入A.ferrooxidans使膜中的施主/受主密度减少, 细菌含有多种基团参与半导体/溶液界面电子转移反应, 接受界面间自由电子或填充空穴, 促使软锰矿与溶液界面物质交换变频繁; 含铁溶液中加入A.ferrooxidans使得钝化膜受主/施主密度增大, A.ferrooxidans降低了膜的耐腐蚀性, 因而促进软锰矿浸出.      

永平铜矿浸矿细菌最佳生长条件的研究

对从永平铜矿酸性矿坑水中分离出的浸矿细菌进行了最佳生长条件的研究。结果表明,在9K+S培养基中,接种量为20%,pH为1 80,Fe2+浓度为3g/L,总铁为4g/L的条件下,既有利于细菌的生长,又有利于减少铁的沉淀,同时有利于矿物的浸出。     

嗜酸氧化亚铁硫杆菌和嗜酸氧化硫硫杆菌联合浸出高锡多金属硫化矿

高锡多金属硫化矿选冶过程中,硫化矿的存在严重影响了锡的回收率,目前国内外对锡矿生物法脱硫的报道极少,针对上述问题,研究采用嗜酸氧化亚铁硫杆菌和嗜酸氧化硫硫杆菌联合浸出高锡硫化矿.通过摇瓶实验考察嗜酸氧化亚铁硫杆菌、嗜酸氧化硫硫杆菌纯菌及混合菌对锡矿脱硫的影响,并采用实时定量PCR技术(qRT-PCR)对生物浸出过程中2种菌的动态变化进行了分析.结果表明:混合菌浸出优于纯、菌浸出,能够有效地提高脱硫率,当pH为2.0,转速170 r/min,温度30 ℃,矿浆密度为10 %时,混合菌在18天内可使锡矿中的硫脱除率达到97 %.混合菌浸矿初期(第6天),嗜酸氧化亚铁硫杆菌是优势菌种,所占比例为69.4 %, 浸矿中后期,嗜酸氧化硫硫杆菌含量逐渐上升,并成为优势菌种,在稳定期(第24天)比例达到58.3 %.以上结果为锡矿生物法脱硫技术的开发提供了一条新的思路.      

黄铁矿促进黄铜矿微生物浸出影响因素

采用摇瓶实验,以氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,At.f)浸出黄铁矿-黄铜矿,重点研究了基础培养基、矿物配比和粒度组成等因素的影响.黄铁矿能促进黄铜矿的微生物浸出,以采用无Fe 9K培养基效果较好,它对应铜浸出率是9K培养基的1.68倍;采用宽粒级矿物时铜浸出效果较好,且铜浸出率与黄铁矿和黄铜矿的质量比有关,当质量比为2:2时铜浸出率最高可达45.58%;黄铁矿含量大小是影响铜浸出率高低的实质,当质量比小于等于5:2时以At.f菌的氧化作用为主,当质量比为10:2时以硫化矿间的原电池效应为主.浸渣的X射线衍射分析表明,采用无Fe 9K培养基时浸渣中生成的钝化物黄钾铁矾较少,故黄铁矿可以很好地替代9K培养基中的FeSO₄,并能与黄铜矿形成原电池效应,从而促进铜的浸出.      

永平铜矿浸矿细菌驯化培养研究

以永平铜矿为研究对象,通过逐步模拟矿石环境,对浸矿细菌进行了矿石培养基与人工培养基配比的转代驯化培养研究。研究结果表明:S2-2+9K和S2-2+9K+S两个样品的细菌经过4次驯化后,溶液中Fe2+的转化速率明显提高,Fe的沉淀率明显减少,而pH逐渐下降;从调酸次数、幅度及pH下降的程度上分析,含矿石的9K+S培养基更有利于驯化硫杆菌;而从Fe2+的转化速率及Fe的沉淀率上分析,含矿石的9K培养基更有利于驯化铁杆菌;在细菌逐步驯化过程中,必须控制好合适的酸度条件,否则会造成大量Fe的沉淀。     

Time-dependent changes in the response of cartilage to static compression suggest interstitial pH is not the only signaling mechanism

The goal of the present study was to reexamine the role of interstitial pH in regulating the biosynthetic rate in cartilage tissue by addressing two research questions: (a) Do small, short-term changes in interstitial pH, induced independently by two different mechanisms (namely, by controlling the pH of the medium or by mechanical compression), result in biosynthetic rates commensurate with those expected from the "natural" relationship between interstitial pH and biosynthesis? and (b) Are the effects of changes in the pH of the medium or in compression the same for short-term (14-hour) and long-term (60-hour) exposures? Biosynthetic rates were estimated from incorporation of sulfate and proline into explants of bovine epiphyseal cartilage during the final 14 hours of culture. These rates decreased with decreasing pH of the medium, with increasing compression, and with decreasing native glycosaminoglycan content; or, expressed in terms of interstitial pH, acidification induced by compression or by lowering the pH of the medium resulted in a decreased biosynthetic rate, whereas interstitial acidification effected by increasing glycosaminoglycan content enhanced it. When the time for which tissue was exposed to changes in the pH of the medium was increased from 14 to 60 hours, the relationship between the biosynthetic rate and the pH remained constant whereas the relationship between the biosynthetic rate and compression was reversed. These data suggest that the transduction mechanisms underlying the response to pH of the medium and compression differ and that some adaptation or stimulation by modest levels of compression can occur with longer exposures. Interstitial pH is not the sole determinant of biosynthesis, and it cannot really account for the long-term response of cartilage tissue to static compression.     

The effects of extracellular pH and calcium manipulation on protein synthesis and response to anoxia/aglycemia in the rat hippocampal slice

Extracellular pH modulates the function of the N-methyl-D-aspartate (NMDA) receptor, which may influence pathophysiological responses to glutamate. While damage due to oxygen and glucose deprivation or glutamate exposure is attenuated by acidification of the incubating medium of cultured neurons, neuron damage is enhanced in vivo following ischemia in hyperglycemic animals. A persistent inhibition of protein synthesis (to less than 5% of normoxic levels) is a reliable index of damage to neurons both in vivo and in the rat hippocampal slice. We explored the influence of extracellular pH and calcium manipulation on protein synthesis inhibition and energy failure due to anoxia/aglycemia or exposure to N-methyl-D-aspartate in the rat hippocampal slice. Moderate acidification of the medium during anoxia/aglycemia did not reduce the damage to protein synthesis in hippocampal neurons (9% of normoxic levels) and did not alter basal ATP levels or the rate of ATP depletion during anoxia/aglycemia. However, when calcium levels were lowered during the acidification and following the anoxia/aglycemia, protein synthesis was almost completely protected (84% of normoxic levels). Calcium reduction itself also attenuated the protein synthesis inhibition due to anoxia/aglycemia (to 55.6% of normoxic controls), but the protection was not as complete. In contrast, moderate acidification of the medium significantly reduced the damage to protein synthesis due to a brief exposure to NMDA (37% of control with NMDA, 78.9% of control with acidification during NMDA), even in the presence of extracellular calcium. Alkalinization of the medium exacerbated the protein synthesis inhibition following anoxia/aglycemia, and significantly reduced basal ATP levels (to 52% of normoxic control levels). Thus, pHo changes influence neuronal metabolism and response to anoxia/aglycemia. In addition, while acidification can reduce the excitotoxic damage caused by direct exposure to NMDA, it cannot reduce damage due to anoxia/aglycemia unless calcium is lowered concomitantly. Thus, both NMDA receptor activation and calcium are involved in the damage due to oxygen and glucose deprivation in the slice.     

次生硫化铜矿微生物浸出实验

微生物浸矿是提取低品位,难选次生硫化铜矿中有价元素的最有效方法之一.本研究利用嗜酸氧化亚铁硫杆菌(Acidthiobacillus ferrooxidans)浸取福建某难选次生硫化铜矿,依次开展浸矿菌富集培养实验、驯化转代实验和不同粒径配比下柱浸试验,获得了不同阶段的细菌浓度、pH值、铜浸出率等演变规律;并结合电子计算机断层扫描技术实现了柱内矿堆塌落、截面孔隙演化和浸矿机理研究.研究表明:细菌浓度和pH值均呈现缓慢增加后趋降低的趋势,浸柱中细菌增殖较慢,浸矿480 h后,细菌浓度仅为每毫升5×107个.浸矿过程中,细颗粒趋于向柱底迁移,矿堆出现塌落;柱顶孔隙率变大,增幅为6.65%,柱底孔隙率变小,降幅为8.29%;塌落程度与细粒含量成正比,最小塌落为1.7 mm,最大塌落为6.15 mm.入堆矿石粒径极大影响着柱浸体系的浸出效果.实验中柱浸B组(粒径r < 1 mm占28.41%)浸矿效果最佳,浸矿480 h后铜浸出率达47.23%.      

高碱脉石低品位铜镍复合矿的诱变细菌浸出

金川低品位铜镍复合矿为高碱脉石的氧化—硫化混和矿 ,矿区无土著浸矿细菌。采用经诱变改良的外源混合T .f浸矿菌和控制矿浆 pH(<4 ) ,有效地浸出了该复合矿中的镍和铜 ;控制矿浆pH在细菌生长最适的范围内 ,钙、镁实际耗酸分别只占其总含量的 2 2 %～32 % ;铜、镍在不同浸出阶段表现为相反的浸出行为 ,酸浸时铜优先被浸出 ,菌浸时镍优先被浸出 ;渣样分析表明硫化镍、硫化铜的浸出机制为间接作用。物相分析表明这些浸出行为与浸出对象的赋存状态有关。