Isolation of a strain of <Emphasis Type="Italic">Acidithiobacillus caldus</Emphasis> and its role in bioleaching of chalcopyrite

A moderately thermophilic and acidophilic sulfur-oxidizing bacterium named S₂, was isolated from coal heap drainage. The bacterium was motile, Gram-negative, rod-shaped, measured 0.4 to 0.6 by 1 to 2 μm, and grew optimally at 42–45°C and an initial pH of 2.5. The strain S₂ grew autotrophically by using elemental sulfur, sodium thiosulfate and potassium tetrathionate as energy sources. The strain did not use organic matter and inorganic minerals including ferrous sulfate, pyrite and chalcopyrite as energy sources. The morphological, biochemical, physiological characterization and analysis based on 16S rRNA gene sequence indicated that the strain S₂ is most closely related to Acidithiobacillus caldus (>99% similarity in gene sequence). The combination of the strain S₂ with Leptospirillum ferriphilum or Acidithiobacillus ferrooxidans in chalcopyrite bioleaching improved the copper-leaching efficiency. Scanning electron microscope (SEM) analysis revealed that the chalcopyrite surface in a mixed culture of Leptospirillum ferriphilum and Acidithiobacillus caldus was heavily etched. The energy dispersive X-ray (EDX) analysis indicated that Acidithiobacillus caldus has the potential role to enhance the recovery of copper from chalcopyrite by oxidizing the sulfur formed during the bioleaching progress.     

氧化亚铁硫杆菌亚铁氧化活性与其对低品位铜矿浸矿速率关系的研究

氧化亚铁硫杆菌是一个具有很强生物浸矿能力的细菌,本文对3株分离得到的氧化亚铁硫杆菌及一株来自菌种中心(Acidithiobacillus ferrooxidans A．f)的铁氧化活性及其这些菌株对低品位黄铜矿浸出速率进行了研究。结果显示,在所有的4株A．f菌中,菌株CMS—F1和F10—ATCCC23270的铁氧化活性较高,其对黄铜矿生物浸出速率也高。进一步分析亚铁氧化活性对生物浸矿效率的影响时发现,在A．f菌中,氧化活性高的菌株,其对低品位黄铜矿的生物浸出效果也高。     

Comparative Leaching of Chalcopyrite by Selected Acidophilic Bacteria and Archaea

A systematic study of the bioleaching of chalcopyrite (CuFeS 2 ) was conducted using axenic cultures of 11 species of acidophilic Bacteria and Archaea to obtain a direct comparison of the microbial chalcopyrite leaching capabilities of the different cultures and to determine the factors that affect Cu release. The characteristics of chalcopyrite leaching by the moderate thermophile Sulfobacillus thermosulfidooxidans , the mesophile Acidithiobacillus ferrooxidans , and the thermophile Acidianus brierleyi were used to elucidate the leaching process. Moderately thermophilic cultures of Sulfobacillus acidophilus, Acidimicrobium ferrooxidans , and Acidithiobacillus caldus were used to study the effects of different metabolic capabilities and relate those to leaching efficiency. The greatest rate of Cu solubilization from chalcopyrite was achieved at high temperatures (up to 70°C) at redox potentials below +550 mV (Ag/AgCl). The enhanced Cu solubilization observed at high temperatures resulted from accelerated chemical reaction rates, rather than from the rates at which individual acidophiles generated the mineral leaching reactants such as Fe 3+ .     

乳扇制品中乳酸杆菌的分离鉴定及16S rRNA序列同源性分析

目的乳扇是云南大理白族的一种传统乳制品,明确大理乳扇制品中乳杆菌的多样性及优势种群分布,为科学利用奠定基础。方法采用表型鉴定及16S r RNA鉴定方法,对10个家庭作坊的大理乳扇制品中的乳杆菌进行了分离鉴定。结果共分离到50株乳杆菌,通过表型鉴定为8个种,包括植物乳杆菌10株、德氏乳杆菌7株、发酵乳杆菌6株、干酪乳杆菌6株、棒状乳杆菌4株、鼠乳杆菌2株、弯曲乳杆菌3株和食果糖乳杆菌2株;06422和06430两株表型鉴定未能定种,进一步通过16S r RNA鉴定为植物乳杆菌和马酒乳杆菌,06422株与植物乳杆菌L.arizonensin、L.pentosus和L.plantarum P158的同源性分别是100%、100%和99.9%,与乳杆菌属其它种的同源性为83.4%(L.gallinarum)至93.5%(L.brevis),06430株与L.kefiranofaciens.subsp.Kefirgranum的16S r RNA同源性是99.9%,与乳杆菌属其它种的同源性为83.7%(L.plantarum P158)至96.3%(L.acidophilus)。结论大理乳扇制品中有9种乳杆菌,其优势种群为植物乳杆菌、德氏乳杆菌、发酵乳杆菌和干酪乳杆菌等四种。     

一株产耐热普鲁兰酶菌株Anoxybacillus sp.LM14-2分离鉴定及酶学性质研究

从云南轮马热泉下游淤泥中筛选得到了一株产耐热普鲁兰酶菌株LM14-2.根据形态特征及16S rRNA序列同源性分析,初步判定为Anoxybacillus sp.LM14-2.该菌株发酵上清液中有耐热普鲁兰酶积累,其反应最适pH值为6.0,最适温度为70℃.利用染色体步移技术获得了完整的普鲁兰酶编码基因(HQ660582),经序列相似性进一步分析,确定该蛋白与Ⅰ型普鲁兰酶保守区b相吻合.通常的普鲁兰酶在高温下很快失活,难以满足淀粉加工,洗涤剂等相关工业的需求,而该新型的耐热普鲁兰醇的作用温度广泛,热稳定性较好,65℃保温55 h后达到其半衰期,具有广阔的开发应用前景.     

功能菌群耦合黄铁矿浸出软锰矿的研究

【目的】将3种不同来源的环境样品混合后接种至含1%黄铁矿和1%软锰矿的培养基中进行富集培养,初步得到有一定浸矿功能的混合微生物菌群。【方法】菌群继续用于黄铁矿和低品位软锰矿共同浸出,设置未接种的体系作为对照。【结果】对浸出过程中菌群结构的变化、pH、锰浸出率和浸出残渣的成分进行分析,结果发现接种过微生物菌群的浸出体系在反应15 d后,锰浸出率达到92.48%,远高于未接菌对照组的40.34%;菌群中Thiomonas sp.所占比例从最初的2%上升到浸出结束时的93%。实验组的pH从最初的4.0下降到2.5;X射线衍射(XRD)分析发现,通过生物作用浸出的残渣中含有黄钾铁矾,说明生物代谢产生了大量的硫酸。【结论】证明微生物在两矿浸出过程中通过促进黄铁矿解离,维持体系低pH等作用加速反应的进行。结果为进一步研究微生物浸矿的作用机制和开发低品位锰矿的生物浸出工艺打下了基础。     

Genomic and phenotypic heterogeneity of Acidithiobacillus spp. strains isolated from diverse habitats in China

The genetic variability among 32 Chinese Acidithiobacillus spp. environmental isolates and four reference strains representing three recognized species of the genus Acidithiobacillus was characterized by using a combination of molecular methods, namely restriction fragment length polymorphisms of PCR-amplified 16S rRNA genes and 16S-23S rRNA gene intergenic spacers, repetitive element PCR, arbitrarily primed PCR and 16S rRNA gene sequence analyses. 16S rRNA gene sequences revealed that all Acidithiobacillus spp. strains could be assigned to seven groups, three of which encompassed the Acidithiobacillus ferrooxidans strains from various parts of the world. A comparative analysis of the phylogenetic Group 1 and 2 was undertaken. Restriction fragment length polymorphism results allowed us to separate the 35 Acidithiobacillus strains into 15 different genotypes. An integrated phenotypic and genotypic analysis indicated that the distribution of A. ferrooxidans strains among the physiological groups were in agreement with their distribution among the genomic groups, and that no clear correlation was found between the genetic polymorphism of the Acidithiobacillus spp. strains and either the geographic location or type of habitats from which the strains were isolated. In addition, five unidentified sulfur-oxidizing isolates may represent one or two novel species of the genus Acidithiobacillus. The results showed that the Chinese Acidithiobacillus spp. isolates exhibited a high degree of genomic and phenotypic heterogeneity.     

猪源绿色气球菌的分离鉴定与药敏特性研究

目的鉴定研究2006年和2008年本实验室分别从广东清远和广西北流两个猪场发病小猪的膝关节积液中分离到2株呈四联状或成对排列,在山羊血琼脂平板上能形成明显的α-溶血圈的G+球菌。方法采用小白鼠致病性试验、细菌常规生理生化鉴定、药敏试验、耐药基因检测及16S rRNA序列分析等方法对上述分离的2株细菌进行鉴定及药敏特性研究。结果确定这2株G+球菌为正常情况下非致病性绿色气球菌(登录号分别为:GQ161096;GQ161097)。系统发育分析表明,两分离株与绿色气球菌15MS(登录号:EU075039.1)同源性分别高达99.4%和98.7%。药敏试验及耐药基因检测发现,这2株绿色气球菌除了对新霉素、氟哌酸、恩诺沙星、菌必治和环丙沙星等5种药物呈高敏外,对先锋V等13种抗菌素均不敏感。耐药基因检测结果表明,GXBL-1可检出6个耐药基因,GDQY-1则可检出多达10个耐药基因。结论从这2株分离株耐药谱检测结果可以看出,正常菌株同样携带多重耐药基因,存在着通过质粒转座子和整合子将耐药基因转移给敏感菌,导致耐药性传播的可能,应引起足够重视。     

大肠杆菌磷酸果糖激酶基因在极端嗜酸性氧化硫硫杆菌中的表达

构建了含大肠杆菌磷酸果糖激酶(EC 2.7.1.11)基因pfkA的重组质粒pSDK1,利用大肠杆菌pfk缺陷株筛选含目的基因的重组质粒,通过接合转移的方式将其导入氧化硫硫杆菌TtZ2中,接合转移频率达2.6×10-6。重组质粒在TtZ2中有较好的稳定性,在无选择压力条件下传代50次基本保持稳定(重组质粒保留68%以上)。酶活性测定、SDSPAGE及RTPCR结果表明,pfkA基因在氧化硫硫杆菌中得到表达,但其表达水平低于大肠杆菌。葡萄糖可促进含pSDK1的氧化硫硫杆菌TtZ2的生长,而对照菌株的生长则未受明显影响,说明重组菌可部分利用葡萄糖作为碳源生长。