嗜酸硫杆菌属硫氧化系统研究进展

硫化矿的酸溶解和化学氧化过程中(H 和Fe3 作用下,金属硫化矿中分解),伴随着硫元素转变成多聚硫S8或硫代硫酸盐的过程。对嗜酸硫杆菌属硫氧化过程的研究表明,胞外环状多聚硫S8可能通过细胞外膜蛋白巯基活化成线状-SnH后,被转运到细胞周质区域,进而被硫加双氧酶氧化成SO32-,活化过程中同时生成少量H2S;这些酶促反应不需要辅助因子参与,不释放电子。胞外硫代硫酸盐通过未知途径进入细胞周质。细胞周质中的SO32-主要经由亚硫酸-受体氧化还原酶氧化成SO42-,S2O32-可能经由硫代硫酸盐-辅酶Q氧化还原酶、硫代硫酸盐脱氢酶、连四硫酸盐水解酶等氧化为硫酸,少量H2S则经由硫化物-辅酶Q氧化还原酶氧化为多聚硫,后者再经由SO32-和S2O32-氧化生成最后产物SO42-。这些生物氧化过程释放的电子进入呼吸链参与产生细菌生长代谢所需的能量。然而,关于A.ferrooxidans硫氧化系统中各种硫化合物的酶催化氧化机制的研究仍很缺乏,胞内外硫化合物的转运机制、是否存在胞外酶催化氧化等仍然有待解决。另外,硫的型态和价态、酶催化反应的细胞微区域以及硫氧化系统中一些关键酶的分离及其表达基因的鉴定等问题都还有待进一步研究。基于对这些事实的分析,提出了一个嗜酸硫杆菌属硫氧化系统的模型。     

一株脱氮硫杆菌的筛选及其脱氮除硫性能分析

利用人工模拟酸性环境,从定期浇注HCl的土壤中筛选出一株脱氮硫杆菌T1菌株,并对其生长特性以及pH、盐度等理化因素对其脱氮除硫性能的影响进行了研究。结果表明,该菌株最适生长pH为7.02,最适脱氮pH为7.0;培养基中NaCl含量低于1.5%时,其脱氮能力没明显变化;与硫酸盐还原菌混菌培养能将H2S氧化为SO42-,从而明显抑制H2S的产生。在液体静置混菌培养过程中,在培养开始后的24 h内,SO42-生成速率最大(11.21 mg/(L·h)),随后不断降低。该菌不仅适用于不同pH、盐度废水的生物处理,还可以与硫酸盐还原菌混合添加到厌氧消化池中以减少硫化物的形成,从而减轻后者对污水处理系统中的金属设备和管道的腐蚀作用以及硫化氢对大气的污染。     

硫氧化细菌的种类及硫氧化途径的研究进展

硫,作为生物必需的大量营养元素之一,参与了细胞的能量代谢与蛋白质、维生素和抗生素等物质代谢。自然界中,硫以多种化学形态存在,包括单质硫、还原性硫化物、硫酸盐和含硫有机物。硫氧化是硫元素生物地球化学循环的重要组成部分,通常是指单质硫或还原性硫化物被微生物氧化的过程。硫氧化细菌种类繁多,其硫氧化相关基因、酶和途径也多种多样。近几年,相关方面的研究已取得很多进展,但在不同层面仍存在一些尚未解决的科学问题。本文主要围绕硫氧化细菌的种类及硫氧化途径的研究进展进行了综述。     

一株异养脱硫反硝化菌株的筛选及其生物脱硫脱氮特性研究

【目的】从生物脱硫脱氮EGSB-DSR反应器的污泥中分离筛选出具有生物脱硫脱氮特性的细菌,并对其生物脱硫脱氮的性能进行研究。【方法】采用Hungate厌氧滚管技术筛选功能微生物,从稳定运行的生物脱硫脱氮EGSB-DSR反应器的污泥中分离筛选出一株高效的生物脱硫脱氮细菌A2。【结果】经过16S rRNA基因序列鉴定,菌株A2为固氮弧菌属(Azoarcus sp.)。其典型特征为能够以有机碳作为电子供体,将亚硝酸盐或者硝酸盐转化为氮气的同时还能将硫化物氧化为硫单质。因此具备了高效同步代谢有机碳、NO3–和S2–的特征。这是首次关于固氮弧菌属能够进行反硝化脱硫的相关报道。对菌株A2的生物脱硫脱氮能力的分析表明,在硫化物S2–浓度200 mg/L,NO3?浓度87.5 mg/L,乙酸根离子浓度200 mg/L的条件下,菌株A2在20 h内完成对碳、氮、硫的脱除。菌株对于碳、氮去除率均达到99%,对于硫的去除率达到95%。【结论】结果表明固氮弧菌属A2具有高效的生物脱硫脱氮功能,将有望成为强化生物脱硫脱氮工艺的潜在微生物资源。     

硫氧化菌种脱除硫化物生成单质硫限制性因素优化

【目的】针对硫氧化菌种较为特殊的生化特性,优选其氧化硫化物生成单质硫过程的相关限制性因素,以提高该类菌种生成单质硫效率。【方法】采用一株典型脱硫菌Thermithiobacillus tepidarius JNU-2(T.tepidarius JNU-2)氧化硫化物生成单质硫。研究该菌株在以Na2S2O3为能源底物时的培养特性和脱硫性能,并结合单因素实验对菌株氧化硫化物生成单质硫的限制性因素进行优选。【结果】T.tepidarius JNU-2在以Na2S2O3为唯一能源底物培养时的μmax为0.207 h-1,最终生物量为4.0×106 cells/m L。98%的Na2S2O3在24 h时被消耗殆尽,此时单质硫产量达到最大值为0.8 g/L。随后单质硫逐渐被氧化利用,最终稳定在0.2 g/L。经过对该过程主要限制性因素进行单因素实验优化,确定最佳碳氮源、Mg SO4、Fe SO4和能源底物条件分别为:CO2、NH4Cl0.5 g/L、Mg SO4 0.5 g/L、Fe SO4 0.1 g/L和Na2S2O3 15.0 g/L。优化后的氧化Na2S2O3生成单质硫过程的最大生物量可达4.8×106 cells/m L,单质硫产量提升至1.14 g/L。相较于未优化之前,单质硫的产量提高了42.5%。【结论】优化该过程主要限制性因素可有效提高化能自养型T.tepidarius JNU-2氧化硫化物生成单质硫效率。     

硫代硫酸盐氧化菌TX的分离、鉴定及其生物学特性

从聚硫橡胶废水处理系统中分离到一株硫代硫酸盐氧化细菌TX.根据其形态学特征、生理特征和16S rRNA基因序列相似性分析,将该菌株初步鉴定为盐生硫杆菌属(Halothiobacillus sp.)(GenBank登录号为EU871645).该菌株能利用硫代硫酸盐、单质硫、连四硫酸盐、硫化物或亚硫酸盐为唯一能源进行自养生长,不能利用葡萄糖、蔗糖、果糖、乳糖、麦芽糖或酵母粉进行异养生长,为专性化能无机自养型硫杆菌.在以硫代硫酸钠为唯一能源的培养基中其最适生长温度为30℃～35℃,最适起始pH值为3.0～5.0.在矿物盐培养基中,硫代硫酸盐最终被氧化成硫酸,造成培养基pH持续下降.在摇瓶分批培养和硫胶废水处理过程中均检测到连四硫酸盐的积累,表明该菌株主要通过连四硫酸盐途径或"S4I"途径进行硫代硫酸盐的生物氧化.     

双阳极室甲烷微生物燃料电池同步脱氮除硫性能及微生物群落分析

【背景】甲烷厌氧氧化(anaerobic oxidation of methane, AOM)包含反硝化型甲烷厌氧氧化和硫酸盐还原型甲烷厌氧氧化。目前,人们向水体中排放过量的含氮及含硫污染物,引起了严重的环境污染和生态破坏。【目的】利用甲烷厌氧氧化微生物燃料电池(microbial fuel cell, MFC)研究同步脱氮除硫耦合反应机理及反应过程中微生物的多样性信息。【方法】构建了3个微生物燃料电池(N-S-MFC、N-MFC、S-MFC),以甲烷作为唯一碳源,探究其同步脱氮除硫性能,并采用16S rRNA基因高通量测序技术对微生物群落结构进行分析。【结果】N-S-MFC中硝酸盐和硫酸盐的去除率分别为90.91%和18.46%。阳极室中微生物的相对丰度提高,与反硝化及硫酸盐还原菌相关的微生物大量富集,如门水平上拟杆菌门(Bacteroidota)、厚壁菌门(Firmicutes)和脱硫杆菌门(Desulfobacterota),同时属水平上Methylobacterium＿Methylorubrum、Methylocaldum、Methylomonas等常见的甲烷氧化菌增多。【结论...     

盐分对生物脱氮工艺中硝化反应的影响与机理

高盐废水来源广泛,在利用生物脱氮法处理高盐含氮废水时,盐分会对生物脱氮产生抑制作用.硝化反应是生物脱氮工艺中的关键过程,研究盐分对硝化反应的影响机理具有重要意义.本文概述了盐分对废水生物脱氮过程中硝化反应影响的研究进展,总结了盐胁迫对好氧氨氧化过程、亚硝酸盐氧化过程中硝化效率和反应特性的影响规律,并分析了盐分对硝化微生物细胞形态、生物絮体结构和胞外聚合物特性变化以及菌群结构的影响,系统阐述了盐胁迫下的硝化反应机理,为高盐分高铵氮废水生物脱氮工艺设计提供理论指导.
     

包埋法固定化对硫氧化微生物菌群结构和功能的影响

【目的】为探讨包埋法固定化过程对硫氧化菌群硫化物去除能力及菌群微生物群落结构的影响,【方法】以聚乙烯醇-海藻酸钠-活性炭为载体,对硫氧化菌群进行了固定化,并采用富含硫化物的无机盐培养基,对比固定化与非固定化硫氧化菌群对硫化物的氧化去除能力。同时,利用PCR-DGGE技术,探讨硫氧化菌群在固定化前后以及在硫化物氧化去除过程中微生物群落结构变化。【结果】在对硫氧化菌群进行固定化之后,12 h之内对硫化物的最大去除能力从1000 mg/L下降为600 mg/L。硫氧化菌群的微生物群落结构发生了明显变化,但菌群中的硫氧化菌Catenococcus thiocycli未受影响,硫氧化菌Thioclava pacifica在菌群中的地位反而得到了强化。【结论】受制于底物在载体材料中的扩散迁移效率,硫氧化菌群对硫化物的氧化去除能力在固定化之后有所下降。由于不同微生物对固定化形成的微环境的适应能力以及对载体附着能力的不同,固定化对硫氧化菌群的微生物群落结构产生较大影响。     

粪产碱杆菌的分离鉴定及其生物转化作用

【背景】硫化氢(H2S)作为畜牧生产过程中释放的一种有毒有害气体,严重危害畜禽和人类的健康,因此降解硫化氢特别是生物氧化法转化硫化氢已成为当前研究热点。【目的】筛选高效硫氧化菌株并研究其生物转化作用。【方法】以长春市某养鸡场采集的新鲜粪便为材料,分离鉴定硫氧化菌株。采用单因素分析法优化其生长条件,研究生物转化效率,检测soxY、soxZ基因m RNA表达水平。【结果】获得一株高效硫氧化菌株JF9,经鉴定为粪产碱杆菌。最佳生长条件:底物浓度0.5 g/L,温度35°C,初始pH 7.0,在此条件下Na2S去除率达94%以上。菌株JF9存在soxY和soxZ基因,其转录水平在硫源诱导前后差异显著(P0.05)。【结论】分离得到的粪产碱杆菌具有良好的硫化物转化能力,脱硫过程中硫氧化基因高效表达。     

Microbial control of the production of hydrogen sulfide by sulfate-reducing bacteria

A sulfide-resistant ctrain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium or in Berea sandstone cores. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. These data suggest that strain F would be effective in controlling sulfide production in oil reservoirs and other environments.     

Control of a Thiobacillus denitrificans bioreactor using machine vision

A PC-based machine vision system has been used to continuously monitor changes in biomass concentration and to control the undesirable production of colloidal elemental sulfer (a reactor upset condition due to an excessive concentration of inhibitory sulfide substrate) in a bioreactor containing Thiobacillus denitrificans. A field of view of a video camera was established which contained regions of different background lighting. Mean values of the distribution of red, green, and blue intensity components within corresponding regions of a digital image image captured from the camera were used to monitr color changes associated with changes in biomass concentration, and to determine if the reactor was in an upset condition. The ration of red to blue intensity components was an important parameter in detecting the formatin of an elemental sulfur precipitant. Using a stepper motor-driven pressure regulator, intelligent process control was performed by altering the hydrogen sulfide feed flow rate setpoint on the vision system measurements.     

Characterization of a novel biocatalyst system for sulfide oxidation

It has been demonstrated that an enrichment culture dominated by Thiomicrospira sp. CVO may be cultured on H2S(g) as an energy source under sulfide-limiting conditions in suspended culture with nitrate as the electron acceptor. Hydrogen sulfide (10,000 ppmv) was completely removed from the feed gas and oxidized to sulfate in <3 s of gas-liquid contacting time. Maximum loading of the biomass for sulfide oxidation was observed to be 5.8 mmol H2S/h-g biomass protein, comparable to that reported previously for Thiobacillus denitrificans under similar conditions. However, the enrichment culture was shown to be more tolerant of extremes in pH and elevated temperature than T. denitrificans. Coupled with a reported tolerance of CVO for up to 10% NaCl, these observations suggest that a CVO-based culture is potentially a more robust biocatalyst system for sulfide oxidation than cultures based on Thiobacilli.     

Technological aspects of the microbial treatment of sulfide-rich wastewaters: A case study

Thiobacillus denitrificans has been shown to be an effective biocatalyst for the treatment of a variety of sulfide-laden waste streams including sour water, sour gases, and refinery spent-sulfidic caustics. The term 'sour' originated in the petroleum industry to describe a waste contaminated with hydrogen sulfide or salts of sulfide and bisulfide. The microbial treatment of sour waste streams resulting from the production or refining of natural gas and crude oil have been investigated in this laboratory for many years. The application of this technology to the treatment of sour wastes on a commercially useful scale has presented several technical barriers including substrate inhibition (sulfide), product inhibition (sulfate), the need for septic operation, biomass recycle and recovery, mixed waste issues, and the need for large-scale cultivation of the organism for process startup. The removal of these barriers through process improvements are discussed in terms of a case study of the full-scale treatment of sulfide-rich wastewater. The ability of T. denitrificans to deodorize and detoxify an oil-field produced water containing sulfides was evaluated under full-scale field conditions at Amoco Production Co. Salt Creek Field in Midwest, WY. More than 800 m³/d of produced water containing 100 mg/L sulfide and total dissolved solids of 4800 mg/L were successfully biotreated in an earthen pit (3000 m³) over a six-month period. Complete removal of sulfides and elimination of associated odors were observed. The system could be upset by severe hydraulic disturbances; however, the system recovered rapidly when normal influent flow rates were restored.     

Coexistence of aerobic chemotrophic and anaerobic phototrophic sulfur bacteria under oxygen limitation

Abstract: The aerobic chemotrophic sulfur bacterium Thiobacillus thioparus T5 and the anaerobic phototrophic sulfur bacterium Thiocapsa roseopersicina M1 were co-cultured in continuously illuminated chemostats at a dilution rate of 0.05 h⁻¹. Sulfide was the only externally supplied electron donor, and oxygen and carbon dioxide served as electron acceptor and carbon source, respectively. Steady states were obtained with oxygen supplies ranging from non-limiting amounts (1.6 mol O₂ per mol sulfide, resulting in sulfide limitation) to severe limitation (0.65 mol O₂ per mol sulfide). Under sulfide limitation Thiocapsa was competitively excluded by Thiobacillus and washed out. Oxygen/sulfide ratios between 0.65 and 1.6 resulted in stable coexistence. It could be deduced that virtually all sulfide was oxidized by Thiobacillus . The present experiments showed that Thiocapsa is able to grow phototrophically on the partially oxidized products of Thiobacillus . In pure Thiobacillus cultures in steady state extracellular zerovalent sulfur accumulated, in contrast to mixed cultures. This suggests that a soluble form of sulfur at the oxidation state of elemental sulfur is formed by Thiobacillus as intermediate. As a result, under oxygen limitation colorless sulfur bacteria and purple sulfur bacteria do not competitively exclude each other but can coexist. It was shown that its ability to use partially oxidized sulfur compounds, formed under oxygen limiting conditions by Thiobacillus , helps explain the bloom formation of Thiocapsa in marine microbial mats.     

排硫硫杆菌D6中硫化氢脱氢酶的纯化及性质

从烟气生物脱硫系统的好氧产硫磁性稳态流化床反应器中,经反复纯化分离出脱硫优势菌排硫硫杆菌菌株D6,采用四步工艺纯化出膜结合型硫化氢脱氢酶。SDS-PAGE测定显示其由α1β1亚基组成,光谱分析表明含有1 mol FAD/mol酶,血红素染色揭示小亚基上结合有1 mol血红素c/mol酶,该酶属于氧还蛋白家族。该酶的最适pH为8.6,对马心细胞色素c和硫化物的表观Km分别为2.5μmol/L和6.1μmol/L,反应计量实验表明其氧化产物为元素硫。硫化氢脱氢酶受到硫和亚硫酸盐的抑制,100μmol/L的氰化钾对该酶抑制率达72%。     

Importance of Hydrogen Sulfide, Thiosulfate, and Methylmercaptan for Growth of Thiobacilli during Simulation of Concrete Corrosion

Biogenic sulfuric acid corrosion of concrete surfaces caused by thiobacilli was reproduced in simulation experiments. At 9 months after inoculation with thiobacilli, concrete blocks were severely corroded. The sulfur compounds hydrogen sulfide, thiosulfate, and methylmercaptan were tested for their corrosive action. With hydrogen sulfide, severe corrosion was noted. The flora was dominated by Thiobacillus thiooxidans. Thiosulfate led to medium corrosion and a dominance of Thiobacillus neapolitanus and Thiobacillus intermedius. Methylmercaptan resulted in negligible corrosion. A flora of heterotrophs and fungi grew on the blocks. This result implies that methylmercaptan cannot be degraded by thiobacilli.     

脱氮硫杆菌生长特性及其对SRB生长的影响

由土壤中分离得到一株自养型的脱氮硫杆菌(Thiobacillus denitrigioans,硫杆菌属,硫杆菌科,革兰氏阴性化能自养细菌),该菌株的最佳生长pH为7．0。将此菌株与硫酸盐还原菌(Sulfate Reducing Bacteria,SRB,脱硫弧菌属,革兰氏阴性厌氧细菌)混合培养,测定SRB的菌量变化,结果表明,脱氮硫杆菌的生长抑制了硫酸盐还原菌的生长,降低了SRB的腐蚀性的代谢产物硫化物的浓度,腐蚀速率降低,有利于防治SRB引起的微生物腐蚀。     

Purification of Thiobacillus denitrificans siroheme sulfite reductase and investigation of some molecular and catalytic properties.

A siroheme-containing sulfite reductase was isolated from Thiobacillus denitrificans, purified to an electrophoretically homogenous state, and investigated with regard to some of its molecular and catalytic properties. The enzyme was a tetramer with a molecular weight of 160 000, consisting of two types of subunits arranged to an alpha 2 beta 2-structure. The molecular weight of the alpha-subunit was 38 000, that of the beta-subunit 43 000. As prosthetic groups siroheme and Fe/S groupings could be detected. The absorption spectrum showed maxima at 273 nm, 393 nm, and 594 nm; the molar extinction coefficient at these wavelengths were 280, 181, and 60 . 10(3) cm2 . mmol-1, respectively. With reduced viologen dyes the enzyme reduced sulfite to sulfide, thiosulfate and trithionate. In many properties T. denitrificans sulfite reductase closely resembled desulfoviridin, the dissimilatory sulfite reductase of Dssulfovibrio species. It is proposed that the physiological function of this enzyme is not to reduce but rather to form sulfite from reduced sulfur compounds in the course of dissimilatory sulfur oxidation in T. denitrificans.     

Oxidation of hydrogen sulfide by Thiobacillus denitrificans: desulfurization of natural gas

It has been demonstrated that Thiobacillus denitrificans may be readily cultivated anaerobically in batch reactors on H(2)S (g) under sulfide-limiting conditions. Under these conditions sulfide concentrations in the culture medium were less than 1 muM, resulting in very low concentrations of H(2)S in the reactor outlet gas. The stoichiometry of the reaction was determined, and stable reactor operation was demonstrated at reactor loadings as high as 4-5 mmol H(2)S oxidized/h g biomass. Maximum loading was estimated at 5.4-7.6 mmol H(2)S/h g biomass under the conditions employed in this study. Indicators of reactor upset were determined and recovery from upset conditions demonstrated. Barotolerance of T. denitrificans to 12.5 MPa as well as a relative insensitivity to pressurization-depressurization cycles were also demonstrated. T. denitrificans was observed to be very sensitive to CH(3)SH but relatively tolerant of CS(2), COS, and CH(3)SCH(3).