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.

Impact of acetochlor on ammonia-oxidizing bacteria in microcosm soils

Acetochlor is an increasingly used herbicide on corn in North China. Currently, the effect of acetochlor on soil ammonia-oxidizing bacteria (AOB) communities is not well documented. Here, we studied the diversity and community composition of AOB in soil amended with three concentrations of acetochlor (50, 150, 250 mg/kg) and the control (0 mg acetochlor/kg soil) in a microcosm experiment by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and the phylogenetic analysis of excised ...

Community analysis of ammonia-oxidizing bacteria in activated sludge of eight wastewater treatment systems

We investigated the communities of ammonia-oxidizing bacteria （AOB） in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction （PCR） followed by terminal restriction fragment length polymorphism （T-RFLP）, cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene （amoA）. The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant （WWTP） contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.

Response of ammonia-oxidizing betaproteobacteria to short- term fertilization in a salt marsh in China

This study examines the impacts of short-term(6 months) fertilization on the community structure and abundance of ammonia-oxidizing betaproteobacteria(β-AOB) and the potential nitrification rate in sediment colonized by S uaeda heteroptera in a saltmarsh located in Shuangtai estuary, China. The sediment samples were collected from plots treated with different amounts of an N fertilizer(urea supplied at 0.1, 0.2, 0.4, and 0.8 g/kg(nitrogen content in dry sediment)), and with different forms of N fertilizers(urea,(NH4) 2 SO 4, and NH_4NO_3, each supplied at 0.2 g/kg). The fertilizers were applied 1–4 times during the plant-growing season in May, July, August and September of 2013. Untreated plots were included as a control. As revealed in denaturing gradient gel electrophoresis of the 16 S r RNA gene, the β-AOB community responded to both the amount and form of N. Real-time quantitative PCR indicated that both abundance and potential nitrification rate of β-AOB increased after N addition, regardless of concentration and form(except NH_4NO_3). These results provide evidence that short-term N application influences the sediment β-AOB community, β-AOB abundance and potential nitrification rate in a saltmarsh ecosystem.

Distribution characteristics of ammonia-oxidizing bacteria in the Typha latifolia constructed wetlands using fluorescent in situ hybridization(FISH)

A molecular biology method, fluorescent in situ hybridization（FISH）, in which the pre-treatment was improved in allusion to the media of the constructed wetlands（CW）, e.g. the soil and the grit, was used to investigate the vertical distribution characteristics of ammonia-oxidizing bacteria（AOB） quantity and the relation with oxidation-reduction potential（ORP） in the Typha latifolia constructed wetlands under three different Ioadings in summer from May to September. Results showed that the quantity of the AOB decreased in the Typha latifolia CW with the increase of vertical depth. However, the AOB quantity was 2-4 times the quantity of the control in the root area. Additionally, ORP in the rhizosphere was found to be higher than other areas, which showed that Typha latifolia CW was in an aerobic state in summer when using simulated non-point sewage at the rural area of Taihu Lake in China and small town combined sewage.

Variation of Potential Nitrification and Ammonia-Oxidizing Bacterial Community with Plant-Growing Period in Apple Orchard Soil

In this study, we investigated the potential nitrification and community structure of soil-based ammonia-oxidizing bacteria （AOB） in apple orchard soil during different growth periods and explored the effects of environmental factors on nitrification activity and AOB community composition in the soil of a Hanfu apple orchard, using a culture-dependent technique and denaturing gradient gel electrophoresis （DGGE）. We observed that nitrification activity and AOB abundance were the highest in November, lower in May, and the lowest in July. The results of statistical analysis indicated that total nitrogen （N） content, NH4＋-N content, NO3-N content, and pH showed significant correlations with AOB abundance and nitrification activity in soil. The Shannon-Winner diversity, as well as species richness and evenness indices （determined by PCR-DGGE banding patterns） in soil samples were the highest in September, but the lowest in July, when compared to additional sampled dates. The DGGE fingerprints of soil-based 16S rRNA genes in November were apparently distinct from those observed in May, July, and September, possessing the lowest species richness indices and the highest dominance indices among all four growth periods. Fourteen DGGE bands were excised for sequencing. The resulting analysis indicated that all AOB communities belonged to the 13-Proteobacteria phylum, with the dominant AOB showing high similarity to the Nitrosospira genus. Therefore, soil-based environmental factors, such as pH variation and content of NHa＋-N and NO3--N, can substantially influence the abundance of AOB communities in soil, and play a critical role in soil-based nitrification kinetics.

农田土壤好氧氨氧化和甲烷氧化交互作用机制的研究进展

从农田土壤生态系统中硝化和甲烷氧化的研究意义、氨氧化和甲烷氧化的功能微生物演替规律,以及二者交互作用机制三个方面综述了现阶段取得的主要研究成果,并进一步阐述了土壤碳氮元素生物地球化学循环机制研究的科学问题和面临的挑战。未来研究应充分利用学科交叉,结合宏观结果和土壤微观动态过程,揭示土壤中不可培养微生物代谢能力及其在土壤生物地球化学循环中的重要作用,逐步实现对土壤生态过程的预测和调控。

亚热带森林转换对土壤氮转化关键功能微生物群落的影响

近年来,由于林地开发和商品林建设等原因,我国亚热带地区大量天然林和次生林经皆伐改造为林分结构简单、树种单一的人工林。氮(N)素是维持森林植被生长和系统初级生产力的重要因子,土壤微生物驱动了森林土壤N转化的关键过程。然而,目前亚热带森林转换对土壤N转化微生物群落的影响仍不清晰。以湖南芦头森林生态系统国家定位观测研究站内典型次生林(CS)及由其转换而成的油茶(YC)、黄桃(HT)、杨梅(YM)和杉木(SM)四种人工林为研究对象,采用实时荧光定量PCR和高通量测序等方法,研究了各林分土壤性质、固N菌和氨氧化微生物功能基因丰度、群落特征及相互关系,旨在探讨亚热带森林转换后土壤N转化关键过程(固N和氨氧化作用)的功能微生物群落变化及驱动因素。结果表明:森林转换显著改变了土壤碳(C)、N含量,降低了土壤nifH基因丰度、固N菌和氨氧化细菌的群落α多样性,但提高了氨氧化微生物amoA基因丰度和氨氧化古菌的群落α多样性;并且,森林转换通过改变各功能微生物优势菌群(如变形菌、蓝细菌、泉古菌和奇古菌等)的相对丰度,显著影响了土壤固N菌和氨氧化微生物的群落组成;冗余分析和结构方程模型表明,土壤有机碳、全氮、铵态氮含量和pH是驱动土壤固N菌和氨氧化微生物群落变化的关键因素。森林转换后,合理的施肥方式有利于人工林土壤固N菌和氨氧化微生物的群落恢复。研究结果为转换后单一人工林土壤养分恢复、生产力的提高和可持续经营提供了科学依据。

利用RFLP分析DO对附积床系统中AOB群落结构的影响

为了解析DO浓度对附积床反应器脱氮系统中COD、NH^4＋-N、TN去除效率的影响,以及对氨氧化菌群（AOB）结构及多样性的影响,分析了DO分别为1.0～2.0,2.0～3.0,3.0～4.0mg/L时COD、NH^4＋-N、TN去除效率,并采用针对AOB功能基因氨单加氧酶（amoA）的限制性内切酶片段长度多态性技术（RFLP）分析了三组DO浓度下反应器中AOB的群落结构及多样性.结果表明,不同DO条件下,系统均取得较高的COD和NH^4＋-N的去除效果, NH^4＋-N的去除效率随着DO的增加而提高.不同DO浓度下反应器生物膜上AOB菌群多样性丰富,且与DO对AOB菌群的多样性影响较小相比,DO对AOB的菌群结构及种类的影响较大.

氮源添加对重金属污染土壤氨氧化微生物的影响

矿业活动导致矿区土壤养分流失、土地退化,土壤生态系统敏感且脆弱,恢复过程复杂。其中土壤氮素缺乏是限制该生态系统恢复的主要因子之一。为探讨矿区土壤氮素恢复机制,以广西柳州泗顶矿区重金属污染土壤为研究对象,通过土壤培养实验,采用高通量测序结合荧光定量PCR技术,系统研究了氯化铵(38.114 g∙m^(-1)∙a^(-1)(高浓度)、9.54 g∙m^(-1)∙a^(-1)(低浓度))和尿素(21.43 g∙m^(-1)∙a^(-1)(高浓度)、5.36 g∙m^(-1)∙a^(-1)(低浓度))在不同添加频次(添加12次∙年-1(高频率)和2次∙年-1(低频率))下,对土壤氨氧化古菌(AOA)和氨氧化细菌(AOB)丰度、多样性和群落组成的影响。结果表明,各施氮模式下,amoA-AOB基因丰度显著高于amoA-AOA基因丰度,其丰度范围为(1.56×10^(7)±0.01×10^(7))-(3.58×10^(7)±0.03×10^(7))copies·g^(-1)(氯化铵)和(5.31×10^(7)±0.02×10^(7))-(14.85×10^(7)±0.04×10^(7))copies·g^(-1)(尿素)。AOA群落的ACE、Shannon和Simpson指数均值分别是AOB群落的13.2、1.41和0.627倍,AOA的α-多样性更容易受到不同施氮处理的影响。AOA在门水平上的优势菌门为奇古菌门(Thaumarchaeota)和泉古菌门(Crenarchaeota);在属水平上的优势菌属为亚硝基球菌属(Nitrososphaera)。AOB在门水平上的优势菌门为变形菌门(Proteobacteria);在属水平上的优势菌属为亚硝化螺菌属(Nitrosospira)和亚硝化弧菌属(Nitrosovibrio)。相关性分析表明土壤有效磷是影响amoA-AOB基因丰度的关键因素(p<0.01)。冗余分析表明,微生物量氮是引起AOA群落组成改变的主要因子;而土壤脲酶活性是引起AOB群落组成改变的主要因子。添加氯化铵和尿素使土壤氨氧化潜势和总硝化潜势增加,分别是对照的1.15-3.03倍和2.15-8.55倍,AOB主导土壤中的氨氧化和硝化过程。研究为明确矿区土壤氮循环变化规律,重建矿区土壤氮库提供了理论依据。

有机物对ANAMMOX性能及微生物影响的研究进展

厌氧氨氧化工艺(ANAMMOX)是高效低耗的可持续生物脱氮技术,但厌氧氨氧化菌(AnAOB)世代周期长、对环境因子敏感,有机物作为污水中最常见的物质,对ANAMMOX脱氮有较为复杂的影响。综述了有机物类型、有机物浓度对ANAMMOX脱氮性能及对功能微生物的影响并探讨了原因。有机物分子质量越小、结构越简单,对厌氧氨氧化细菌的影响越显著。在低有机物浓度条件下,AnAOB具有利用简单有机物的多样代谢途径。适当的C/N可促进反硝化菌与AnAOB协同共生,在一定程度上促进AnAOB生长。高浓度有机物易导致反硝化菌占优势,与AnAOB竞争基质,甚至会改变AnAOB正常的代谢途径。醇类对AnAOB有较强的不可逆抑制作用,抗生素和酚类的抑制效果往往是可逆的。Candidatus Brocadia和Candidatus Jettenia对有机物具有相对较好的适应性。理解有机物对AnAOB的影响,可为ANAMMOX的工艺设计和工程应用提供重要参考。

MUCT脱氮除磷系统中聚磷菌(Candidatus Accumulibacter)和氨氧化细菌(AOB)的菌群结构及组成特征

采用MUCT(Modified University of Cape Town)工艺处理低C/N实际生活污水,通过控制溶解氧和缩短水力停留时间(HRT)等手段实现短程硝化,并在短程硝化的基础上取得了良好的反硝化除磷效果。分别采用功能基因ppk1和amo A作为遗传标记对MUCT工艺短程阶段的聚磷菌(Candidatus Accumulibacter)和氨氧化细菌(AOB)的菌群结构进行了研究。ppk1功能基因系统发育分析结果表明,MUCT工艺中Candidatus Accumulibacter分支具有多样化,共包含IID、IIC、IIF 3个进化枝。Candidatus Accumulibacter以TypeⅡ型为主,其中分支Acc-IID占克隆文库的94.3%,是Candidatus Accumulibacter中的优势菌属。证实了在以亚硝酸盐为电子受体的条件下,Acc-IID为除磷的主要承担者。分支Acc-IIF的出现可能与反应系统保持较高温度有关。amo A基因的系统发育分析结果表明,所有AOB序列属于Nitrosomonas europaea lineage。通过低溶解氧和短HRT建立的短程是N.europaea lineage成为AOB中优势菌属的重要原因。研究表明,短程反硝化条件下MUCT反应器中的优势Candidatus Accumulibacter和AOB分别为IID和N.europaea lineage,其丰度和菌群结构是影响污水生物除磷和硝化效果的主要因素。

基于荧光定量PCR技术分析草海沉积物中氨氧化古菌和细菌的空间分布特征

【目的】探明贵州草海表层沉积物中氮循环微生物的丰度、群落结构及其分布规律,为研究湖泊沉积物氮循环机理和开展湖泊生态修复提供理论参考。【方法】通过实时荧光定量PCR技术测定不同季节草海表层沉积物中氨氧化古菌(AOA)与氨氧化细菌(AOB)的丰度,同时测定沉积物、间隙水及上覆水体理化因子,分析各环境因子对AOA amoA和AOB amoA的分布影响。【结果】AOA amoA和AOB amoA基因丰度分别为7.81×103~4.11×106 copies/g和3.50×10^(2)~8.11×10^(4) copies/g,amoA拷贝数在各采样区域差异显著,具有空间分布特征,湖岸带AOA amoA与AOB amoA基因丰度较低。草海沉积物中AOA/AOB为2.3~181.4。草海沉积物整体有机质含量为65.57~436.30 g/kg,总磷为3.870~5.640 g/kg,全氮为0.585~1.252 g/kg;间隙水氨氮和硝酸盐氮浓度分别为0.283~2.082 mg/L和0.007~0.060 mg/L。【结论】AOA在草海氨氧化过程发挥主要作用。AOA amoA基因丰度受有机质和总氮影响,AOB amoA基因丰度受溶解氧和总磷影响。

超滤水对厌氧氨氧化菌活性的影响

为了探究不同比例的人工配水、超滤水和沼液含量对厌氧氨氧化菌活性的影响,开展厌氧氨氧化反应试验,在菌群培养中使用不同混合比例的人工配水、超滤水和沼液,观察并比较氨氮和亚硝酸盐氮的转化情况,分析不同水质条件下厌氧氨氧化菌的活性变化。设置5个试验组,其中,1#瓶中加入460 mL人工配水,2#瓶中加入230 mL人工配水+230 mL超滤水,3#瓶中加入460 mL超滤水,4#瓶中加入230 mL超滤水+230 mL沼液,5#瓶中加入460 mL沼液。试验结果显示,在不同试验组中,添加不同比例的超滤水和沼液显著影响厌氧氨氧化菌的活性。2#瓶的氨氮和亚硝酸盐氮转化情况最佳,而在完全添加沼液的5#瓶中,厌氧氨氧化菌的活性明显降低。这凸显超滤水和沼液在厌氧氨氧化反应中对菌群行为的重要性。这些观察结果对于优化和控制污水处理中的厌氧氨氧化反应具有重要意义。未来的研究可进一步探讨超滤水和沼液中特定成分对菌群的影响,以更全面地理解不同水质条件下厌氧氨氧化菌的行为特征。

AOB与AnAOB在不同生物填料上挂膜效果的研究

针对厌氧氨氧化工艺运行过程中污泥流失严重与启动时间长等问题,本研究通过对多种市售生物填料的挂膜实验,筛选适合好氧氨氧化菌与厌氧氨氧化菌挂膜的生物填料.结果表明,当活性污泥中的好氧氨氧化菌菌属为Nitrosomonas时,AQ1聚氨酯立方体填料最适合其挂膜,挂膜成熟时好氧氨氧化速率可以达到(0.81±0.08)mg N/(L·h),挂膜生物量为(0.87±0.14)mg VSS.而更适合厌氧氨氧化菌(Candidatus Kuenenia)挂膜的生物填料为K3环形填料,材质为聚乙烯或者聚丙烯.当厌氧氨氧化菌挂膜成熟时,其厌氧氨氧化速率可以达到(3.27±0.10)mg N/(L·h),挂膜生物量为(2.74±0.40)mg VSS.厌氧氨氧化菌在K3型填料上的挂膜要优于好氧氨氧化菌,其原因是厌氧氨氧化菌分泌的胞外聚合物含量要高于好氧氨氧化菌,而胞外聚合物是形成生物膜的重要因素.

CARD-FISH研究食细菌线虫对氨氧化细菌(AOB)数量的影响

土壤动物与微生物的取食与反馈之间的关系是土壤生态学研究的核心内容之一。通过接种原位的食细菌线虫和微生物群落模拟土壤真实环境,采用CARD-FISH方法来观察食细菌线虫的不同取食密度下,氨氧化细菌(ammonia oxidizing bacteria)数量的动态变化,以揭示土壤食细菌线虫对AOB数量的影响及AOB的反馈强度。结果表明:与单独接种细菌的处理(SB)相比,接种食细菌线虫显著地增加了土壤中AOB的数量,3个不同线虫接种密度处理中AOB数量表现为接种20条g-1干土的处理(SBN20)>接种10条g-1干土的处理(SBN10)>接种40条g-1干土的处理(SBN40)。由于过度取食,SBN40处理中AOB的数量在培养了14d后低于SB处理,且在第28天时显著低于SB处理。接种食细菌线虫显著增加了土壤中NH4+-N和NO3-N的含量,表明食细菌线虫促进了N的矿化和硝化作用。矿化作用增强使得硝化作用的底物NH4+-N显著增加可能是AOB数量显著增多的重要原因之一。

AOB去除炔雌醇的共代谢与硝基化协同作用

采用氨氧化菌Nitrosomonas europaea降解17α-乙炔雌二醇(EE2),考察降解过程中氨氮的作用以及EE2的降解机制.结果表明,N.europaea降解EE2属于共代谢过程,氨氮是共代谢发生的必要条件.氨氧化过程产生的亚硝氮会在酸性条件下将EE2硝基化,反应符合一级动力学模型,降解速率常数与亚硝酸根、H^+及游离亚硝酸浓度成正相关.通过控制pH值大于7.5抑制硝基化反应,证实了N.europaea对EE2的生物降解作用,生物降解反应符合一级动力学模型且降解速率常数为0.0069h^-1.当N.europaea氨氧化反应导致pH值低于7.5时,EE2的去除存在生物降解和硝基化的协同作用,EE2去除符合一级动力学模型且降解速率常数为0.0093h^-1.同时还发现一种未曾报道过的EE2生物降解产物M613,对于其雌激素效应和毒性还需进一步探究.

Gene abundances of AOA,AOB,and anammox controlled by groundwater chemistry of the Pearl River Delta,China

Ammonia-oxidizing archaea(AOA),ammonia-oxidizing bacteria(AOB),and anaerobic ammonia-oxidation(anammox)bacteria are very important contributors to nitrogen cycling in natural environments.Functional gene abundances of these microbes were believed to be well relevant to N-cycling in groundwater systems,especially in the Pearl River Delta(PRD)groundwater with unique high intrinsic ammonia concentrations.In this research,20 sediment samples from two in the PRD were collected for porewater chemistry analysis and quantification of N-cycling related genes,including archaeal and bacterial amoA gene and anammox 16S ribosomal Ribonucleic Acid(rRNA)gene.Quantitative Polymerase Chain Reaction(qPCR)results showed that gene abundances of AOA,AOB,and anammox bacteria ranged from 3.13×10^(5)to 3.21×10^(7),1.83×10^(4)to 2.74×10^(6),and 9.27×10^(4)to 8.96×10^(6)copies/g in the sediment of the groundwater system,respectively.Anammox bacteria and AOA dominated in aquitards and aquifers,respectively,meanwhile,the aquitard-aquifer interfaces were demonstrated as ammonium-oxidizing hotspots in the aspect of gene numbers.Gene abundances of nitrifiers were analyzed with geochemistry profiles.Correlations between gene numbers and environmental variables indicated that the gene abundances were impacted by hydrogeological conditions,and microbial-derived ammonium loss was dominated by AOA in the northwest PRD and by anammox bacteria in the southeast PRD.

Abundance and Community Composition of Ammonia-Oxidizers in Paddy Soil at Different Nitrogen Fertilizer Rates

Ammonia oxidation, the first and rate-limiting step of nitrification, is carried out by both ammonia-oxidizing bacteria （AOB） and ammonia-oxidizing archaea （AOA）. However, the relative importance of AOB and AOA to nitrification in terrestrial ecosystems is not well understood. The aim of this study was to investigate the effect of the nitrogen input amount on abundance and community composition of AOB and AOA in red paddy soil. Soil samples of 10-20 cm （root layer soil） and 0-5 cm （surface soil） depths were taken from a red paddy. Rice in the paddy was fertilized with different rates of N as urea of N1 （75 kg N ha＂ yr-1）, N2 （150 kg N ha~ yrl）, N3 （225 kg N ha1 yrl） and CK （without fertilizers） in 2009, 2010 and 2011. Abundance and community composition of ammonia oxidizers was analyzed by real-time PCR and denaturing gradient gel electrophoresis （DGGE） based on amoA （the unit A of ammonia monooxygenase） gene. Archaeal amoA copies in N3 and N2 were significantly （P〈0.05） higher than those in CK and N1 in root layer soil or in surface soil under tillering and heading stages of rice, while the enhancement in bacterial amoA gene copies with increasing of N fertilizer rates only took on in root layer soil. N availability and soil NO3--N content increased but soil NH4＋-N content didn＇t change with increasing of N fertilizer rates. Otherwise, the copy numbers of archaeal amoA gene were higher （P〈0.05） than those of bacterial amoA gene in root lary soil or in surface soil. Redundancy discriminate analysis based on DGGE bands showed that there were no obvious differs in composition of AOA or AOB communities in the field among different N fertilizer rates. Results of this study suggested that the abundance of ammonia-oxidizers had active response to N fertilizer rates and the response of AOA was more obvious than that of AOB. Similarity in the community composition of AOA or AOB among different N fertilizer rates indicate that the community composition of ammonia-oxidizers was relatively stable in the paddy soil at least in short term for three years.

海水稻根际效应对滨海盐碱地土壤氨氧化微生物的影响

滨海盐碱地的特殊环境严重限制了土壤氮素转化和利用。微生物介导的水稻根际氨氧化过程是盐碱稻田土壤氮循环的关键过程,但限于研究盲点和技术不足,海水稻根际效应对滨海盐碱地土壤氨氧化微生物群落结构的影响仍少有报道。据此,本研究以“海稻86”为研究对象,分别设置低盐浓度(2 g·kg^(-1))和高盐浓度(6 g·kg^(-1))两组处理进行盆栽试验。结果显示:种植海水稻70 d后,高盐和低盐处理根际土壤的pH分别下降了0.82和0.70个单位,土壤有机质(SOM)含量下降了6.41和4.46 g·kg^(-1),腐殖质(HU)含量提高了5.76和4.45 g·kg^(-1),全氮(TN)含量减少0.46和0.37 g·kg^(-1),表明海水稻可通过降低盐碱地土壤pH,加速有机质分解转化,提高土壤氮循环速率。水稻根际作用可显著提高土壤微生物生物量碳(MBC)、微生物生物量氮(MBN)和微生物呼吸强度,并在种植第55天达到最高,在高盐处理中分别达到850.0 mg·kg^(-1)、72.2 mg·kg^(-1)和231.9 mg·kg^(-1)·d^(-1),低盐处理中达到546.1 mg·kg^(-1)、53.7 mg·kg^(-1)和171.2 mg·kg^(-1)·d^(-1),说明水稻根际作用对土壤微生物数量和活性的影响在55 d最强。海水稻根际效应对滨海盐碱地土壤氨氧化古菌(ammonia-oxidizing archaea,AOA)丰富度、多样性和丰度无显著影响,AOA优势菌为norank_c__environmental_samples_p__Crenarchaeota、unclassified_k__norank_d__Archaea和Nitrososphaera。海水稻根际效应显著提升了滨海盐碱地土壤氨氧化细菌(ammonia-oxidizing bacteria,AOB)丰富度和多样性,提高土壤AOB优势菌environmental_samples_f__Nitrosomonadaceae和Nitrosospira的丰度。相关性分析发现environmental_samples_f__Nitrosomonadaceae和Nitrosospira与土壤pH呈显著负相关,与腐殖质呈显著正相关。本研究结果表明种植海水稻可提高滨海盐碱地养分循环,并且在酸性土壤中耐盐碱水稻根系效应主要影响AOB的群落结构。