巢湖完全氨氧化细菌的丰度、群落结构及其影响因素研究

完全氨氧化过程（complete ammonia oxidation, comammox）的发现使研究者们对硝化作用和氮循环都有了新的认识.本研究选取巢湖冬夏季表层（0~10 cm）沉积物样品,运用高通量测序、实时定量PCR等分子生物学技术对comammox细菌的丰度和群落结构进行研究.结果表明：基于amoA基因的comammox细菌的丰度为（5.20±0.72）×10⁶~（4.06±1.23）×10⁷ copies·g^-1;氨氧化古菌的丰度为（5.39±1.01）×10⁵~（1.60±0.18）×10⁷ copies·g^-1;氨氧化细菌的丰度为（6.16±1.57）×10⁵~（4.30±0.19）×10⁶ copies·g^-1.comammox细菌的绝对丰度显著高于氨氧化古菌和氨氧化细菌.多样性分析表明冬季巢湖表层沉积物中的comammox细菌的物种多样性大于夏季.其中Candidatus Nitrospira nitrificans、Candidatus Nitrospira nitrosa和Candidatus Nitrospira inopinata的相对丰度最高占比分别为78.72%、49.80%和6.28%,且夏季样点中Candidatus Nitrospira inopinata的相对丰度显著高于冬季样点.主坐标分析（Principle Coordinate Analysis, PcoA）结果表明,comammox细菌的群落结构具有明显的时间异质性.理化因子中,NH₄⁺和NO₃^-与comammox细菌的丰度呈负相关关系.本研究在一定程度上揭示了comammox细菌的丰度、群落组成、多样性及其与理化因子的关系.     

嗜热自养甲烷杆菌的抗逆分子机制

为揭示嗜热厌氧古菌适应极端环境的分子机理,分别在不同温度(50℃,60℃,65℃和70℃)培养嗜热自养甲烷杆菌,利用Real-time RT-PCR研究其二硫键异构酶(mtPDI)mRNA的表达情况.结果显示,mtPDI mRNA在上述情况下都有表达,但当温度偏离菌体最适生长温度(65℃),表达量会提高,在50℃和70...     

Functional relationship between ammonia-oxidizing bacteria and ammonia-oxidizing archaea populations in the secondary treatment system of a full-scale municipal wastewater treatment plant

The abundance of ammonia-oxidizing bacteria and archaea and their amoA genes from the aerobic activated sludge tanks, recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant (WWTP) was determined. Polymerase chain reaction and denaturing gradient gel electrophoresis were used to generate diversity profiles, which showed that each population had a consistent profile although the abundance of individual members varied. In the aerobic tanks, the ammonia-oxidizing bacterial (AOB) population was more than 350 times more abundant than the ammonia-oxidizing archaeal (AOA) population, however in the digesters, the AOA population was more than 10 times more abundant. Measuring the activity of the amoA gene expression of the two populations using RT-PCR also showed that the AOA amoA gene was more active in the digesters than in the activated sludge tanks. Using batch reactors and ddPCR, amoA activity could be measured and it was found that when the AOB amoA activity was inhibited in the anoxic reactors, the expression of the AOA amoA gene increased fourfold. This suggests that these two populations may have a cooperative relationship for the oxidation of ammonia.     

高钙废水颗粒污泥中古菌菌群结构变化的分析

为了解高浓度Ca~(2+)与颗粒污泥中古菌菌群结构的关系,利用高通量测序分析IC(Internal Circulation)反应器(以废纸造纸废水为处理对象)内不同高度处颗粒污泥中古菌菌群组成,并利用SEM(Scanning Electron Microscope)和EDS(Energy Dispersive X-ray Spectroscopy)分析颗粒污泥的形态结构和元素组成,同时借助红外光谱和XRD(X-ray diffraction)分析不同高度处颗粒污泥化学结构中各官能团的分布情况和无机成分.结果表明,随着反应器高度的增加,颗粒污泥中的无机成分CaCO_3也随着增加,而种泥中钙含量只有1.81%.种泥和ICR反应器内的颗粒污泥中古菌在门分类水平上主要包括Euryarchaeota和Bathyarchaeota,两者之和占90%以上.在属分类水平上,主要包括Methanosaeta、Methanoregula、Methanobacterium、Methanosarcina、Methanolinea、Methanospirillum等.种泥中古菌的物种多样性要明显高于IC反应器中,在IC反应器中不同高度处古菌生物多样性由高到低的顺序是5 m2 m7 m,5 m处的古菌物种更加丰富.随着反应器高度的增加,乙酸营养型甲烷菌的相对丰度呈现递增趋势,氢营养型甲烷菌则呈现递减趋势,而种泥中氢营养型甲烷菌相对丰度较大.这表明颗粒污泥在高钙废水的长期作用下,氢营养型甲烷菌的相对丰度减少,乙酸营养型甲烷菌的相对丰度增多,系统中古菌物种的相对丰度和多样性有所下降.CaCO_3沉淀使颗粒污泥的产甲烷活性降低,主要表现为其对氢营养型甲烷菌具有较大的抑制作用.     

Editorial: Effects of metal contamination on ammonia-oxidizing microorganisms in a freshwater reservoir

<正>Ammonia-oxidizing microorganisms, including ammoniaoxidizing bacteria (AOB) and archaea (AOA), are important to the global nitrogen cycle. These microbes catalyze the oxidization of ammonia (NH_3) to nitrite (NO_2~-), the ratelimiting step in the biogeochemical cycling of nitrogen (Stahl and de la Torre, 2012). Effects on the activity of the ammoniaoxidizing microbes could ultimately influence the global     

Response of ammonia-oxidizing archaea to heavy metal contamination in freshwater sediment

It has been well-documented that the distribution of ammonia-oxidizing bacteria(AOB) and archaea(AOA) in soils can be affected by heavy metal contamination, whereas information about the impact of heavy metal on these ammonia-oxidizing microorganisms in freshwater sediment is still lacking. The present study explored the change of sediment ammonia-oxidizing microorganisms in a freshwater reservoir after being accidentally contaminated by industrial discharge containing high levels of metals. Bacterial amoA gene was found to be below the quantitative PCR detection and was not successfully amplified by conventional PCR. The number of archaeal amoA gene in reservoir sediments were 9.62 × 10~2–1.35 × 10~7 copies per gram dry sediment. AOA abundance continuously decreased, and AOA richness, diversity and community structure also considerably varied with time. Therefore, heavy metal pollution could have a profound impact on freshwater sediment AOA community. This work could expand our knowledge of the effect of heavy metal contamination on nitrification in natural ecosystems.     

Overlooked nitrogen-cycling microorganisms in biological wastewater treatment

• AOA and comammox bacteria can be more abundant and active than AOB/NOB at WWTPs. • Coupled DNRA/anammox and NO_x-DAMO/anammox/comammox processes are demonstrated. • Substrate level, SRT and stressors determine the niches of overlooked microbes. • Applications of overlooked microbes in enhancing nitrogen removal are promising. Nitrogen-cycling microorganisms play key roles at the intersection of microbiology and wastewater engineering. In addition to the well-studied ammonia oxidizing bacteria, nitrite oxidizing bacteria, heterotrophic denitrifiers, and anammox bacteria, there are some other N-cycling microorganisms that are less abundant but functionally important in wastewater nitrogen removal. These microbes include, but not limited to ammonia oxidizing archaea (AOA), complete ammonia oxidation (comammox) bacteria, dissimilatory nitrate reduction to ammonia (DNRA) bacteria, and nitrate/nitrite-dependent anaerobic methane oxidizing (NO_x-DAMO) microorganisms. In the past decade, the development of high-throughput molecular technologies has enabled the detection, quantification, and characterization of these minor populations. The aim of this review is therefore to synthesize the current knowledge on the distribution, ecological niche, and kinetic properties of these “overlooked” N-cycling microbes at wastewater treatment plants. Their potential applications in novel wastewater nitrogen removal processes are also discussed. A comprehensive understanding of these overlooked N-cycling microbes from microbiology, ecology, and engineering perspectives will facilitate the design and operation of more efficient and sustainable biological nitrogen removal processes.     

Community diversity and distribution of ammonia-oxidizing archaea in marsh wetlands in the black soil zone in North-east China

AOA amoA genes in the soils of the two wetlands affiliated with three lineages. The main drivers of AOA community were pH and total organic carbon and ammonium. The soil characteristics rather than the vegetation control the AOA community. Since its first detection, ammonia-oxidizing archaea (AOA) have been proven to be ubiquitous in aquatic and terrestrial ecosystems. In this study, two freshwater marsh wetlands- the Honghe wetland and Qixinghe wetland – in the black soil zone in North-east China were chosen to investigate the AOA community diversity and distribution in wetland soils with different vegetation and depth. In the Honghe wetland, two sampling locations were chosen as the dominant plant transited from Deyeuxia to Carex. In the Qixinghe wetland, one sample location that was dominated by Deyeuxia was chosen. Samples of each location were collected from three different depths, and Illumina MiSeq platform was used to generate the AOA amoA gene archive. The results showed that the AOA amoA genes in the soils of the two wetlands were affiliated with three lineages: Nitrososphaera, Nitrosotalea, and Nitrosopumilus clusters. The different dominant status of these AOA lineages indicated their differences in adapting to acidic habitat, oxygenic/hypoxic alternation, organic matter, and other environmental factors, suggesting high diversity among AOA in marsh soils. The main driver of the AOA community was pH, along with organic carbon and ammonium nitrogen, which also played an important role combined with many other environmental factors. Thus, soil physiochemical characteristics, rather than vegetation, were the main cause of AOA community diversity in the wetlands in the black soil zone in China.     

黄河三角洲土壤古菌群落结构对盐生植被演替的响应

采用高通量测序技术,探究黄河三角洲光板地和4种典型盐生植被类型（翅碱蓬、獐茅、白茅和罗布麻）下土壤古菌群落组成和数量分布特征,揭示其对盐生植被演替的响应.结果表明,植被覆盖有利于降低土壤盐化程度、增加土壤营养物质含量,土壤速效磷随盐生植被在光板地-重盐土壤（翅碱蓬、獐茅）-轻盐土壤（白茅、罗布麻）中的正向演替有不断升高的趋势.5种覆被类型下土壤古菌在种群组成上差异明显,无植被覆盖的光板地具有最高的古菌群落多样性和丰富度,广古菌门为优势菌群.土壤古菌群落结构与盐生植被演替顺序不具有严格的一致性：当植被处于相同演替阶段时,土壤古菌群落结构不具明显的相似性;在不同演替阶段时,土壤古菌群落结构也未均表现出更大的差异性.随着盐生植被正向演替,土壤温度、电导率（含盐量）对土壤古菌群落结构多样性起促进作用,土壤全氮、碱解氮、有机质起抑制作用.     

铜胁迫对农田土壤酶活性、细菌和古菌数量的影响

为了研究铜矿周边农田土壤中不同Cu含量对土壤酶活性、细菌和古菌基因拷贝数的影响,在铜矿周边农田土壤中采集了8个不同Cu含量的土壤,测定土壤的酶活性、细菌和古菌基因拷贝数,结果表明,土壤总Cu含量为28.30~1 019.27mg·kg~(-1),酸可提取态Cu含量为335~415.11 mg·kg~(-1),细菌16S rRNA基因拷贝数在每克干土3.10×10~(10)~1.84×10~(11)个之间,古茵16S rRNA基因拷贝数在每克干土737×10~8~6.82×10~9个之间。土壤总Cu和酸可提取态Cu含量对土壤脲酶活性影响较大,但对土壤脱氢酶和转化酶活性影响不显著。土壤细菌基因拷贝数均与总Cu含量、各形态Cu含量呈极显著的负相关关系,同样土壤古菌基因拷贝数与总Cu含量、各形态Cu含量也均呈极显著的负相关关系,说明Cu胁迫对土壤细菌和古菌活性具有较大的抑制作用。