云南保山盆地生物气生成模拟实验及生物气资源预测

根据有机地球化学、微生物学实验方法,对云南保山盆地生物气源岩进行了研究。鉴定了主要气夺中产甲烷细菌等厌氧微生物分布,求取了不同温度下生化甲烷产率,揭示了盆地生物气生成特征,从而建立了盆地生物气生成模式和评价依据,结合盆地地质背景及有机地球化学特征,进行了盆地生物气生成量预测,指出了有利勘探区。     

褐煤中天然产甲烷菌富集培养与生物气产出模拟

采用厌氧培养方法,在云南省昭通褐煤样品中成功地培养富集了活性厌氧细菌,并进一步开展了为期60天的生物气生成模拟实验,分析了生物气的生成规律、物质组成和成因机制。结果揭示：3件褐煤样品中均有活性厌氧细菌存在,以纤维素分解菌为主,活性硫酸盐还原菌极其微少,说明昭通盆地褐煤层具有较强还原性的生化环境,有利于产甲烷菌的繁盛;生物气的生成经历了生气量缓慢增长、显著增高、趋于减缓三个阶段,表明产甲烷菌在经历了第一阶段缓慢繁殖后,其数量和活性在第二阶段达到较高水平;3件煤样生气量和生气历程存在一定差别的原因,可能在于原煤中活性产甲烷菌数量以及显微组分组成方面存在差异,褐煤生物气生成过程至少存在两个以上的生气高峰阶段。模拟实验中产生的生物气几乎全部由CH4和CO2组成,且CH4占主要部分,几乎没有检测到重烃气。甲烷气体δ13C1和δD的平均值均处于生物甲烷碳、氢同位素组成的正常分布范围。     

铁氧化物对有机质厌氧产甲烷过程的影响及其机制

甲烷(CH?)不仅是自然界产生的重要温室气体,也是人类已经推广利用的可再生能源之一.作为自然界广泛存在的矿物,铁氧化物同厌氧微生物的交互作用对产甲烷过程具有显著的影响.主要针对不同铁氧化物-厌氧微生物体系内的产甲烷效率,铁氧化物及微生物群落演化,铁氧化物的作用机制等进行总结分析.铁氧化物在微生物的作用下会发生溶解、还原并可能产生新的矿物.而铁氧化物的直接和间接影响微生物群组成,进而影响产甲烷过程,主要体现在4个方面:(1)铁氧化物溶解及生物还原产生的Fe~(3+)/Fe~(2+)影响微生物活性和体系氧化还原电位;(2)铁还原菌和产甲烷菌竞争产甲烷基质;(3)铁氧化物对产甲烷菌的直接抑制毒性;(4)具有导电性能的铁氧化物可以作为电子传递媒介促进铁还原菌或脂肪酸氧化菌与产甲烷菌之间的直接电子传递过程.最后,探讨了铁氧化物促进产甲烷过程尚需解决的主要问题及研究趋势,以期推动铁氧化物-厌氧微生物交互作用及其环境效应方面的研究工作.     

海洋极端环境微生物活动与油气资源关系

为了弄清海洋极端环境下微生物参与油气资源形成和演化的潜在机制, 进行了现代海洋热泉和冷泉等环境中微生物类型分析和生物量估算, 探讨了极端微生物活动和油气资源的潜在关系.认为海洋极端环境下微生物类型主要为细菌和古细菌, 热泉微生物群落主要为异养发酵菌、硫酸盐还原菌、产甲烷菌等; 冷泉微生物群落主要为ANME-2族的厌氧甲烷氧化古细菌、硫酸盐还原细菌和ANME-1族厌氧甲烷氧化古菌.这些极端微生物利用CH₄和H₂S等气体进行能量固定, 有较高的生物丰度和较低的分异度, 具有垂向和水平分带性, 并能营生一套独特的宏体生物.极端微生物活动直接和间接地参与了油气资源的形成和改造, 示踪海底油气资源的变迁.对于探索地球早期海洋微生物活动与油气资源形成, 寻找地史时期或华南地史早期烃源岩具有重要理论和实践指导意义.      

海洋天然气水合物勘查和识别新技术:地质微生物技术

当前国内外海洋天然气水合物勘查和评价发展趋势要求有更多具有精细探测和评价功能的技术,这给地质微生物水合物探测技术的研发和应用提出了需求和挑战。简要介绍了当前水合物成藏或沉积环境研究中所涉及的主要微生物类别及其主要关系,它们绝大多数是适应海底深部低温高压环境的厌氧极端生物。其中重要类群是为天然气提供气源的产甲烷古生菌、参与甲烷厌氧氧化过程的甲烷氧化古生菌和硫酸盐还原细菌。介绍了国内外几个地质微生物探测技术的实例,包括历史悠久的"微生物油气勘探"技术、近十年来发展起来的微生物计数法、群落结构和标志类别法;另外,对新露头角的微生物生物标志物法等其他方法也给予简要介绍。     

南海北部九龙甲烷礁邻区沉积物层中垂向细菌群落结构特征研究

本研究应用微生物16S rRNA-DGGE和T-RFLP技术,结合环境参数,对我国天然气水合物潜在区南海九龙甲烷礁附近973-4柱状样沉积物中3个层位12个不同深度(表层20 cm至382 cm,中层552 cm至796 cm,深层862 cm至1 196 cm)细菌群落结构及其分布进行了对比研究.其中T-RFLP实验表明,细菌丰度、香农指数和均匀度变化趋势相同,由深层到716 cm处先降后升,中层716 cm深度范围处微生物群落丰度、均匀度、香农指数相对较高,716 cm至表层先降后升.DGGE图谱和T-RFLP色谱峰聚类分析表明:表层20 cm至192 cm相似性较高,表层236 cm至382 cm与深层1 082 cm、1 196 cm群落结构相似性较高,但中层沉积物中微生物群落结构与表层及深层均有较大差异.环境参数表明中层甲烷含量较高,推测甲烷是影响微生物群落结构差异的主要因素之一.T-RFLP色谱峰与微生物数据库比对及DGGE条带测序也表明了:本区变形杆菌(Proteobacteria)为优势菌群,其中α-、γ-、δ-变形杆菌(Proteobacteria)为主要的细菌亚群,其他细菌包括放线菌(Actinobacteria)、厚壁菌门(Firmicutes)、绿弯菌门(Chloroflexi)为次优势菌群.甲烷含量较高的中层,甲烷氧化菌(Methanotrophs),硫还原菌(Sulfate-reducing bacteria)等与甲烷密切相关的细菌均有被检测到,表明该区域存在与天然气水合物的分解释放相关的微生物群落.     

煤层气生物工程关键预处理技术及其作用机制评述

煤层气生物工程是以实现煤炭资源清洁化利用和煤层气资源强化采出为目标的一项新兴技术。为探究煤层气生物工程关键预处理技术的特点、生烃潜力及其作用机制,对不同预处理技术进行了归纳与总结,并按煤(有机质)与菌(微生物)的作用方式将预处理技术分为菌群优化与改良、煤的溶解与氧化、生物刺激与协同3种类型,通过不同预处理技术下微生物降解煤生成甲烷能力的强弱关系的比较,认为不同预处理技术均对生物甲烷具有增产作用,其中,菌群优化与改良技术增产效果最高,达到428.6%~2 335.2%(平均1025.4%),是通过提高产甲烷菌丰度或提升菌群数量来达到增产甲烷的效果,适用于烟煤储层及微量元素充足条件;其次是煤的溶解与氧化技术,甲烷增幅达17.6%~733.3%(平均223.4%),作用机制是增加生物酶水解作用位点、降低煤分子间作用力、脱落含氧官能团、降低煤结晶度和破坏煤的芳香结构使煤更容易被微生物利用,适用于高阶煤储层及低孔低渗条件;生物刺激与协同技术,甲烷增幅达28.3%~620.5%(平均148.6%),是利用不同方式刺激微生物体内的生物酶活性和增加菌?煤接触面积来增产生物甲烷,适用于褐煤储层及胍胶压裂条件。研究结果对于丰富煤层气生物工程基础理论和指导现场工程应用均具有重要的科学意义。      

海洋环境中乙烷和丙烷的分布及生物转化

海洋沉积物中蕴含着大量以甲烷（CH₄）、乙烷（C₂H₆）和丙烷（C₃H₈）为主要成分的烷烃化合物,与甲烷类似,乙烷与丙烷也是重要的温室气体。水合物分解和油气渗漏会释放这些烷烃化合物到海水及大气中,对海洋生态环境及全球气候产生重要影响。海洋环境中的微生物对烷烃的氧化作用有效降低了海洋烷烃气体的排放通量。系统综述了海洋环境中乙烷和丙烷的分布及生物转化机制的最新研究进展,归纳出以下认识：（1）海水中乙烷与丙烷的分布特征明显,主要受到水文、化学及生物等环境参数的影响;（2）海洋环境中乙烷与丙烷的生物来源主要有海水中浮游植物生产释放和沉积物中厌氧微生物生成,产甲烷菌可以利用多种底物生成乙烷与丙烷;（3）乙烷和丙烷的好氧氧化主要由烷烃氧化菌完成,并且该过程中伴随一定程度的碳氢同位素分馏;（4）沉积物中乙烷与丙烷的厌氧氧化通常与硫酸盐还原耦合,目前已对参与氧化乙烷与丙烷的硫酸盐还原菌及厌氧氧化机制有了初步认识。总结和回顾了海洋环境中乙烷和丙烷的来源、分布及微生物代谢过程,可为未来深入理解碳氢...     

海洋环境中乙烷和丙烷的分布及生物转化

海洋沉积物中蕴含着大量以甲烷（CH₄）、乙烷（C₂H₆）和丙烷（C₃H₈）为主要成分的烷烃化合物,与甲烷类似,乙烷与丙烷也是重要的温室气体。水合物分解和油气渗漏会释放这些烷烃化合物到海水及大气中,对海洋生态环境及全球气候产生重要影响。海洋环境中的微生物对烷烃的氧化作用有效降低了海洋烷烃气体的排放通量。系统综述了海洋环境中乙烷和丙烷的分布及生物转化机制的最新研究进展,归纳出以下认识：（1）海水中乙烷与丙烷的分布特征明显,主要受到水文、化学及生物等环境参数的影响;（2）海洋环境中乙烷与丙烷的生物来源主要有海水中浮游植物生产释放和沉积物中厌氧微生物生成,产甲烷菌可以利用多种底物生成乙烷与丙烷;（3）乙烷和丙烷的好氧氧化主要由烷烃氧化菌完成,并且该过程中伴随一定程度的碳氢同位素分馏;（4）沉积物中乙烷与丙烷的厌氧氧化通常与硫酸盐还原耦合,目前已对参与氧化乙烷与丙烷的硫酸盐还原菌及厌氧氧化机制有了初步认识。总结和回顾了海洋环境中乙烷和丙烷的来源、分布及微生物代谢过程,可为未来深入理解碳氢...     

生物气研究现状与勘探前景

综合论述了生物气的特征及其研究进展,着重探讨了生物气成因、地球化学特征、勘探研究现状、生物气形成机制和控制因素,并介绍了生物气系统概念和特征,最后叙述了生物气藏的分布和我国生物气藏的远景。生物气是在还原环境的生物化学作用带内有机质为厌氧微生物所分解的最终产物,它以甲烷为主,并含部分二氧化碳及少量氮气和其它微量气体组分,生物甲烷气δ13C1值一般小于-55‰。生物甲烷气的形成途径主要有乙酸发酵和CO2还原2种类型。生物气生成与其所处的沉积环境、古气候、有机质的类型和丰度、水介质性质、地质作用、沉积时间等众多因素密切相关。生物气埋藏浅,分布广泛,一般存在于三角洲、大陆架和部分陆相沉积环境中,储层时代主要为白垩纪、古近纪、新近纪和第四纪。白垩纪的储量最丰富,古近纪、新近纪次之,第四纪生物气藏的规模一般较小。我国生物气勘探研究历史虽然不长,但生物气资源量丰富,具有良好的勘探前景。     

微生物白云岩形成机理、识别标志及存在的问题

关于白云岩成因,前人提出了多种机理,但许多机理并没有过硬的证据,难以令人信服.近些年的研究表明,白云石借助微生物的作用在常温下可以沉淀出来,形成微生物白云岩.模拟实验证明了这种机理的正确性.微生物白云岩的发现表明,自然界中可以存在原生白云岩,因此具有重要科学意义.实验表明,多种微生物可形成白云岩.文章主要描述了其中4类...     

Kinetics of biodegradation of diesel fuel by enriched microbial consortia from polluted soils

Three microbial consortia were isolated from three polluted soils located at an oil refinery and acclimated to grow on diesel fuel as the sole carbon source. Batch experiments were then conducted with the three consortia to study the kinetics of diesel biodegradation. The effects of temperature (25, 30 and 35?°C) and diesel concentration (0.5, 1 and 3?%) on the biodegradation of diesel were analysed. Several species were identified in the acclimated microbial consortia, and some of them appeared in more than one consortium. Thermal inhibition was observed at 35?°C. In the rest of experiments, over 80?% of the substrate was degraded after 40?h of treatment. These results proved the good feasibility of using the polluted sites as sources of mixed consortia for hydrocarbon degradation. However, diesel degradation efficiencies and rates were very similar, suggesting that the acclimation process produced mixed consortia with very similar characteristics; in this context, origin of the soil sample was not a decisive factor. A simple Monod-type kinetic model was used to simulate the biodegradation process, and accurate results were obtained. The ?? _max values were between 0.17 and 0.34?h^?1. The results of this study revealed that the consortia can function at high concentrations of hydrocarbons without any sign of growth inhibition, which is important for the design of bioreactors for wastewater treatment with high concentrations of fuel.     

Kinetic of biogenic sulfide production for microbial consortia isolated from soils with different bioaccessible concentrations of lead

Different technologies have been implemented for the treatment of acid mine drainage. Among these are technologies such as geochemical barriers and sulfidogenic reactors, which use biogenic sulfide (produced by sulfate-reducing bacteria) for metallic stabilization. Because both processes involve microorganisms, it is important to have a clear understanding of the factors that influence their activity in different toxic environments. Given that microbial communities isolated from polluted sites could have a higher tolerance to toxic ions, two consortia with sulfate-reducing activity were isolated from different soils impacted by mining activities. These soils had different total (401 and 19,300 mg Pb kg^?1), mobile (54 and 1,415 mg Pb kg^?1) and bioaccessible (316 and 3,175 mg Pb kg^?1) concentrations of lead. The kinetics of biogenic sulfide production (BSP) for both consortia were monitored in a batch reactor after they were exposed to different initial lead concentrations. These lead concentrations were established based on the results of lead mobility tests. The estimated BSP rates and biomass concentrations of both consortia showed different responses to the presence of lead. Results highlighted that lead sulfide precipitation on microbial cell is a tolerance mechanism identified and this one is triggered for the lead bioaccessible concentrations threshold in soil. These results could be useful for the designing of processes based on sulfate reducing activity for the removal or stabilization of metal present in water or soil, respectively.     

Selective digestion of industrial potato wastes for efficient biomethanation: a sustainable solution for safe environmental disposal

Potato being the staple vegetable in India is widely cultivated and processed for different value additions. During processing of potato, a huge amount of waste is generated in the form of peel and meat (mash). These wastes constitute a potential feedstock for biogas generation. The present study is focused on mitigation of acidogenesis that occurs during early stages of anaerobic digestion (AD) of potato waste which eventually inhibits the process of methanogenesis. A novel strategy of selective digestion was adopted in which the leachate and solid slurry resulting from the first stage digestion were further subjected to second stage by separating the solid and liquid phases. The obtained results indicated that stepwise digestion enhanced biomethane yield with an increase in methane percent from 46.47 to 60.4 % and reduction in total COD to about 94 %. Another novel strategy adopted in this study was the use of specifically developed microbial consortia for AD of potato wastes instead of conventional inoculum for production of biogas. The obtained yield is at par with the conventional inoculums which suggests that the developed consortia could act as potential substitute. The present study paves the way for sustainable utilization of industrial potato wastes for bioenergy production by overcoming the problems associated with conventional processes.     

Aerobic methanotrophy at ancient marine methane seeps: A synthesis

The molecular fingerprints of the chemosynthesis based microbial communities at methane seeps tend to be extremely well preserved in authigenic carbonates. The key process at seeps is the anaerobic oxidation of methane (AOM), which is performed by consortia of methanotrophic archaea and sulphate reducing bacteria. Besides the occurrence of ¹³C depleted isoprenoids and n-alkyl chains derived from methanotrophic archaea and sulphate reducing bacteria, respectively, ¹³C depleted triterpenoids have been reported from a number of seep deposits. In order to evaluate the significance of these apparently non-AOM related molecular fossils, the biomarker inventories of one Campanian and two Miocene methane seep limestones are compared. These examples provide strong evidence that methane was not solely oxidized by an anaerobic process. Structural and carbon isotope data reveal that aerobic methanotrophy was common at some ancient methane seeps as well. The Miocene Marmorito limestone contains abundant 3β-methylated hopanoids (δ¹³C: −100‰). Most likely, 3β-methylated hopanepolyols, prevailing in aerobic methanotrophs, were the precursor lipids of these compounds. A series of isotopically depleted 4-methylated steranes (lanostanes; δ¹³C: −80‰ to −70‰) and similarly isotopically depleted 17β(H),21β(H)-32-hopanoic acid in the Miocene Pietralunga seep limestone also are derived probably from aerobic methanotrophs. Lanosterol, which is known to be produced by aerobic methanotrophs, is the most likely precursor of 4-methylated steranes. Less obvious is the origin of 8,14-secohexahydrobenzohopanes (δ¹³C: −110‰ to −107‰) in Late Cretaceous seep limestones. These hopanoids probably reflect early degradational products of precursor lipids locally produced by seep endemic aerobic methanotrophs.     

Anaerobic digester sludge as nutrient source for culturing of microalgae for economic biodiesel production

After decades of ‘living dangerously’, the human kind has paused to think of Mother Nature. Alternate energy sources are being developed as a part of this realization. The use of indigenous sources of nutrients would considerably bring down the cost of production. A mixed consortium of Chlorella vulgaris, Arthrospira platensis, and tap water-originated Scenedesmus dimorphus was cultured using natural seawater, anaerobic digester sludge, and its growth was compared with synthetic commercial media like Zarrouk’s media, NaNO₃ media, and NH₄Cl media. A spectrophotometric method was standardized for regular biomass estimation. The dry biomass of a 15-day pure, batch culture of Arthrospira was found to yield around 600 mg/L in anaerobic digester sludge, whereas the pure batch culture of chlorella’s growth was hindered mainly due to the presence of bacteria and grazers. Regular microscopic observation and biomass monitoring revealed a drastic reduction in grazing activity, with the use of autoclaved AD sludge, resulting in a strong and stable microalgal mixed consortia. The consortia growth in AD sludge was found to be better than with the synthetic media with no cost of nutrient. The mixed consortia yielded a biomass up to 600 mg/L and lipid of 21.18%. The lipid generated from AD sludge had around 95% unsaturates and contained around 5% omega-3 fatty acids. The use of anaerobic digester sludge in a non-sterile condition reduces the total cost of the biodiesel production process as a whole and introduces a decentralized system for waste water treatment as well.     

Application of indigenous microbial consortia in bioremediation of oil-contaminated soils

Bioremediation of oil spillage in soils using consortia of microbes beckons much exploration. The present study involves bioremediation of oil-contaminated soils from north Chennai, India, using indigenous microbial consortia. Totally, 32 positive oil degrading isolates were obtained from 3 different locations, i.e., petrol filling stations, automobile workshops and oil refineries. Substrate utilization patterns of individual isolates and the consortial sets were observed. Mixture of three common hydrocarbons (petrol, diesel and engine oil) was used for studies. The substrate oil utilized by consortia was taken for thin-layer and column chromatography which perfectly resulted in varied fractions of oil compared to the unused oil as control. The best consortia were used directly for bioremediation experiment. Three different oil-contaminated soils were used and bioremediation patterns were observed. The rate of bioremediation differed within soils, nevertheless all soils were almost 100 % reclaimed within 30 days. Bioremediation kinetics showed that the process corresponds to first-order kinetics and kinetic constants for the different soils ranged from 0.051 to 0.077/day. Assessment of detoxification of acute phytotoxicity owing to the pollutant oil was done, and results observed were significant. An increase of 25, 300 and 212 % in germination index, average growth index and sustenance index, respectively, of Trigonella foenum-graecum Linn. in treated soils was observed, compared to untreated soils. Thus, this study confirmed that microbes in ‘Consortial Union’ serve as better treating agents in bioremediation of oil-contaminated soils than individual microorganisms.     

海洋沉积物中现存微生物化学标志物完整极性膜脂研究进展

完整极性膜脂作为活的微生物细胞的化学标志物,能够反映海洋沉积物中现存微生物群落结构和生物量等信息.与生物学方法相比,完整极性膜脂分析技术具有无需培养、快速和普适性等特点.综述了海洋沉积物中细菌和古菌的细胞膜完整极性膜脂的组成特点及其在生物地球化学和微生物生态学等研究中的应用,重点评述了在生物地球化学循环中有特殊作用的微生物,如厌氧氨氧化细菌、甲烷氧化古菌、氨氧化古菌、具有四醚膜脂结构的海洋泉古菌等,或者是一些特殊生态系统,如冷泉、海底深部生物圈等研究中完整极性膜脂应用的进展.还简要介绍了完整极性膜脂的分析方法,并对其应用前景进行了展望.     

Biogeochemical characterization of bacterial assemblages in relation to release of arsenic from South East Asia (Bangladesh) sediments

Arsenic release experiments using natural indigenous microbial assemblages and natural sediment samples in Bangladesh have been performed. The As release appears to be facilitated by moderate organic input. Addition of some nutrients caused reducing conditions, which may generate the appropriate environment for Fe-reducing bacteria to become active. Detailed cellular phospholipid fatty acid (PLFA) analysis suggests the presence of SO₄-reducing and Fe-reducing bacteria in the sediments. These Fe-reducing bacteria may serve as the agents catalyzing As release in the organic-rich sediments. 16S rDNA analysis of one cultured sample suggests the presence of clostridia, some of which are known to mediate Fe reduction. Based on new PLFA analyses, it is proposed that combined microbial processes of SO₄ reduction to generate anaerobic conditions and Fe reduction to co-reduce As are important biogeochemical factors for As release in the Bangladesh sediments.     

The effect of microbial glucose metabolism on bytownite feldspar dissolution rates between 5° and 35°C

The rate of Si release from dissolving bytownite feldspar in abiotic batch reactors increased as temperatures increased from 5° to 35°C. Metabolically inert subsurface bacteria (bacteria in solution with no organic substrate) had no apparent effect on dissolution rates over this temperature range. When glucose was added to the microbial cultures, the bacteria responded by producing gluconic acid, which catalyzed the dissolution reaction by both proton- and ligand-promoted mechanisms. The metabolic production, excretion, and consumption of gluconic acid in the course of glucose oxidation, and therefore, the degree of microbial enhancement of mineral dissolution, depend on temperature. There was little accumulation of gluconic acid and therefore, no significant enhancement of mineral dissolution rates at 35°C compared to the abiotic controls. At 20°C, gluconate accumulated in the experimental solutions only at the beginning of the experiment and led to a twofold increase in dissolved Si release compared to the controls, primarily by the ligand-promoted dissolution mechanism. There was significant accumulation of gluconic acid in the 5°C experiment, which is reflected in a significant reduction in pH, leading to 20-fold increase in Si release, primarily attributable to the proton-promoted dissolution mechanism. These results indicate that bacteria and microbial metabolism can affect mineral dissolution rates in organic-rich, nutrient-poor environments; the impact of microbial metabolism on aluminum silicate dissolution rates may be greater at lower rather than at higher temperatures due to the metabolic accumulation of dissolution-enhancing protons and ligands in solution.