微生物高盐渗透适应策略及其耐盐强化研究进展

高盐废水因具有硬度高、可生化性差、水质成分复杂等特点,是较难处理的工业废水之一。现有物化处理技术存在运行成本高、处理效率低、二次污染重等诸多瓶颈。耐盐/嗜盐微生物可在高盐环境下进行正常生理代谢,因此,开发经济、高效、可靠的高盐废水生物处理技术有望成为高盐废水处理的主流方向之一。本文系统综述了耐盐/嗜盐微生物盐溶、胞内小分子相容溶质积累、蛋白质稳定和细胞表面稳定等高渗透压适应策略。由于嗜盐微生物存在生长条件苛刻、功能微生物种类稀缺等问题,因此,耐盐微生物在高盐废水处理的未来应用空间更大。最新研究发现强化调控技术(电、光、磁)可提升微生物的高渗透压适应能力,其中电调控技术或是未来高盐废水生物处理的重点研究方向。     

宏基因组学应用于耐盐酶类及耐盐基因研究的进展

耐盐酶在高盐浓度下仍具备催化活性和稳定性,在高盐食品和海产品加工、洗涤及其它高盐环境生物技术领域被广泛应用;耐盐基因在高盐条件下可以使微生物维持正常功能,获取并研究不同环境中的耐盐基因对揭示微生物的耐盐机制,以及实现其在高盐环境中的定向应用具有的重要意义。宏基因组学避开纯培养技术探知微生物的多样性及其功能,为我们提供了一种发现新基因、开发新的微生物活性物质和研究微生物群落结构及其功能的新技术。文中结合本课题组的研究工作,综述了利用宏基因组学获取耐盐酶类及耐盐基因的策略,同时着重介绍利用宏基因组学从海洋、土壤、胃肠道等环境中获取耐盐酶类及耐盐基因的研究。     

嗜盐菌耐盐机制相关基因的研究进展

嗜盐微生物能够在高盐环境中生存,其耐盐机制一直是微生物学家研究的热点。目前嗜盐微生物耐盐机制的研究主要集中在细胞吸K+排Na+作用、胞内积累小分子相容性溶质及嗜盐酶的氨基酸组成特性三个方面。文章从基因水平综述了嗜盐菌的耐盐机制,并对其在高盐废水处理上的应用进行讨论与展望。     

微生物-矿物相互作用及界面显微分析研究进展

微生物-矿物界面的相互作用贯穿着整个生物浸矿过程,在矿物生物浸出中至关重要,受到微生物的代谢特征、矿物表面结构和物质形态及环境条件的多重交叉影响。研究微生物-矿物界面的相互作用相关的微生物选择性吸附、矿物表面元素形态转化和钝化层、微生物铁硫氧化活性和微生物群落以及胞外物质的组成和性质等的演化,有利于了解微生物-矿物界面作用机制及其关键影响因素和影响机制,从而为优化浸出工艺提供科学的理论依据。达到这些目的,界面的(原位)显微分析手段和技术的进步也至关重要。本文对近些年来上述两方面的研究进行了综述。     

基于基因芯片对微生物基因功能与群落结构分析的硫化矿生物浸出分析

生物冶金技术因具有流程短、成本低、环境友好, 且特别适合处理低品位、复杂、难处理的矿产资源等优点,已经成为研究热点。然而由于缺少高效菌种以及不能对浸矿体系微生物进行定量分析, 难以对浸矿工艺参数和微生物种群进行优化调控, 从而导致硫化矿生物浸出速度慢、浸出率低。随着基因芯片、菌种保存技术的发展, 这些难题在逐一被解决。对近年来针对硫化矿浸出过程微生物的基因功能与群落结构分析的研究进行了概述, 将帮助我们更好地了解基因组学与生物冶金技术结合的重要作用。     

微生物浸出过程中胞外蛋白的作用及其机理研究进展

矿物-微生物-溶液多相界面是硫化矿生物浸出的关键场所,界面微生物胞外多聚物(EPS)关键组分胞外蛋白在生物膜形成、结构稳定和硫化矿溶解等方面起到关键作用。综述了生物浸出过程中EPS关键组分胞外蛋白的研究进展和胞外蛋白现有的研究方法及其对冶金微生物胞外蛋白研究的适用性,展望了浸矿微生物胞外蛋白研究的前景,旨为生物冶金领域研究EPS关键组分胞外蛋白结构及其作用机理提供重要的理论和方法支撑。     

基于基因芯片对微生物基因功能与群落结构分析的硫化矿生物浸出分析

生物冶金技术因具有流程短、成本低、环境友好, 且特别适合处理低品位、复杂、难处理的矿产资源等优点,已经成为研究热点。然而由于缺少高效菌种以及不能对浸矿体系微生物进行定量分析, 难以对浸矿工艺参数和微生物种群进行优化调控, 从而导致硫化矿生物浸出速度慢、浸出率低。随着基因芯片、菌种保存技术的发展, 这些难题在逐一被解决。对近年来针对硫化矿浸出过程微生物的基因功能与群落结构分析的研究进行了概述, 将帮助我们更好地了解基因组学与生物冶金技术结合的重要作用。     

嗜热微生物及在高温生物冶金过程中的应用

嗜热微生物包括中度嗜热微生物和极端嗜热微生物,主要栖息于热泉、火山口、海底热液喷口、高温反应器以及工厂高温废水排放区等自然或人为产生的高温环境中。它们可以生活在40-80°C、甚至更高的温度中,其中有些具备嗜酸性及特殊的代谢类型,在高温生物冶金过程中具有应用潜力。高温生物冶金较传统中温生物冶金更具优势,其能浸出某些难处理矿、解决浸矿过程的钝化问题,以及提高浸出效率等,目前已引起了生物冶金工业的重视。本文概述了应用于生物冶金的主要嗜热微生物的生理特点、耐热机制以及对铁、铜和砷等离子的耐受机制,进一步介绍了嗜热微生物在高温生物冶金中的发展及应用。     

嗜酸嗜热浸矿微生物

随着人们对浸矿菌的研究不断加深,嗜热嗜酸菌的浸矿潜力及在微生物冶金中的作用和地位得到认识,利用嗜热菌对矿石进行高效浸出已成为微生物冶金领域的研究重点。嗜热微生物包括中度嗜热微生物和极端嗜热微生物,主要栖息于热泉、工厂高温废水排放区以及火山口等高温环境中。本综述总结了嗜热浸矿微生物种类,分析了嗜中温菌和极端嗜热菌等嗜酸菌种的生长习性、利用的能源物质、浸矿能力等,并进一步介绍了嗜热嗜酸微生物在高温生物冶金中的发展及应用。     

矿石粒度对西藏玉龙次生硫化铜矿柱浸的影响研究

目的:以西藏玉龙次生硫化铜铜矿为研究对象,考察了该矿石生物浸出的可行性,并且研究了矿石粒度对生物浸出的影响。方法:在小型柱式反应器中,利用实验室在45℃条件下富集获得的一种中等嗜热浸矿富集物进行了小型生物柱浸试验。结果:与常规酸浸相比,中等嗜热浸矿微生物的存在很大幅度地促进了Cu的浸出,可以使Cu的浸出率提高25%,硫酸消耗量减少33%。该矿石经过110天的生物浸出后,5~10 mm粒级矿石最终浸出率高达89%,而15~25 mm粒级矿石最终浸出率为57%,浸出渣相经过XRD分析发现,5~10 mm粒级渣相中出现大量的黄钾铁矾和少量的硫单质。结论:微生物存在可以显著地提高该矿石铜的浸出率,同时降低酸耗。并且随着该矿石粒度的减小,铜的浸出速率显著加快。     

柱式反应器处理黄铜矿过程中等嗜热微生物群落变化

从中国的多个铜矿取样,在45°C条件下富集获得了一种高效的中等嗜热浸矿富集物,探讨了该富集物在柱式反应器中浸出低品位黄铜矿的pH变化以及与Cu2+浸出的关系,并采用限制性片段长度多态性(RFLP)技术分析了微生物的群落结构和种群动态变化规律。结果表明在整个浸出过程中pH变化较为明显,且一直在1.8以上,60 d内回收了13.6%的铜。RFLP结果表明:在初期,嗜铁钩端螺旋菌(Leptospirillum ferriphilum)在浸出前期占有很高比例(81%),随后逐渐降低,至后期只有13%,而耐温氧化硫化杆菌(Sulfobacillus thermotolerans)和喜温硫杆菌(Acidithiobacillus caldus)的比例逐渐升高,在中期分别达到32%和23%;至末期,耐温氧化硫化杆菌达到了79%,成为优势种群。研究加深了对中等嗜热微生物浸矿特性的了解,也为中等嗜热菌处理低品位黄铜矿的工业应用提供了可供借鉴的数据。     

An Immunological Strategy To Monitor In Situ the Phosphate Starvation State in Thiobacillus ferrooxidans

Thiobacillus ferrooxidans is one of the chemolithoautotrophic bacteria important in industrial biomining operations. During the process of ore bioleaching, the microorganisms are subjected to several stressing conditions, including the lack of some essential nutrients, which can affect the rates and yields of bioleaching. When T. ferrooxidans is starved for phosphate, the cells respond by inducing the synthesis of several proteins, some of which are outer membrane proteins of high molecular weight (70,000 to 80,000). These proteins were considered to be potential markers of the phosphate starvation state of these microorganisms. We developed a single-cell immunofluorescence assay that allowed monitoring of the phosphate starvation condition of this biomining microorganism by measuring the increased expression of the surface proteins. In the presence of low levels of arsenate (2 mM), the growth of phosphate-starved T. ferrooxidans cells was greatly inhibited compared to that of control nonstarved cells. Therefore, the determination of the phosphorus nutritional state is particularly relevant when arsenic compounds are solubilized during the bioleaching of different ores.     

Bioleaching of Different Pyrites and Sphalerite in the Presence of Graphite

In this research work the effect of pyrite type and graphite on the pyrite and sphalerite dissolution rate was investigated, using a mixed culture of moderately thermophilic microorganisms. Two samples of: fine granular surface pyrite and crystalline euhedral pyrite were prepared from black shale and copper porphyry deposits, respectively. Results indicated that granular surface pyrite dissolution rate and Fe(III) concentration are significantly higher than those of crystalline euhedral pyrite. As a result, higher Zn extraction improvement was observed in the presence of granular surface pyrite. Addition of graphite to the experiments enhanced the microorganism population in leaching solution and accelerated crystalline euhedral pyrite and sphalerite bioleaching rate. Using graphite in the experiments resulted in catalytic effect of crystalline pyrite and sphalerite, in which, with graphite, the Fe extraction increased from 25.57% to 59.84% and Zn extraction was improved from 22.17% to 53.37%, for 28 days of bioleaching. The catalytic effect of graphite on crystalline euhedral pyrite and also sphalerite bioleaching could be attributed to the rising of the microorganism population or galvanic interaction in which graphite acted as the cathode and accelerated the anodic dissolution of pyrite and sphalerite.     

The use of genetic probes to detect microorganisms in biomining operations

Summary Microorganisms are currently used for the recovery of copper from mining dumps of low-grade ore. One of the most important microorganisms involved in copper-solubilization isThiobacillus ferrooxidans, although many other microbial genera are also thought to be implicated. A mining dump poses some special problems for the industrial microbiologist because it represents a non-sterile and heterogeneous substrate. Consequently, to enhance our knowledge of the role of microorganisms in metal recovery we must identify the indigenous microorganisms and understand their respective contributions to the process. In addition, when a superior strain of microorganism is developed in the laboratory, by genetic engineering or by other means, we must have a method to evaluate the maintenance of such a strain in the mining dump. In this paper, we describe DNA homology studies, using dot blot and Southern blot analysis of hybridizations of both whole genomic DNA and cloned DNA sequences, to identify and enumerate several bioleaching microorganisms. We demonstrate that it is possible to identify different species of microorganisms and, in one case, to discriminate between different strains of a single species. It is also possible to identify and quantitate certain species in a mixed culture. DNA hybridization analysis has several advantages over the more conventional bacteriological methods of identification, especially in a complex bioleaching situation.     

BBProF: An Asynchronous Application Server for Rapid Identification of Proteins Associated with Bacterial Bioleaching

Recovery of metal value, especially from low-grade ores and overburden minerals using acidophilic bacteria through the process of bioleaching is an environmentally benign and commercially scalable biotechnology. In recent years, while the “OMICS” landscape has been witnessing extensive application of computational tools to understand and interpret global biological sequence data, a dedicated bioinformatic server for analysis of bacterial information in the context of its bioleaching ability is not available. We have developed an on-line Bacterial Bioleaching Protein Finder (BBProF) System, which rapidly identifies novel proteins involved in a bacterial bioleaching process and also performs phylogenetic analysis of 16S rRNA genes. BBProF uses the features of Asynchronous Java Script and XML (AJAX) to provide an efficient and fast user experience with minimal requirement of network bandwidth. In the input module the server accepts any bacterial or archaeal complete genome sequence in RAW format and provides a list of proteins involved in the microbial leaching process. BBProF web server is integrated with the European Bioinformatics Institute (EBI) web services such as BLAST for homology search and InterProScan for functional characterization of output protein sequences. Studying evolutionary relationship of bacterial strains of interest using Muscle and ClustalW2 phylogeny web services from EBI is another key feature of our server, where 16S rRNA gene sequences are considered as input through a JQUERY interface along with the sequences present in the BBProF database library. Complete genome sequences of 24 bioleaching microorganism characterized by genomic and physiological study in the laboratory and their respective 16S rRNA gene sequences were stored in the database of the BBProF library. To our knowledge BBProF is the first integrated bioinformatic web server that demonstrates its utility in identifying potential bioleaching bacteria. We hope that the server facilitate ongoing comparative genomic studies on of bioleaching microorganisms and also assist in identification and design of novel microbial consortia that are optimally efficient bioleaching agents.     

Non‐homogeneous biofilm modeling applied to bioleaching processes

A two‐dimensional non‐homogeneous biofilm model is proposed for the first time to study chemical and biochemical reactions at the microorganism scale applied to biological metal leaching from mineral ores. The spatial and temporal relation between these reactions, microorganism growth and the morphological changes of the biofilm caused by solid inorganic precipitate formation were studied using this model. The model considers diffusion limitations due to accumulation of inorganic particles over the mineral substratum, and allows the study of the effect of discrete phases on chemical and microbiological mineral solubilization. The particle‐based modeling strategy allowed representation of contact reactions between the microorganisms and the insoluble precipitates, such as those required for sulfur attack and solubilization. Time‐dependent simulations of chemical chalcopyrite leaching showed that chalcopyrite passivation occurs only when an impervious solid layer is formed on the mineral surface. This mineral layer hinders the diffusion of one kinetically determinant mineral‐attacking chemical species through a nearly irreversible chemical mechanism. Simulations with iron and sulfur oxidizing microorganisms revealed that chemolithoautotrophic biofilms are able to delay passivation onset by formation of corrosion pits and increase of the solid layer porosity through sulfur dissolution. The model results also show that the observed flat morphology of bioleaching biofilms is favored preferentially at low iron concentrations due to preferential growth at the biofilm edge on the surface of sulfur‐forming minerals. Flat biofilms can also be advantageous for chalcopyrite bioleaching because they tend to favor sulfur dissolution over iron oxidation. The adopted modeling strategy is of great interest for the numerical representation of heterogeneous biofilm systems including abiotic solid particles. Biotechnol. Bioeng. 2010;106: 660–676. © 2010 Wiley Periodicals, Inc.     

烟叶微生物及其在烟叶发酵和醇化中的作用研究进展

微生物在烟叶发酵和醇化过程中具有十分重要的作用。本文综述了烟叶微生物概况及其在烟叶发酵和醇化中的应用和研究进展。主要介绍了烟叶微生物的区系划分、烟叶发酵和醇化过程中微生物动态变化以及外源添加微生物的应用方法。阐述了微生物在缩短烟叶发酵和醇化周期、改善烟叶品质、降低烟叶有害物质和提高烟叶安全性等方面的研究应用成果。最后,对该领域今后的研究方向提出了展望。     

Bioleaching of Heavy Metals from Textile Sludge by Indigenous Sulfur-and-Iron-Oxidizing Microorganisms Using Elemental Sulfur and Ferrous Sulfate as Energy Sources: A Comparative Study

The present study was undertaken to investigate the potential of enriched indigenous sulfur-and-iron-oxidizing microorganisms in the bioleaching of Cu, Ni, Zn and Fe from textile sludges by using elemental sulfur and ferrous sulfate (FS), respectively, as an energy source under batch conditions. The experiments were performed with three different textile sludges (S1, S2 and S3) at initial neutral pH of the sludges procured from different parts of the country i.e., UP, Haryana and Punjab. The three sludges used were not only procured from different parts of the country but also differ in physiochemical characteristics. The extent of heavy metals solubilization in each sludge was found to be different using sulfur- and iron-oxidizing microorganisms. The results of the study indicate that sulfur-oxidizing microorganisms were found more efficient in the bioleaching process, irrespective of any sludge. The use of sulfur-oxidizing microorganisms led to higher solubilization of heavy metals and after 7 days of bioleaching about 84–96% Cu, 64–78% Ni, 81–92% Zn and 74–88% Fe were removed compared to 62–73% Cu, 62–66% Ni, 74–78% Zn and 70–78% Fe using iron-oxidizing microorganisms. This study had shown the feasibility of applying the bioleaching process to textile sludge contaminated with heavy metals. The results of the present study indicate that the bioleached sludge would be safer for land application.