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1.
Although molecular techniques are considered to provide a more comprehensive view of species diversity of natural microbial
populations, few studies have compared diversity assessed by molecular and cultivation-based approaches using the same samples.
To achieve this, the diversity of natural populations of ammonia oxidising bacteria in arable soil and marine sediments was
determined by analysis of 16S rDNA sequences from enrichment cultures, prepared using standard methods for this group, and
from 16S rDNA cloned from DNA extracted directly from the same environmental samples. Soil and marine samples yielded 31 and
18 enrichment cultures, respectively, which were compared with 50 and 40 environmental clones. There was no evidence for selection
for particular ammonia oxidizer clusters by different procedures employed for enrichment from soil samples, although no culture
was obtained in medium at acid pH. In soil enrichment cultures, Nitrosospira cluster 3 sequences were most abundant, whereas
clones were distributed more evenly between Nitrosospira clusters 2, 3, and 4. In marine samples, the majority of enrichment
cultures contained Nitrosomonas, whereas Nitrosospira sequences were most abundant among environmental clones. Soil enrichments
contained a higher proportion of identical sequences than clones, suggesting laboratory selection for particular strains,
but the converse was found in marine samples. In addition, 16% of soil enrichment culture sequences were identical to those
in environmental clones, but only 1 of 40 marine enrichments was found among clones, indicating poorer culturability of marine
strains represented in the clone library, under the conditions employed. The study demonstrates significant differences in
species composition assessed by molecular and culture-based approaches but indicates also that, employing only a limited range
of cultivation conditions, 7% of the observed sequence diversity in clones of ammonia oxidizers from these environments could
be obtained in laboratory enrichment culture. Further studies and experimental approaches are required to determine which
approach provides better representation of the natural community. 相似文献
2.
Annabel Meyer Andreas Focks Viviane Radl Gerhard Welzl Ingo Schöning Michael Schloter 《Microbial ecology》2014,67(1):161-166
In the present study, the influence of the land use intensity on the diversity of ammonia oxidizing bacteria (AOB) and archaea (AOA) in soils from different grassland ecosystems has been investigated in spring and summer of the season (April and July). Diversity of AOA and AOB was studied by TRFLP fingerprinting of amoA amplicons. The diversity from AOB was low and dominated by a peak that could be assigned to Nitrosospira. The obtained profiles for AOB were very stable and neither influenced by the land use intensity nor by the time point of sampling. In contrast, the obtained patterns for AOA were more complex although one peak that could be assigned to Nitrosopumilus was dominating all profiles independent from the land use intensity and the sampling time point. Overall, the AOA profiles were much more dynamic than those of AOB and responded clearly to the land use intensity. An influence of the sampling time point was again not visible. Whereas AOB profiles were clearly linked to potential nitrification rates in soil, major TRFs from AOA were negatively correlated to DOC and ammonium availability and not related to potential nitrification rates. 相似文献
3.
Rui Xiao Binze Chen Yongjun Liu Chuanpei Wang Ji-Dong Gu Huyuan Feng 《Geomicrobiology journal》2014,31(7):597-604
Increasing usage of nitrogen fertilizer for food production has resulted in severely environmental problems of nutrients enrichment. This study aimed to examine the response of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) to a long-term nitrogen fertilization in Tibetan alpine meadow. The abundance and composition of both AOB and AOA were assessed using quantitative real-time PCR, cloning and sequencing techniques based on amoA gene under different fertilization gradient (0, 30, 60, 90, and 120 g m?2 year?1). Our results showed that, abundances of AOA amoA genes (ranging from 1.48 × 109 to 2.00 × 109 copies per gram of dry soil) were significantly higher than those of AOB amoA genes (1.25 × 107 to 2.62 × 108 copies per gram of dry soil) under fertilization scenario. The abundance of AOB amoA genes increased with increasing nitrogen fertilization, whereas fertilization had little effect on AOA abundance. Sequences of clone libraries of the different treatments revealed that AOB communities were dominated by representatives of Cluster 4, constituting 48.94–64.44% in each clone library. Sequences of Clusters 9, 1 and 2 were prevalent in soils under higher fertilization. All archaeal amoA sequences recovered were affiliated with the soil/sediment clade and marine sediment clade, and no significant difference was observed on the community structure among different fertilization treatments. Variations in the AOB community structure and abundance were linked to ammonium-N and soil pH induced by different fertilization treatments. These results showed that the abundance and structure of the AOB community respond to the fertilization gradient, not AOA. 相似文献
4.
Dayong Zhao Juan Luo Jianqun Wang Rui Huang Kun Guo Yi Li Qinglong L. Wu 《Current microbiology》2015,70(2):282-289
5.
拉鲁湿地主要植物群落结构及物种多样性 总被引:2,自引:0,他引:2
2002年6~9月对拉鲁湿地植物种类、群落结构、生物量以及物种多样性进行了调查研究.结果表明:(1)拉鲁湿地共有植物30科52属85种,主要有芦苇[Phragmites australis(Cav.)Trin.ex Steud.](A)、尼伯尔酸模(RumexnepalensisSpreng)(B)、水葱(Scirpus validusVahl)(C)、穗状狐尾藻(MyriophyllumspicatumL.)(D)、灯芯草(Juncus effususL.)(E)、针叶苔草(CarexonoeiFranch.et Sav.)和黑褐苔草(CarexatrofuscaSchkuhr)(F)、藏北嵩草(KobresialittledaleiC.B.Clarke)(G)、藏蓟[Cirsiumlanatum(Roxb.ex Willd.)Spreng.](H)等8个主要植物群落.(2)在8个主要植物群落中,嵩草群落所含物种数最多,为44种,穗状狐尾藻群落最少,仅8种;芦苇群落生物量最高,为124.5~1 027.0 g/m2,藏蓟群落生物量最低,为124.5~220.5 g/m2;优势种芦苇的生物量最高,为183.5~660.0 g/m2,藏蓟生物量最低,为43.1~76.3 g/m2.(3)各群落的垂直结构特点是:芦苇群落、水葱群落、穗状狐尾藻群落具有挺水层、浮叶层和沉水层,其他群落只具有可分为高、低两层的草本层.(4)在各群落的相似性方面,嵩草群落与藏蓟群落、水葱群落与芦苇群落和尼伯尔酸模群落的相似性要明显高于其他群落,其Jaccard系数分别为0.549 0、0.538 5、0.500 0;芦苇群落、尼伯尔酸模群落、水葱群落、穗状狐尾藻群落与藏蓟群落以及芦苇群落、穗状狐尾藻群落与嵩草群落在建群种上没有相似之处,Jaccard系数为0. 相似文献
6.
Microbial Population and Activity in Wetland Microcosms Constructed for Improving Treated Municipal Wastewater 总被引:1,自引:0,他引:1
Lilach Iasur-Kruh Yitzhak Hadar Dana Milstein Avital Gasith Dror Minz 《Microbial ecology》2010,59(4):700-709
The idea of using constructed wetlands for the treatment and improving of wastewater emerged in the second half of the last century. Despite relatively wide use of this environmentally friendly technology, relatively little is known about the microbial populations involved in biotransformation and removal of contaminants in this system. The aim of the current study was to investigate the assembly and function of microbial populations in vertical-flow constructed wetland microcosms designed to improve the quality of wastewater after activated sludge treatment. Also, the performance of 3-year-old wetland ponds was investigated. Even though the quality of the influent water was relatively high, improvement in water parameters such as coliform level, ammonia concentration, BOD, and TSS was observed. The performance of the wetland ponds was comparable to that of the microcosms. The microbial community composition of the biofilm formed on the surface of gravel particles in vegetated and plant-free microcosms was studied by denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S rRNA gene fragments. Highly complex bacterial diversity was observed in the biofilm. Cluster analysis of DGGE patterns demonstrated that depth within the wetland microcosm has a stronger effect on microbial community composition of the biofilm formed on wetland matrix than vegetation. Measurements of fluorescein diacetate hydrolysis activity and nitrification potential revealed that hydrolytic activity was affected by both microcosm depth and vegetation presence, whereas nitrification potential was mostly influenced by depth. Resolving the bacterial assemblage of wetland biofilm, which often is considered a black box, will help to understand the interactions involved in the development of diverse and mature biofilm and its function. 相似文献
7.
为分析甘南高寒草甸植物功能群多样性及其物种多度分布对退化的响应,探讨其多样性的形成与维持机制,采用样地调查法收集数据,并使用物种多度模型对其进行拟合分析。结果表明:随着退化程度的加深,植被优势种以禾草科和莎草科植物为主,逐渐变为杂草功能群植物为主,杂草功能群在群落多样性分布中起着主导作用;全部物种多度分布随着退化程度的加深发生变化,其中,无退化草甸的最优拟合模型是VOLKOV,轻度退化草甸的最优拟合模型是GEO,中度退化草甸和重度退化草甸的最优拟合模型为BRO,资源分配模式由随机分配转向固定分配的分配模式;禾草功能群的最优拟合模型以生态位模型为主,资源分配方式由固定分配和随机分配共同主导,豆科功能群的最优拟合模型是BRO,资源分配方式以固定分配为主,杂草功能群的最优拟合模型从中性模型向生态位模型转变,与全部物种多度分布的最优模型基本一致,且资源分配由随机分配向固定分配转变,可以认为杂草功能群是影响群落物种多度分布的主要原因,但是禾草和豆科功能群的贡献也不可忽视。 相似文献
8.
9.
Effects of Arbuscular Mycorrhizas on Ammonia Oxidizing Bacteria in an Organic Farm Soil 总被引:3,自引:0,他引:3
Arbuscular mycorrhizal fungi (AMF) are potentially important in nutrient cycling in agricultural soils and particularly in
soils managed for organic production; little is known, however, about the interrelationships between AMF and other members
of soil microbial communities. Ammonia oxidizing bacteria (AOB) are a trophic group of bacteria having an enormous impact
on nitrogen availability in soils and are expected to be influenced by the presence of AMF. In a field study, we utilized
a unique genetic system comprised of a mycorrhiza defective tomato mutant (named rmc) and its mycorrhiza wild-type progenitor (named 76RMYC+). We examined the effect of AMF by comparing AOB community composition
and populations in soil containing roots of the two tomato genotypes in an organically managed soil. Responses of AOB to soil
N and P amendments were also studied in the same experiment. Phylogenetic analysis of cloned AOB sequences, derived from excised
denaturing gradient gel electrophoresis (DGGE) bands, revealed that the organic farm soil supported a diverse yet stable AOB
community, which was neither influenced by mycorrhizal colonization of roots nor by N and P addition to the soil. Real-time
TaqMan polymerase chain reaction (PCR) was used to quantify AOB population sizes and showed no difference between any of the
treatments. An alternative real-time PCR protocol for quantification of AOB utilizing SYBR green yielded similar results as
the TaqMan real-time PCR method, although with slightly lower resolution. This alternative method is advantageous in not requiring
the detailed background information about AOB community composition required for adaptation of the TaqMan system for a new soil. 相似文献
10.
11.
The relation of glacial microorganism and their living environment is concerned but less understood for both glaciologists and microbiologists. Here we present the results about glacial snow bacteria from 3 glaciers on the Tibetan Plateau. The concentrations and diversity of bacteria collected from snow pit samples of East Rongbuk, Laohugou and Hailuogou glaciers on the Tibetan Plateau were investigated by epifluorescence microscope, denaturing gradient gel electrophoresis and Shannon-Weaver index. Concentrations and community diversity of bacteria in the East Rongbuk glacier with lower concentration and smaller size of microparticle were lower than in the Laohugou with higher concentration and larger size of microparticle. Bacterial concentration in East Rongbuk Glacier was close to that in polar regions, suggesting that Mt. Everest is a bacterial background for remote regions away from direct influence of anthropogenic sources. In addition, altitude difference was another factor for higher concentrations and community diversity of bacteria in Hailuogou and Laohugou glaciers than in East Rongbuk Glacier. The highest concentrations and community diversity of bacteria in Hailuogou Glacier were attributed to its most diverse atmospheric circulations and highest temperature among the 3 glaciers. We suggest a complicated correlation between glacial bacteria and their regional living environments. 相似文献
12.
Species Abundance and Diversity of Burkholderia cepacia Complex in the Environment 总被引:4,自引:0,他引:4 下载免费PDF全文
Despite considerable interest in studying Burkholderia cepacia complex in the environment, we still do not have efficient methods to detect, isolate, and screen large numbers of B. cepacia isolates. To better describe the ecology and diversity of B. cepacia complex, a colony hybridization assay was developed to detect specifically all species of the complex based on polymorphism of the variable V3 region of the 16S rRNA sequence. The sensitivity of the assay was dramatically enhanced by using a probe consisting of three repeats of a B. cepacia complex-specific probe, each separated by a phosphoramidite spacer. In addition, a duplex PCR targeting B. cepacia complex-specific recA and 16S rRNA sequences was developed to enable a fast and reliable diagnostic assay for members of the complex. When applied to maize rhizosphere samples, colony hybridization results were in good agreement with those of most-probable-number duplex PCR, both indicating a >100-fold fluctuation of abundance between individual plants. Using restriction analysis of recA for a total of 285 confirmed isolates of the B. cepacia complex, up to seven B. cepacia complex species were identified; however, their diversity and abundance were not evenly distributed among individual plants, and several allelic variants were commonly found from the same rhizosphere sample. These results indicate that not only complex communities of B. cepacia complex species and closely related strains of the same species may coexist at high population levels but also species composition and abundance may dramatically vary between individual plants. 相似文献
13.
Guofang Liu Xiufang Xie Duo Ye Xuehua Ye Indree Tuvshintogtokh Bayart Mandakh Zhenying Huang Ming Dong 《PloS one》2013,8(10)
Background
The Mongolian steppe is one of the most important grasslands in the world but suffers from aridization and damage from anthropogenic activities. Understanding structure and function of this community is important for the ecological conservation, but has seldom been investigated.Methodology/Principal Findings
In this study, a total of 324 quadrats located on the three main types of Mongolian steppes were surveyed. Early-season perennial forbs (37% of total importance value), late-season annual forbs (33%) and late-season perennial forbs (44%) were dominant in meadow, typical and desert steppes, respectively. Species richness, diversity and plant functional type (PFT) richness decreased from the meadow, via typical to desert steppes, but evenness increased; PFT diversity in the desert and meadow steppes was higher than that in typical steppe. However, above-ground net primary productivity (ANPP) was far lower in desert steppe than in the other two steppes. In addition, the slope of the relationship between species richness and PFT richness increased from the meadow, via typical to desert steppes. Similarly, with an increase in species diversity, PFT diversity increased more quickly in both the desert and typical steppes than that in meadow steppe. Random resampling suggested that this coordination was partly due to a sampling effect of diversity.Conclusions/Significance
These results indicate that desert steppe should be strictly protected because of its limited functional redundancy, which its ecological functioning is sensitive to species loss. In contrast, despite high potential forage production shared by the meadow and typical steppes, management of these two types of steppes should be different: meadow steppe should be preserved due to its higher conservation value characterized by more species redundancy and higher spatial heterogeneity, while typical steppe could be utilized moderately because its dominant grass genus Stipa is resistant to herbivory and drought. 相似文献14.
Abundance and Diversity of Sulfate-Reducing Bacteria in High Arsenic Shallow Aquifers 总被引:1,自引:0,他引:1
Ping Li Bing Li Gordon Webster Yanhong Wang Dawei Jiang Xinyue Dai 《Geomicrobiology journal》2014,31(9):802-812
The abundance, diversity, and relative distribution of sulfate-reducing bacteria (SRB) in high arsenic (As) groundwater aquifers of Hangjinhouqi County in the Hetao Basin, Inner Mongolia was investigated using denaturing gradient gel electrophoresis (DGGE) and quantitative polymerase chain reaction (qPCR) analysis of dsrB genes (encoding dissimilatory sulfite reductase beta-subunit). DGGE results revealed that SRB populations were diverse, but were mainly composed of Desulfotomaculum, Desulfobulbus, Desulfosarcina, and Desulfobacca. The abundance of Desulfobulbus was positively correlated with the ratio of Fe(II)/Fe(III). Although qPCR results showed that the dsrB gene abundance in groundwater samples ranged from below detection to 4.9 × 106 copies/L, and the highest percentage of dsrB gene copies to bacterial 16S rRNA gene copies was 2.1%. Geochemical analyses showed that As(III) content and the ratio of Fe(II) to Fe(III) increased with total As, while sulfate concentrations decreased. Interestingly, the dsrB gene abundance was positively correlated with As concentrations. These results indicate that sulfate reduction occurs simultaneously with As and Fe reduction, and might result in increased As release and mobilization when As is not incorporated into iron sulfides. This study improves our understanding of SRB and As cycling in high As groundwater systems. 相似文献
16.
Agricultural intensification decreases arthropod predator diversity, abundance and population stability, and may affect interactions
between top predators and their arthropod prey – ultimately affecting ecosystem services. Coffee management intensification
(reduction or removal of shade trees) reduces diversity of arthropod predators (ground-foraging ants). Because ants provide
ecosystem services by controlling pests, influences of intensification on arboreal, coffee-foraging ant diversity and abundance
are important. We here address how coffee intensification affects: (1) coffee-foraging ant diversity and abundance and (2)
seasonal fluctuations in ant abundance. In each of four coffee sites of varying management intensity in Chiapas, Mexico, we
sampled vegetation and using two methods, sampled ant diversity and abundance over two years. Sites significantly differed
in vegetation and management intensity. Coffee-foraging ant diversity generally decreased with increasing management intensity
(16–26% fewer species observed in the most intensively-managed site). Ant abundance was higher in the wet season. Management
intensity, however, did not influence ant abundance or seasonal fluctuations in abundance. Our results highlight the importance
of diverse agricultural systems in maintaining arthropod predator diversity, and point to one model system in which we may
effectively test how diversity per se affects ecosystem services. 相似文献
17.
Chao Peng Hongchen Jiang Liuqin Huang Weiguo Hou Jian Yang Shang Wang 《Geomicrobiology journal》2013,30(6):530-539
The cold springs underlain by gas hydrates on the Qinghai-Tibet Plateau (QTP) are similar to deep-sea cold seeps with respect to methane biogeochemistry. Previous studies have shown that ammonia oxidizing bacteria (AOB) and archaea (AOA) are actively present and play important roles in the carbon/nitrogen cycles in cold seeps. Studying AOA and AOB communities in the QTP cold springs will be of great importance to our understanding of carbon and nitrogen cycling dynamics related to the underlying gas hydrates on the QTP. Thus, the abundance and diversity of AOB and AOA in sediments of four cold springs underlain by gas hydrates on the QTP were determined by using quantitative polymerase chain reaction and amoA gene (encoding ammonia monooxygenase involved in ammonia oxidation) phylogenetic analysis. The results showed that the AOB and AOA amoA gene abundances were at 103–104 copies per gram of the sediments in the investigated cold springs. The AOB population consisted of Nitrosospira and Nitrosomonas in contrast with the mere presence of Nitrosospira in marine cold seeps. The AOB diversity was higher in cold springs than in cold seeps. The AOA population was mainly composed of Nitrososphaera, in contrast with the dominance of Nitrosopumilus in cold seeps. The terrestrial origin and high level of dissolved oxygen of the cold springs may be the main factors accounting for the observed differences in AOB and AOA populations between the QTP cold springs and marine cold seeps. 相似文献
18.
19.
Bacteria and nutrients were determined in upper soil samples collected underneath and between canopies of the dominant perennial
in each of three sites along a steep precipitation gradient ranging from the Negev desert in the south of Israel to a Mediterranean
forest in the north. Bacterial abundance, monitored by phospholipid fatty acid analysis, was significantly higher under the
shrub canopy (compared to barren soils) in the arid and semi-arid sites but not in the Mediterranean soils. Bacterial community
composition, determined using terminal restriction fragment length polymorphism and clone libraries, differed according to
the sample’s origin. Closer examination revealed that in the arid and semi-arid sites, α-Proteobacteria are more abundant
under the shrub canopy, while barren soils are characterized by a higher abundance of Actinobacteria. The bacterial communities
in the Mediterranean soils were similar in both patch types. These results correspond to the hypothesis of “resource islands”,
suggesting that shrub canopies provide a resource haven in low-resource landscapes. Yet, a survey of the physicochemical parameters
of inter- and under-shrub soils could not attribute the changes in bacterial diversity to soil moisture, organic matter, or
essential macronutrients. We suggest that in the nutrient-poor soils of the arid and semi-arid sites, bacteria occupying the
soil under the shrub canopy may have longer growth periods under favorable conditions, resulting in their increased biomass
and altered community composition. 相似文献
20.
Diversity and Abundance of Ammonia-Oxidizing Archaea and Bacteria in Diverse Chinese Paddy Soils 总被引:3,自引:0,他引:3
Liuqin Huang Hailiang Dong Shang Wang Qiuyuan Huang Hongchen Jiang 《Geomicrobiology journal》2014,31(1):12-22
Ammonia-oxidizing archaea (AOA) and bacteria (AOB) in three types of paddy soils of China before and after rice plantation were investigated by using an integrated approach including geochemistry, 454 pyrosequencing, and quantitative polymerase chain reaction (PCR). The abundances of AOA amoA gene were 1~2 orders of magnitude higher than AOB amoA gene. The types of paddy soils had important impacts on the diversities of both AOA and AOB via clay mineralogy (smectite or illite-rich) and bioavailability of ammonium. The Nitrososphaera subcluster 5 and Nitrosopumilis cluster of AOA, and Nitrosomonas subcluster 5 and Nitrosospira subcluster 3 of AOB were well adapted to soils with high ammonium concentrations. AOA and AOB community structures were different before and after rice plantation, likely due to changes of pH and ammonium fertilization. The Nitrosospira subclusters 2 and 9 were well adapted to acidic paddy soils. However, the sensitivity of AOA and AOB community structures to these factors may be complicated by other geochemical conditions. The results of this study collectively demonstrated that multiple environmental factors, such as clay mineralogy, ammonium content and total organic carbon as well as soil pH, shaped AOA and AOB community structure and abundance. 相似文献