Temporal characteristics of algae-denitrifying bacteria co-occurrence patterns and denitrifier assembly in epiphytic biofilms on submerged macrophytes in Caohai Lake,SW China

Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats.However,little is known about the connection between algae and denitrifying bacteria and their assembly processes in epiphytic biofilms.Epiphytic biofilms were collected from submerged macrophytes(Patamogeton lucens and Najas marina L.)in the Caohai Lake,Guizhou,SW China,from July to November 2020 to:(1)investigate the impact of abiotic and biotic variables on denitrifying bacterial communities;(2)investigate the temporal variation of the algae-denitrifying bacteria co-occurrence networks;and(3)determine the contribution of deterministic and stochastic processes to the formation of denitrifying bacterial communities.Abiotic and biotic factors influenced the variation in the denitrifying bacterial community,as shown in the Mantel test.The co-occurrence network analysis unveiled intricate interactions among algae to denitrifying bacteria.Denitrifying bacterial community co-occurrence network complexity(larger average degrees representing stronger network complexity)increased continuously from July to September and decreased in October before increasing in November.The co-occurrence network complexity of the algae and nirS-encoding denitrifying bacteria tended to increase from July to November.The co-occurrence network complexity of the algal and denitrifying bacterial communities was modified by ammonia nitrogen(NH_(4)^(+)-N)and total phosphorus(TP),pH,and water temperature(WT),according to the ordinary least-squares(OLS)model.The modified stochasticity ratio(MST)results reveal that deterministic selection dominated the assembly of denitrifying bacterial communities.The influence of environmental variables to denitrifying bacterial communities,as well as characteristics of algal-bacterial co-occurrence networks and the assembly process of denitrifying bacterial communities,were discovered in epiphytic biofilms in this study.The findings could aid in the appropriate understanding and use of epiphytic biofilms denitrification function,as well as the enhancement of water quality.

Isolation of Denitrifying Bacteria in Sea Sediment and Simulated Experiment of Removing Nitrate-N from Seawater

The objective of this research was to isolate denitrifying bacteria from sea sediment and simulate the removal efficiency of nitrate-N by denitrifying bacteria from seawater. The result showed that the isolated denitrifying bacteria could effectively remove nitrate-N from seawater. About 90 % of nitrate-N was removed by denitrifying bacteria from seawater within a week in the simulated experiment I （the initial concentration of nitrate-N was 100 mg/L）. The removal efficiency of nitrate-N reached about 70 % within one day in the simulated experiment Ⅱ （initial concentration of nitrate-N was 1 mg/L）. The final removal efficiency was about 98 % and 85 % in the simulated experiments Ⅰ and Ⅱ, respectively. It was found that there was positive correlation between the concentration of nitrate-N and the number of denitrifying bacteria in seawater. Lots of denitrifying bacteria would disappear and the seawater would become transparent once the process of bioremediation was completed.

Impact of Long-Term Fertilization on Community Structure of Ammonia Oxidizing and Denitrifying Bacteria Based on amoA and nirK Genes in a Rice Paddy from Tai Lake Region,China

Ammonia oxidizing （AOB） and denitrifying bacteria （DNB） play an important role in soil nitrogen transformation in natural and agricultural ecosystems. Effects of long-term fertilization on abundance and community composition of AOB and DNB were studied with targeting ammonia monooxygenase （amoA） and nitrite reductase （nirK） genes using polymerase chain reaction- denaturing gradient gel electrophoresis （PCR-DGGE） and real-time PCR, respectively. A field trial with different fertilization treatments in a rice paddy from Tai Lake region, centre East China was used in this study, including no fertilizer application （NF）, balanced chemical fertilizers （CF）, combined organic/inorganic fertilizer of balanced chemical fertilizers plus pig manure （CFM）, and plus rice straw return （CFS）. The abundances and riehnesses of amoA and nirK were increased in CF, CFM and CFS compared to NF. Principle component analysis of DGGE profiles showed significant difference in nirK and amoA genes composition between organic amended （CFS and CFM） and the non-organic amended （CF and NF） plots. Number of amoA copies was significantly positively correlated with normalized soil nutrient richness （NSNR） of soil organic carbon （SOC） and total nitrogen （T-N）, and that of nirK copies was with NSNR of SOC, T-N plus total phosphorus. Moreover, nitrification potential showed a positive correlation with SOC content, while a significantly lower denitrification potential was found under CFM compared to under CFS. Therefore, SOC accumulation accompanied with soil nutrient richness under long-term balanced and organic/inorganic combined fertilization promoted abundance and diversity of AOB and DNB in the rice paddy.

Operation of three parallel AN/AO processes to enrich denitrifying phosphorus removing bacteria for low strength wastewater treatment

Three parallel anaerobic-anoxic/anaerobic-aerobic （AN/AO） processes were developed to enrich denitrifying phosphorus removal bacteria （DPB） for low strength wastewater treatment. The main body of the parallel AN/AO process consists of an AN （anaerobic-anoxic） process and an AO （anaerobic-aerobic） process. In the AO process, the common phosphorus accumulating organisms （PAOs） was dominate, while in the AN process, DPB was dominate, The volume of anaerobic zone（Vana）：anoxie zone（Vano） ： aerobic zone （Vaer） for the parallel AN/AO process is 1：1：1 in contrast with a Vana：Vaer and Vano：Vaer of 1：2 and 1：4 for a traditional biological nutrient removal process （BNR）. Process 3 excels in the 3 processes on the basis of COD, TN and TP removal. For 4 month operation, the effluent COD concentration of process 3 did not exceed 60 mg/L; the effluent TN concentration of process 3 was lower than 15 mg/L; and the effluent TP concentration of process 3 was lower than 1 mg/L.

Identification and Metabolic Mechanism of Non-fermentative Short-cut Denitrifying Phosphorus-removing Bacteria

To investigate the characteristics and metabolic mechanism of short-cut denitrifying phospho- rus-removing bacteria （SDPB） that are capable of enhanced biological phosphorus removal （EBPR） using nitrite as an electron acceptor, an aerobic/anoxic sequencing batch reactor was operated under three phases. An SDPB-strain YC was screened after the sludge enrichment and was identified by morphological, physiological, biochemical properties and 16S rDNA gene sequence analysis. Denitrifying phosphorus-removing experiments were conducted to study anaerobic and anoxic metabolic mechanisms by analyzing the changes of chemical oxygen demand （COD）, phosphate, nitrite, poly-fl-hydroxybutyrate （PHB）, and glycogen. The results show that strain YC is a non-fermentative SDPB similar to Paracoccus denitrificans. As a kind of non-fermentative bacteria, the energy of strain YC was mainly generated from phosphorus release （96.2%） under anaerobic conditions with 0.32 mg P per mg synthesized PHB. Under anoxic conditions, strain YC accumulated 0.45 mg P per mg degraded PHB, which produced most of energy for phosphate accumulation （91.3%） and a little for glycogen synthesis （8.7%）. This metabolic mechanism of strain YC is different from that of traditional phosphorus-accumulating organisms （PAOs）. It is also found that PHB, a kind of intracellular polymer, plays a very important role in denitrifying and accumulating phosphorus by supplying sufficient energy for phosphorous accumulation and carbon sources for denitrification. Therefore, monitoring AP/APHB and ANO2 -N/APHB is more necessary than monitoring AP/ACOD, ANO2 -N/ACOD, or AP / ANO2 -N.

Denitrifying Bacteria in Paddy Soils of the Taihu Lake Basin,China

This study attempted to determine the characteristics of the communities, the ecological factors, and the denitrifying enzyme activity for denitrifying bacteria found in the paddy soils of the Taihu Lake Basin, China. Samples of the six main soil types of the basin were taken from paddy fields with different fertilities. The total numbers of bacteria and denitrifying bacteria in the high fertility soils were much more than those in low fertility soils, and the number of denitrifying bacteria accounted for 49% to 80% of the total number of bacteria. The O2 content was an important ecological factor that affected denitrification. Of test the strains isolated from the paddy soils in the Taihu Lake Basin, some (e.g., Pseudomonas spp.) grew well under low oxygen partial pressure, while others (e.g., Bacillus spp.) had no strict predilection with O2 content. Another critical ecological factor was the nitrogen concentration. Three selected denitrifying bacteria grew better in aculture medium with 135 instead of 276mg L^-1 nitrogen. At the same time 67% of the test strains were able to reduce NO3^- to NO2^- and 56% had N2O reductase.

Community structure and assembly of denitrifying bacteria in epiphytic biofilms in a freshwater lake ecosystem

Denitrifying bacteria are a crucial component of aquatic ecosystem in nitrogen cycle.However,the denitrifying bacterial community dynamics and structure in epiphytic biofilms remain unexplored.The abundance of denitrification gene(nir)and structure of nirS-denitrifying bacterial community in the epiphytic biofilms collected in July and November of 2018 from a typical plateau lake(Caohai Wetland,Guizhou,China)were studied by Real-time Quantitative Polymerase Chain Reaction(qPCR)and highthroughput sequencing.Results show that the gene abundance of nirK was higher than that of nirS(P<0.05),and it was significantly different during the growth period(July)than the decline period(November).The denitrifying bacterial species was similar in the two months and shared 76.18%of OTUs.Proteobacteria(56.55%±22.15%)was the dominant phylum in all the samples.Epiphytic biofilms between growth period and decline period displayed significantly different microbial community structures due to differences in species abundance.Water temperature was the crucial factor that affected the denitrifying microbial community structure in our study.Environmental factors explain only partially the dynamic characteristics of denitrifying microbial communities,implying that the stochastic processes affected the construction of denitrifying microbial communities.As the null model analysis results show,dispersal limitation(stochastic)and undominated processes significantly influenced the assembly of denitrifying microbial communities.This study broadened our understanding of the denitrifying bacterial community structure and its function on epiphytic biofilms in freshwater ecosystems with new information provided.

Effect of Zinc Oxide Nanoparticles on Denitrification and Denitrifying Bacteria Communities in Typical Estuarine Sediments

For revealing the effects of increasing of zinc oxide nanoparticles(ZnO NPs)on denitrification and denitrifying bacteria communities in estuarine sediments,the surface sediments of two typical estuaries(the Yangtze River Estuary and the Yellow River Estuary)were added with medium concentration(170mgL−1)and high concentration(1700mgL−1)of ZnO NPs for anaerobic cul-ture in laboratory.The concentration of NO_(3)^(−)and NO_(2)^(−),the reductase activity and denitrification rate were measured by physico-chemical analysis,nirS gene abundance and denitrifying bacteria communities by molecular biological methods.The results showed that ZnO NPs inhibited NO_(3)^(−), NO_(2)^(−)reduction process and NO_(3)^(−), NO_(2)^(−)reductase activity,and a stronger inhibition effect resulting from the higher ZnO NPs concentration.ZnO NPs decreased nirS gene abundance and community diversity of denitrifying bacteria.In addition,the inhibition degree of ZnO NPs on the denitrification process of sediments in different estuaries was different.These results were of great significance for evaluating the potential ecological toxicity and risks of nanomaterials in estuaries.

减氮对麦玉轮作农田土壤反硝化细菌群落结构和多样性的影响

探究减氮对华北地区麦玉轮作农田土壤反硝化细菌群落结构和多样性影响,为华北地区麦玉轮作农田氮肥管理提供技术支持,本研究以不施氮为对照(CK),设置2个施氮量,分别为常规施氮量(纯氮300 kg·hm^(-2),N2)、减氮20%(纯氮240 kg·hm^(-2),N1),提取土壤DNA,用nirS(细胞色素cd1-亚硝酸还原酶)、nirK(Cu-亚硝酸还原酶)引物扩增后采用MiSeq PE300测序技术,研究施氮量对麦玉轮作农田土壤性状及nirS、nirK反硝化细菌群落结构及多样性的影响。结果表明,3个处理nirS、nirK反硝化细菌α-多样性指数无显著差异,nirS反硝化细菌α-多样性高于nirK。减氮显著影响nirS、nirK反硝化细菌物种组成。减氮对nirS、nirK反硝化细菌门水平及nirK纲水平物种组成无显著影响,但显著降低了nirS反硝化细菌Deltaproteobacteria(δ-变形菌纲)相对丰度;减氮显著影响nirS、nirK属水平物种组成。硝态氮、速效磷、pH值是影响土壤nirS反硝化细菌属水平群落结构主要环境因子;pH值是影响土壤nirK反硝化细菌属水平群落结构的主要环境因子。研究表明,适量减氮不影响反硝化细菌α-多样性,但显著影响反硝化细菌属水平群落组成和群落结构,减氮主要是通过影响土壤性状及微生物群落结构进而影响农田土壤N2O排放。

污水厂尾水对河流水质和底泥细菌群落的影响

污水厂的出水即尾水,其排放关系到受纳水体的水质和生态状况。分析了武汉市某污水厂尾水排放指标,采用水槽试验探究了污水厂尾水对河流水质指标和底泥细菌群落的影响。结果表明:尾水排放促进了河水中硝酸盐氮的降解,总磷去除更加稳定;尾水使河水pH值提高了0.3、电导率上升幅度55%、溶解氧降低了0.6 mg/L。尾水排放之后,底泥细菌群落的丰富度升高、多样性降低,抑制厌氧菌Anaerolineaceae和SBR1031,促进好氧菌Pseudomonas;反硝化菌Azospira、Dechloromonas、Pseudomonas、Sphingomonas增多,促进了NO_(3)^(-)-N的降解。底泥中致病菌奈瑟菌属、军团菌属、消毒残生细菌相对丰度上升。

接种两株有益菌的生物絮团净水性能及饲料化潜力

为强化新的絮团形成菌伪杜擀氏菌YN12(Pseudoduganella eburnea YN12,YN)利用养殖尾水生成生物絮团效果,并将絮团制成饲料,探讨在胡子鲶(Claris fuscus)饲养上的可行性。在生物絮团系统中,接种活性污泥(Activated sludge,AS)、伪杜擀氏菌YN12和枯草芽孢杆菌(Bacillus subtilis,BS)并配制成7组(AS、YN、BS、AS+YN、AS+BS、YN+BS和AS+YN+BS),分析絮团形态结构差异,评估出对模拟养殖尾水氮去除效果及微生物群落结构优势的最佳组合,最终收集最佳组合絮团烘干研磨成粉末添加到商业饲料制粒,分成对照组和絮团组两组,探讨对胡子鲶的生长性能、饲料利用率、肌肉营养成分及肝脏的消化酶和免疫酶活性的影响。结果表明:YN+BS组水质净化效果稳定,总氮去除效果(89.6%)良好,氨氮、亚硝酸盐和硝酸盐积累低,具有良好的絮团生成量(9.0 ml/L)及占据优势(47.5%)的反硝化菌群(包括Hydrogenophaga、Flavobacterium、Pseudoxanthomonas、Burkholderiaceae、Comamonas、Acinetobacter等)。该组絮团粉以5%比例与商业饲料混合、研磨加工制粒后用于胡子鲶养殖,发现胡子鲶生长性能[包括存活率:(100±0.00)%>(95±0.00)%;增重:(2.81±0.35)g>(2.52±0.52)g;体长增加(1.68±0.36)cm>(1.51±0.34)cm]和饲料系数55±0.03>46±0.12均优于纯商业饲料的对照组,然而在淀粉酶等消化酶、免疫酶包括过氧化氢酶、总超氧化物歧化物、谷胱氨酸过氧化物酶等及肌肉营养成分包括谷氨酸、天冬氨酸、丙氨酸和甘氨酸等鲜味氨基酸上均低于对照组。YN+BS组絮团饲料在生长性能占据优势,然而在消化能力、免疫活性及肌肉营养成分上并未表现出明显优势,需要进一步调整水平絮团添加水平以优化胡子鲶饲养效果。

DNB去除地浸铀矿山污染地下水中NO_3^-的研究

针对地浸铀矿山污染地下水,开展了溶液pH、ρ(COD)/ρ(NO3-)、不同碳源及温度等因素对反硝化细菌(DNB)去除地浸铀矿山污染地下水中NO3-的影响研究。研究结果表明,DNB去除NO3-最适宜的pH为6~8,pH≤5时NO3-的去除率明显下降,随着NO3-去除过程的进行,溶液趋于中性;ρ(COD)/ρ(NO3-)≥1时,NO3-的去除率可达到90%以上,ρ(COD)/ρ(NO3-)<1时,DNB脱氮受到抑制,适宜的ρ(COD)/ρ(NO3-)为1~1.5;碳源影响DNB脱氮速率,乳酸钠、甲醇、乙酸3种碳源中乳酸钠效果最好;氧化还原电位在-50^-200 mV时,电位绝对值越大DNB脱氮速率越快;溶解氧(DO)对DNB去除NO3-影响较大,(ρDO)<1 mg/L时,DNB脱氮进行顺利;温度对DNB去除NO3-效果影响较大,温度高,DNB去除NO3-速度快,当温度为17℃时,DNB对NO3-仍能保持较好的去除效果。

一株适用于短程反硝化的细菌筛选及其脱氮特性

从水稻田土壤中筛选出一株短程反硝化作用明显的菌株D5,结合细菌的形态结构以及16S rDNA序列分析,鉴定为肺炎克雷伯氏杆菌(Klebsiella pneumoniae),并进一步采用单因素实验方法探究了环境因子(碳源种类、C/N和温度)对该菌株脱氮性能的影响。结果表明,多种环境因子均对菌株D5的短程反硝化效果具有较大影响,最佳碳源为柠檬酸钠,最佳C/N为3,最佳温度为25℃和30℃。结果显示,菌株D5具有优良的短程反硝化性能,通过调控环境条件可以取得最佳的短程反硝化效果。

零价铁协同DNB联动去除铀矿污染地下水中的NO_3^-

针对地浸采铀矿山退役采区受污染的地下水,设计了零价铁协同DNB联动工艺去除地下水中的NO3-。污染地下水经中和处理后,进液NO3-的质量浓度为870 mg/L,pH值为6.5～7.5,18℃时DNB反应器的最小碳氮质量比为0.8～1.0,处理量为12 L/h,NO3-的去除率为85%,单位体积生物反应器的处理能力为16.8 L/h。进液流量增大至20 L/h时,NO3-在DNB反应器出现了穿透,但零价铁反应柱可将NO3-去除。采用联动装置最大处理污染地下水量为120 L/h,NO3-负荷可达12～14 kg/(m3.h)。该工艺可有效地去除地浸铀矿山污染地下水中的NO3-,处理效率较高。

1株反硝化细菌的筛选鉴定及其基于响应面法的脱氮条件优化

从污水处理厂采集的污泥样品中分离、筛选出1株具有较高好氧反硝化性能的菌株,命名为X_(3)。通过菌落形态特征、染色特征观察以及16S rDNA分子鉴定,初步确定该菌株为赤红球菌(Rhodococcus ruber)。为了明确该菌株的脱氮特性,通过单因素试验,确定了菌株的最佳碳源为葡萄糖,最佳C/N比为10。利用响应面分析方法考察温度、pH以及转速三个因素相互作用对菌株脱氮能力的影响。研究结果表明,菌株X_(3)在32.24℃,pH为6.65,180.79 r/min为最佳培养条件。最佳条件下培养48 h后,NO_(3)^(-)-N去除率可达96.99%,同时没有NO_(2)^(-)-N的产生。筛选获得的好氧反硝化菌株X_(3)可以作为生物脱氮菌剂开发和相关脱氮机制研究的候选菌株。

基于污水同步脱氮除磷的反硝化聚磷菌的研究与展望

与传统的好氧除磷技术相比,反硝化除磷具有节约碳源、一碳两用、减少污泥产量等优点。综述了反硝化脱氮除磷过程中的主要功能微生物反硝化聚磷菌的培养、分离筛选、电子受体利用等研究的相关进展,总结了近年来研究中常见的反硝化聚磷菌,并对其未来的发展前景做出展望。

异养硝化-好氧反硝化细菌的研究进展及在水产养殖中的应用

异养硝化-好氧反硝化细菌可以同时实现硝化和反硝化,具有高效的脱氮性能,是目前废水生物脱氮处理的研究热点之一。文章从异养硝化-好氧反硝化细菌的研究现状、作用机制、脱氮影响因素、在水产养殖中的应用等4个方面进行了综述,可为异养硝化-好氧反硝化细菌的研究提供理论依据,为异养硝化-好氧反硝化细菌在水产养殖中的应用提供新的思路。

反硝化细菌研究现状和发展态势——基于Web of Science数据库

为解析反硝化细菌的研究进展和动态,基于Web of Science核心数据库,使用VOSviewer、Citespace等工具,分析了1990-2022年反硝化细菌领域研究概况和发展趋势。该领域经历起因、探索、发展三个过程;涉足国家较多但合作关系较弱,欧洲国家区域性合作较强且发文质量较高;中国虽起步晚但发展迅速,发文量多但影响力不够;核心作者中中国彭永臻院士发文最多;核心作者之间合作交流较少。关键词呈现出“工具—对象—方法”三种类型,当前的研究主要关注生物脱氮性能以及致力于提高污废水的脱氮效能。未来的研究更注重在氮氧化物的排放、新型反硝化细菌的筛选及反硝化菌剂的研制和应用、同步硝化反硝化研究以及硝酸盐氮的去除等方面的深化和扩展。

铁屑/竹纤维质量比对竹基耦合体系氮磷同步去除效能的影响

利用铁屑与竹纤维构建竹基耦合体系强化低碳氮比(C/N)废水中氮磷同步去除。采用连续流装置,搭建5组具有不同铁屑/竹纤维质量比(Fe/B)的耦合体系,探究Fe/B对氮磷去除效能的影响。耦合体系在进水平均总氮(TN)为31.32 mg/L,平均C/N为1.16,平均总磷(TP)为2.02 mg/L下连续运行113 d,水力停留时间(HRT)从16 h降至8 h,结果显示Fe/B≤0.500时,耦合体系氮磷去除效果与Fe/B呈正相关;当Fe/B为0.500时,氮磷去除最高,出水TN、TP可达《地表水环境质量标准》(GB 3838—2002)的Ⅳ类标准;Fe/B>0.500时,氮磷去除略有降低;耦合体系出水总铁整体较低,当Fe/B为0.250时,出水总铁波动最大;Fe/B≤0.500时,铁屑可显著促进脱氮除磷功能菌的生长,包括反硝化除磷菌,当Fe/B>0.500时,脱氮除磷功能菌群相对丰度明显降低,菌群结构亦发生显著变化。

反硝化菌种在硝基苯类和苯胺类废水中的应用

在硝基苯类、苯胺类废水处理过程中,污水处理生化系统使用反硝化菌种,可以提高生化系统的反硝化速率,达到提高总氮去除量的目的。结果表明,当生化系统受到高浓总氮污水冲击时,通过投加反硝化菌种以及调整相关工艺,14 d左右即可将出水总氮由约450 mg/L降至200 mg/L以下,达到客户的要求。