岩溶地貌部位对土壤微生物丰度与酶活性的影响

以中国地质科学院岩溶地质研究所桂林丫吉岩溶试验场为研究区,单氨加氧酶的编码基因amoA的部分序列作为氨氧化细菌(AOB)指示基因,利用荧光定量PCR技术,结合平板菌落计数法和土壤酶活性测定,探讨了岩溶地貌部位及土壤成因对微生物群落丰度和酶活性的影响。结果发现,受岩溶地貌部位和土壤成因的影响,土壤酶活性、土壤微生物总数在垭口、坡地、洼地呈增加的趋势,而氨氧化细菌丰度则呈现降低的趋势。结果表明,土壤氨氧化细菌丰度与真菌数呈极其显著的正相关,而与蔗糖酶活性呈极其显著负相关。     

水稻根际和周围土壤中微生物功能基因丰度与碳、氮状况及其通量之间的关系

Rapid nitrogen（N） transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are still unclear. We analyzed different N forms（NH＋4,NO-3, and dissolved organic N）, microbial biomass N and C, dissolved organic C, CH4 and N2O emissions, and abundance of microbial functional genes in both rhizosphere and bulk soils after 37-d rice growth in a greenhouse pot experiment. Results showed that the dissolved organic C was significantly higher in the rhizosphere soil than in the non-rhizosphere bulk soil, but microbial biomass C showed no significant difference. The concentrations of NH＋4, dissolved organic N, and microbial biomass N in the rhizosphere soil were significantly lower than those of the bulk soil, whereas NO-3in the rhizosphere soil was comparable to that in the bulk soil. The CH4 and N2O fluxes from the rhizosphere soil were much higher than those from the bulk soil. Real-time polymerase chain reaction analysis showed that the abundance of seven selected genes, bacterial and archaeal 16 S rRNA genes, amoA genes of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, nosZ gene, mcrA gene, and pmoA gene, was lower in the rhizosphere soil than in the bulk soil, which is contrary to the results of previous studies. The lower concentration of N in the rhizosphere soil indicated that the competition for N in the rhizosphere soil was very strong, thus having a negative effect on the numbers of microbes. We concluded that when N was limiting, the growth of rhizosphere microorganisms depended on their competitive abilities with rice roots for N.     

不同经营强度下毛竹丛枝菌根共生体对氨氧化微生物的影响

利用原位微宇宙试验将丛枝菌根(Arbuscular mycorrhiza,AM)真菌菌丝与根系区分,设置菌根室(RA)和菌丝室(AH)两个分室处理,以粗放经营(extensive management,EM)毛竹林为对照,研究集约经营(Intensive management,IM)条件下毛竹林土壤丛枝菌根共生体对氨氧化微生物群落的影响及其响应机理。结果表明,无论集约经营还是粗放经营AH处理土壤pH均显著降低,且集约经营毛竹林AH处理土壤碱解氮显著降低;不同分室处理对硝化势没有显著影响,但集约经营毛竹林RA处理土壤硝化势显著高于粗放经营;集约经营之后氨氧化古菌(Ammonia-oxidizing archaea,AOA)基因丰度显著降低,而氨氧化细菌(Ammonia-oxidizing bacteria,AOB)基因丰度则在两种经营强度的AH处理中显著降低。不同经营强度和分室处理并未对氨氧化微生物群落组成结构产生显著影响,但网络分析显示集约经营毛竹林氨氧化微生物之间的互作和共生关系优于粗放经营,粗放经营毛竹林氨氧化微生物之间的竞争更为激烈。研究结果为更好地理解毛竹林AM真菌与氨氧化微生物之间的互作关系提供了理论基础。     

高通量测序分析人工养殖成年林麝粪便古菌菌群多样性

本试验的目的是采用高通量测序技术研究人工养殖成年林麝粪便中古菌的结构和组成,并对比不同性别之间的差异。选取12只3岁健康的林麝依据性别分为雄性组(M组)和雌性组(F组),每组各6只。采集其新鲜粪便,提取DNA,用古菌通用引物PCR扩增古菌16S rRNA的V4~V5区,用M i Seq 300 PE测序平台对扩增产物进行高通量测序,用QIIM E等软件对测序序列进行分析统计。结果表明:在从门到属的各级分类水平上,F组与M组古菌的相对丰度差异均不显著(P0.05)。M组和F组的组内遗传距离分别为0.16±0.03和0.27±0.06,组间为0.24±0.07,样品的相似度很高。林麝粪便中的古菌可以分为3个门,优势门为阔古细菌门(Euryarchaeota);在属水平上可以分为7个已知属,优势属为甲烷短杆菌属(Methanobrevibacter),其次为热裸单胞菌属(Thermogymnomonas)。结果提示,雄性和雌性林麝粪便中古菌的结构和组成都没有显著差异,Methanobrevibacter是林麝粪便中的优势古菌属     

A lysimeter study of nitrate leaching from grazed grassland as affected by a nitrification inhibitor,dicyandiamide, and relationships with ammonia oxidizing bacteria and archaea

Nitrate (NO₃^?) can contribute to surface water eutrophication and is deemed harmful to human health if present at high concentrations in the drinking water. In grazed grassland, most of the NO₃^?‐N leaching occurs from animal urine‐N returns. The objective of this study was to determine the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), in decreasing NO₃^? leaching in three different soils from different regions of New Zealand under two different rainfall conditions (1260 mm and 2145 mm p.a.), and explore the relationships between NO₃^?‐N leaching loss and ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA). The DCD nitrification inhibitor was found to be highly effective in decreasing NO₃^?‐N leaching losses from all three soils under both rainfall conditions. Total NO₃^?‐N leaching losses from the urine patch areas were decreased from 67.7–457.0 kg NO₃^?‐N/ha to 29.7–257.4 kg NO₃^?‐N/ha by the DCD treatment, giving an average decrease of 59%. The total NO₃^?‐N leaching losses were not significantly affected by the two different rainfall treatments. The total NO₃^?‐N leaching loss was significantly related to the amoA gene copy numbers of the AOB DNA and to nitrification rate in the soil but not to that of the AOA. These results suggest that the DCD nitrification inhibitor is highly effective in decreasing NO₃^? leaching under these different soil and rainfall conditions and that the amount of NO₃^?‐N leached is mainly related to the growth of the AOB population in the nitrogen rich urine patch soils of grazed grassland.     

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。     

长期施肥对水稻土剖面氨氧化古菌和细菌丰度及组成的影响

长期施肥影响稻田土壤理化性质和硝化微生物群落,但长期施肥对稻田不同土层氨氧化古菌(AOA)和氨氧化细菌(AOB)群落结构的影响尚不明确.以湖南宁乡稻田不同施肥制度长期定位试验为平台,选取不施肥(CK)、施秸秆有机肥(ST)、有机-无机肥配施(OM)和施全量化肥(NPK)4个处理,采用实时荧光定量PCR和Illumina...     

红壤稻田不同生育期土壤氨氧化微生物群落结构

以福建省红壤稻田土壤为对象,通过提取土壤总DNA,利用特异引物进行PCR(聚合酶链反应)扩增和DGGE(变性梯度凝胶电泳)并结合DNA克隆测序,研究了水稻生长过程中稻田土壤氨氧化细菌和氨氧化古菌群落结构的变化。结果显示:稻田土壤具有丰富的氨氧化细菌和氨氧化古菌资源。水稻生长过程中土壤氨氧化细菌群落组成较为稳定,只表现出水稻生长前期(苗期、分蘖期)和中后期(孕穗期、成熟期)间存在一定差异。而土壤氨氧化古菌群落组成变化较大,在水稻生长的苗期、分蘖期、孕穗期和成熟期4个时期间均存在一定差异。在水稻生长过程中,土壤氨氧化细菌群落多样性指数无显著性变化,但氨氧化古菌群落多样性指数随水稻生长明显提高,孕穗期后才达到平稳。水稻生长前期土壤硝化势也具有显著上升趋势,孕穗期时达到最高,而后有所下降。土壤硝化势与氨氧化古菌群落多样性指数具有显著正相关性,与氨氧化细菌没有相关性。研究表明,氨氧化古菌对红壤稻田土壤硝化作用的影响程度较大,证实了氨氧化微生物尤其是氨氧化古菌在稻田土壤微生物组成及其生态系统功能中的重要性。     

藏系绵羊瘤胃古菌季节动态分析

在不同季节分别随机选取3只藏系绵羊,采用PCR-DGGE技术对12只藏系绵羊瘤胃内容物中的细菌区系进行分子生态学分析.对古菌16SrDNA的V2～V4可变区的扩增产物进行DGGE图谱分析、相似性分析和Shannon多样指数分析.结果表明:瘤胃内容物中古菌群落多样性指数冬季与春季间差异不显著(P>0.05),但冬季显著高于夏季(P<0.05),并极显著高于秋季(P<0.01);春季与夏季差异不显著(P>0.05),春季显著高于秋季(P<0.05);夏、秋季之间差异不显著(P>0.05).各季间瘤胃古菌区系组成结构相似性高于94%.冬、春季节,由于牧草中的纤维性物质含量增高,导致瘤胃古菌群落多样性增加,不同季节牧草中粗蛋白和酸性洗涤纤维含量的变化可以引起特异性的古菌群落发育,可能导致不同的优势种群.