Long- and short-chain AHLs affect AOA and AOB microbial community composition and ammonia oxidation rate in activated sludge

Quorum sensing (QS) regulation of the composition of ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) communities and functions in wastewater treatment was investigated. Specifically, we explored the role of N-acyl-l-homoserine lactones (AHLs) in microbial community dynamics in activated sludge. On average, the specific ammonia-oxidising-rate increased from 1.6 to 2.8?mg?NH₄⁺-N/g?MLSS/hr after treatment with long-chain AHLs for 16?days, and the addition of AHLs to sludge resulted in an increased number of AOA/AOB amoA genes. Significant differences were observed in the AOA communities of control and AHL-treated cultures, but not the AOB community. Furthermore, the dominant functional AOA strains of the Crenarchaeota altered their ecological niche in response to AHL addition. These results provide evidence that AHLs play an important role in mediating AOA/AOB microbial community parameters and demonstrate the potential for application of QS to the regulation of nitrogen compound metabolism in wastewater treatment.     

河蚬（Corbicula fluminea）扰动对表层沉积物中氨氧化菌群落结构和丰度的影响

为研究不同生物量河蚬(Corbicula fluminea)的生物扰动对表层沉积物中氨氧化菌群落结构和丰度的影响,本研究设计了沉积物-水微宇宙的模拟体系,通过构建克隆文库、实时荧光定量PCR(real-time qPCR)等分子生物学方法比较不同密度河蚬扰动的沉积物中氨氧化古菌(ammonia-oxidizing archaea,AOA)和氨氧化细菌(ammonia-oxidizing bacteria,AOB)群落结构和丰度差异.结果表明,河蚬的生物扰动作用对表层沉积物氮素释放有明显的促进作用.氨氧化菌(AOA和AOB)amoA基因克隆文库中,AOA的amoA基因序列包含了已知的海洋和土壤环境中的两个分支,AOB的amoA基因绝大部分序列都属于变形菌门β亚纲(β-Proteobacteria)中的亚硝化单细胞菌属(Nitrosomonas).3个处理组表层沉积物中细菌amoA基因丰度均高于古菌amoA基因丰度,且河蚬密度越高则细菌amoA的丰度越低.同时,河蚬的添加使得微宇宙体系中氨氧化菌(AOA和AOB)的多样性降低.综上,河蚬的生物扰动对表层沉积物中氨氧化菌群落结构和丰度产生了一定的影响.     

填埋场古细菌垂直分布格局及其与垃圾降解程度响应特征

研究了青岛市小涧西垃圾填埋场表层(3 ～ 12 m)、中上层(15～24 m)、中下层(27 ～36 m)和底层(39 ～45 m)古细菌的多样性、群落组成与垂直分布特征,以及垃圾降解程度与古细菌群落结构演替变化的响应关系.结果表明:垃圾有机质和凯氏氮含量随填埋深度增加呈降低趋势,而pH呈微弱升高趋势.填埋场中下层的古...     

利用垃圾渗滤液富集培养氨氧化菌

确保活性污泥中适当的氨氧化菌(AOB)的数量及活性对污水生物除氮过程至关重要,投加富集AOB是增加活性污泥中AOB浓度的方法之一. 为了经济有效地获取富集的AOB并有效处理难降解的垃圾渗滤液,对利用垃圾渗滤液富集培养AOB的可行性进行了研究. 采用烟台市生活垃圾填埋场的垃圾渗滤液作为培养基,利用辛安河污水处理厂A2/O工艺二沉池的回流污泥进行接种,通过更代方式富集培养AOB. 结果显示:更代4次后,菌液中AOB的浓度增至原来的5.6倍;向活性污泥中投加14.5%的经过4次更代富集培养的AOB,氨氧化速率提高了65.4%,从而验证了利用垃圾渗滤液富集AOB是可行的.      

超声波-缺氧／好氧污泥消化反应器中氨氧化细菌群落结构的演变

为了揭示超声波-缺氧／好氧污泥消化反应器中氨氧化细菌群落结构多样性的演变过程,采用变性梯度凝胶技术（PCR—DGGE）研究不同运行时期氨氧化细菌群落结构的变化。DGGE分析表明,反应器中氨氧化细菌群落比较丰富。在反应器运行的不同时期,氨氧化细菌的群落结构发生了一定的变化,反映了种群的动态演变。UPGMA聚类分析将DGGE图谱分为3大类群并对应于各自的运行时期。测序结果表明,反应器中的优势种群属于变形菌门（Proteobacteria）,包括α-proteobacteria,β-proteobacteria,γ-proteobacteria和ε-proteobacteria4个纲,其中β-proteobacteria占45％,γ-proteobacteria占40％。在始终保持明显优势地位的种属中,5株为反硝化细菌,它们对提高反应器脱氮效率具有重要作用。     

草海湖滨带沉积物微生物群落对磷形态的影响

为探究高原湖泊湖滨带沉积物中微生物群落对磷赋存形态的影响,以草海湖滨带沉积物为研究对象,分析了磷素赋存形态;通过高通量测序技术分析了细菌和古菌的群落组成.结果表明,草海湖滨带表层沉积物的总磷含量范围在662.89~881.26mg/kg之间,平均值为750.36mg/kg;各磷形态中NaOH-NRP＞Res-P＞BD-P＞HCl-P＞NaOH-SRP＞NH₄Cl-P.细菌群落由变形菌门(Proteobacteria)等59个门和硫杆菌属(Thiobacillus)、厌氧粘细菌属(Anaeromyxobacter)等1259个属组成;古菌群落由泉古菌门(Crenarchaeota)等8个门和甲烷丝菌属(Methanosaeta)等67个属组成.冗余分析、主成分分析和共现性网络分析表明,微生物群落能驱动草海沉积物中磷的形态转化,细菌主要通过影响铁的氧化/还原和碱性磷酸酶的活性;古菌则通过改变有机质和酸性磷酸酶活性来调控沉积物磷形态.     

An innovative membrane bioreactor and packed-bed biofilm reactor combined system for shortcut nitrification-denitrification

An innovative shortcut biological nitrogen removal system, consisting of an aerobic submerged membrane bioreactor (MBR) and an anaerobic packed-bed biofilm reactor (PBBR), was evaluated for treating high strength ammonium-bearing wastewater. The system was seeded with enriched ammonia-oxidizing bacteria (AOB) and operated without sludge purge with a decreased hydraulic retention time (HRT) through three phases. The MBR was successful in both maintaining nitrite ratio over 0.95 and nitrification efficiency higher than 98% at a HRT of 24 h. The PBBR showed satisfactory denitrification efficiency with very low effluent nitrite and nitrate concentration (both below 3 mg/L). By examining the nitrification activity of microorganism, it was found that the specific ammonium oxidization rate (SAOR) increased from 0.17 to 0.51 g N/(g VSS·d) and then decreased to 0.22 g N/(g VSS·d) at the last phase, which resulted from the accumulation of extracellular polymers substances (EPS) and inert matters enwrapped around the zoogloea. In contrast, the average specific nitrite oxidization rate (SNOR) is 0.002 g N/(g VSS·d), only 1% of SAOR. Because very little Nitrobactor has been detected by fluorescence in situ hybridization (FISH), it is confirmed that the stability of high nitrite accumulation in MBR is caused by a large amount of AOB.     

双氰胺和3,4-二甲基吡唑磷酸盐对蔬菜种植土壤氨氧化细菌和古菌的影响

硝化抑制剂双氰胺(DCD)和3,4-二甲基吡唑磷酸盐(DMPP)在抑制农业土壤硝化作用和提高氮肥利用率等方面效果显著,为了探讨它们对蔬菜种植土壤氨氧化细菌(AOB)和古菌(AOA)的作用机制,选取40 a以上蔬菜种植土壤,在施加尿素(CK)基础上,分别添加DCD和DMPP进行室内培养,系统监测了土壤中NH_4~+-N、NO_3~--N和硝化势的变化,同时运用荧光定量PCR和高通量测序等技术揭示了AOB和AOA种群丰度和多样性的演替规律.结果表明,相比CK处理,DCD处理和DMPP处理的NH_4~+-N含量升高了213%和675%; NO_3~--N含量降低了13. 3%和37. 2%;硝化势降低了20. 4%和82. 4%;同时,AOB丰度降低了51. 2%和56. 5%; AOA丰度降低了6. 0%和27. 0%.不同抑制剂处理间AOB和AOA的α多样性指数没有显著差异; nork-environmental-samples、unclassified-Nitrosomonadaceae、unclassified-Bactertia和Nitrosospira是AOB序列属水平的主要优势类群; norank-Crenarchaeota、norank-enviromental-samples和Nitrososphaera是AOA序列属水平的主要优势类群,施用DCD和DMPP显著改变了AOB和AOA的群落组成.综上所述,尿素与DCD和DMPP配施显著抑制NH_4~+-N的转化,降低AOB和AOA的种群丰度并改变其群落组成.相比DCD,DMPP对硝化作用的抑制和对AOB和AOA群落的影响更强.     

Abundance and diversity of ammonia-oxidizing archaea in response to various habitats in Pearl River Delta of China, a subtropical maritime zone

Ammonia-oxidizing archaea (AOA) are widely considered key to ammonia oxidation in various environments. However, little work has been conducted to simultaneously investigate the abundance and diversity of AOA as well as correlations between archaeal amoA genotypes and environmental parameters of different ecosystems at one district. To understand the abundance, diversity, and distribution of AOA in Pearl River Delta of China in response to various habitats, the archaeal amoA genes in soil, marine, river, lake, hot spring and wastewater treatment plant (WWTP) samples were investigated using real-time fluorescent quantitative PCR and clone libraries. Our analyses indicated that the diversity of AOA in various habitats was different and could be clustered into five major clades, i.e., estuary sediment, marine water/sediment, soil, hot spring and Cluster 1. Phylogenetic analyses revealed that the structure of AOA communities in similar ecological habitats exhibited strong relation. The canonical correspondence method indicated that the AOA community structure was strongly correlated to temperature, pH, total organic carbon, total nitrogen and dissolved oxygen variables. Assessing AOA amoA gene copy numbers, ranging from 6.84×10⁶ to 9.45×10⁷ copies/g in dry soil/sediment, and 6.06×10⁶ to 2.41×10⁷ copies/L in water samples, were higher than ammonia-oxidizing bacteria (AOB) by 1-2 orders of magnitude. However, AOA amoA copy numbers were much lower than AOB in WWTP activated sludge samples. Overall, these studies suggested that AOA may be a major contributor to ammonia oxidation in natural habitats but play a minor role in highly aerated activated sludge. The result also showed the ratio of AOA to AOB amoA gene abundance was positively correlated with temperature and less correlated with other environmental parameters. New data from our study provide increasing evidence for the relative abundance and diversity of ammonia-oxidizing archaea in the global nitrogen cycle.     

北运河闸坝区水体氨氧化微生物及硝化活性特征研究

采用分子荧光定量PCR对北运河闸坝区(上游沙河闸和下游杨洼闸)水体中氨氧化细菌(AOB)的amoA基因拷贝数进行定量测定,并研究了闸坝设置和排污口污水排放对AOB的amoA基因拷贝数,硝化活性(NA)和氮素转化的影响.结果表明,1在沙河闸段,AOB的amoA基因拷贝数呈现先上升后下降,排污口处又显著上升的空间变化特征,其变化范围为(1.84±0.09)×10~8~(7.12±0.36)×10~8copies·L~(-1),排污口处最高;在杨洼闸段,amoA基因拷贝数呈现先上升后下降最后趋于平稳的空间变化特征,其变化范围为(3.05±0.15)×10~8~(6.83±0.34)×10~8copies·L~(-1),下游100 m处最高.闸坝的设置和排污口污水的排放对AOB的amoA基因拷贝数和空间分布具有显著影响.2硝化活性(NA)的空间变化特征与AOB的变化特征相同.闸坝的设置和污水排放能促进水体的硝化过程,加快污染物质的降解.3沙河闸排污口处排放的NH_4~+-N可以作为AOB生长的氮源,提高硝化活性,加快NH_4~+-N全向NO_3~--N的转化,促进硝化过程的完全进行;杨洼闸段闸门的开启导致溶解氧的升高和内源NO_3~--N的释放,为AOB的生长提供氮源,提高硝化活性,但造成了NO_2~--N的积累.