scholarly journals Variation in denitrifying bacterial communities along a primary succession in the Hailuogou Glacier retreat area, China

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7356
Author(s):  
Yan Bai ◽  
Xiying Huang ◽  
Xiangrui Zhou ◽  
Quanju Xiang ◽  
Ke Zhao ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Community Composition ◽  
Bacterial Communities ◽  
Primary Succession ◽  
Abiotic Factors ◽  
Bacterial Community Composition ◽  
Living Environment ◽  
Available Phosphorus ◽  
The Tibetan Plateau ◽  
Successional Stages

Background The Hailuogou Glacier is located at the Gongga Mountain on the southeastern edge of the Tibetan Plateau, and has retreated continuously as a result of global warming. The retreat of the Hailuogou Glacier has left behind a primary succession along soil chronosequences. Hailuogou Glacier’s retreated area provides an excellent living environment for the colonization of microbes and plants, making it an ideal model to explore plant successions, microbial communities, and the interaction of plants and microbes during the colonization process. However, to date, the density of the nitrogen cycling microbial communities remain unknown, especially for denitrifiers in the primary succession of the Hailuogou Glacier. Therefore, we investigated the structural succession and its driving factors for denitrifying bacterial communities during the four successional stages (0, 20, 40, and 60 years). Methods The diversity, community composition, and abundance of nosZ-denitrifiers were determined using molecular tools, including terminal restriction fragment length polymorphism and quantitative polymerase chain reactions (qPCR). Results nosZ-denitrifiers were more abundant and diverse in soils from successional years 20–60 compared to 0–5 years, and was highest in Site3 (40 years). The denitrifying bacterial community composition was more complex in older soils (40–60 years) than in younger soils (≤20 years). The terminal restriction fragments (T-RFs) of Azospirillum (90 bp) and Rubrivivax (95 bp) were dominant in soisl during early successional stages (0–20 years) and in the mature phase (40–60 years), respectively. Specific T-RFs of Bradyrhizobium (100 bp) and Pseudomonas (275 bp) were detected only in Site3 and Site4, respectively. Moreover, the unidentified 175 bp T-RFs was detected only in Site3. Of the abiotic factors that were measured in this study, soil available phosphorus, available potassium and denitrifying enzyme activity (DEA) correlated significantly with the community composition of nosZ-denitrifiers (P < 0.05 by Monte Carlo permutation test within RDA analysis).

scholarly journals Variation in the nitrous oxide reductase gene (nosZ)-denitrifying bacterial community in different primary succession stages in the Hailuogou Glacier retreat area, China

2019 ◽  
Author(s):  
Yan Bai ◽  
Xiying Huang ◽  
Xiangrui Zhou ◽  
Quanju Xiang ◽  
Ke Zhao ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Bacterial Community ◽  
Soil Properties ◽  
Bacterial Communities ◽  
Redundancy Analysis ◽  
Primary Succession ◽  
Available Phosphorus ◽  
Nitrous Oxide Reductase ◽  
Reductase Gene ◽  
Successional Stages

Background: The Hailuogou Glacier in the Gongga Mountain region (SW China), on the southeastern edge of the Tibetan Plateau, is well known for its low-elevation modern glaciers. Since the end of the Little Ice Age (LIA), the Hailuogou Glacier has retreated continuously due to global warming, primary vegetation succession and soil chronosequence have developed in this retreat area. The retreated area of Hailuogou Glacier has not been strongly disturbed by human activities, thus it is an ideal models for exploring the biological colonization of nitrogen in the primary successional stages of ecosystem. The nosZ gene encodes the catalytic center of nitrous oxide reductase and is an ideal molecular marker in studying the variation in the denitrifying bacterial community. Methods: Soil properties as well as abundance and composition of the denitrifying bacterial community were determined via chemical analysis, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment length polymorphism (T-RFLP), respectively. The relationships between the nosZ denitrifying bacterial community and soil properties were determined using redundancy analysis (RDA). Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages. Results: Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages. Soil pH in the topsoil decreased from 8.42 to 7.19 in the course of primary succession, while soil organic carbon (SOC) and total nitrogen (TN) gradually increased with primary succession. Available phosphorus (AP) and available potassium (AK), as well as potential denitrify activity (PDA), increased gradually and peaked at the 40-year-old site. The abundance of the nosZ denitrifying bacterial community followed a similar trend. The variation in the denitrifying community composition was complex; Mesorhizobium dominated the soil in the early successional stages (0-20 years) and in the mature phase (60 years), with a relative abundance greater than 55%. Brachybacterium was increased in the 40-year-old site, with a relative abundance of 62.74%, while Azospirillum dominated the early successional stages (0-20 years). Redundancy analysis (RDA) showed that the nosZ denitrifying bacterial community correlated with soil available phosphorus and available potassium levels (P < 0.01).

scholarly journals Variation in the nitrous oxide reductase gene (nosZ)-denitrifying bacterial community in different primary succession stages in the Hailuogou Glacier retreat area, China

2019 ◽  
Author(s):  
Yan Bai ◽  
Xiying Huang ◽  
Xiangrui Zhou ◽  
Quanju Xiang ◽  
Ke Zhao ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Bacterial Community ◽  
Soil Properties ◽  
Bacterial Communities ◽  
Redundancy Analysis ◽  
Primary Succession ◽  
Available Phosphorus ◽  
Nitrous Oxide Reductase ◽  
Reductase Gene ◽  
Successional Stages

Background: The Hailuogou Glacier in the Gongga Mountain region (SW China), on the southeastern edge of the Tibetan Plateau, is well known for its low-elevation modern glaciers. Since the end of the Little Ice Age (LIA), the Hailuogou Glacier has retreated continuously due to global warming, primary vegetation succession and soil chronosequence have developed in this retreat area. The retreated area of Hailuogou Glacier has not been strongly disturbed by human activities, thus it is an ideal models for exploring the biological colonization of nitrogen in the primary successional stages of ecosystem. The nosZ gene encodes the catalytic center of nitrous oxide reductase and is an ideal molecular marker in studying the variation in the denitrifying bacterial community. Methods: Soil properties as well as abundance and composition of the denitrifying bacterial community were determined via chemical analysis, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment length polymorphism (T-RFLP), respectively. The relationships between the nosZ denitrifying bacterial community and soil properties were determined using redundancy analysis (RDA). Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages. Results: Soil properties, potential denitrify activity (PDA), and the nitrous oxide reductase gene (nosZ)-denitrifying bacterial communities significantly differed among successional stages. Soil pH in the topsoil decreased from 8.42 to 7.19 in the course of primary succession, while soil organic carbon (SOC) and total nitrogen (TN) gradually increased with primary succession. Available phosphorus (AP) and available potassium (AK), as well as potential denitrify activity (PDA), increased gradually and peaked at the 40-year-old site. The abundance of the nosZ denitrifying bacterial community followed a similar trend. The variation in the denitrifying community composition was complex; Mesorhizobium dominated the soil in the early successional stages (0-20 years) and in the mature phase (60 years), with a relative abundance greater than 55%. Brachybacterium was increased in the 40-year-old site, with a relative abundance of 62.74%, while Azospirillum dominated the early successional stages (0-20 years). Redundancy analysis (RDA) showed that the nosZ denitrifying bacterial community correlated with soil available phosphorus and available potassium levels (P < 0.01).

scholarly journals Rhizobacterial communities of five co-occurring desert halophytes

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5508 ◽  
Author(s):  
Yan Li ◽  
Yan Kong ◽  
Dexiong Teng ◽  
Xueni Zhang ◽  
Xuemin He ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Plant Species ◽  
Bacterial Communities ◽  
Bacterial Community Composition ◽  
Community Diversity ◽  
Species Identity ◽  
Halostachys Caspica ◽  
Lycium Ruthenicum ◽  
Limonium Gmelinii

BackgroundRecently, researches have begun to investigate the microbial communities associated with halophytes. Both rhizobacterial community composition and the environmental drivers of community assembly have been addressed. However, few studies have explored the structure of rhizobacterial communities associated with halophytic plants that are co-occurring in arid, salinized areas.MethodsFive halophytes were selected for study: these co-occurred in saline soils in the Ebinur Lake Nature Reserve, located at the western margin of the Gurbantunggut Desert of Northwestern China. Halophyte-associated bacterial communities were sampled, and the bacterial 16S rDNA V3–V4 region amplified and sequenced using the Illumina Miseq platform. The bacterial community diversity and structure were compared between the rhizosphere and bulk soils, as well as among the rhizosphere samples. The effects of plant species identity and soil properties on the bacterial communities were also analyzed.ResultsSignificant differences were observed between the rhizosphere and bulk soil bacterial communities. Diversity was higher in the rhizosphere than in the bulk soils. Abundant taxonomic groups (from phylum to genus) in the rhizosphere were much more diverse than in bulk soils. Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and Planctomycetes were the most abundant phyla in the rhizosphere, while Proteobacteria and Firmicutes were common in bulk soils. Overall, the bacterial community composition were not significantly differentiated between the bulk soils of the five plants, but community diversity and structure differed significantly in the rhizosphere. The diversity ofHalostachys caspica,Halocnemum strobilaceumandKalidium foliatumassociated bacterial communities was lower than that ofLimonium gmeliniiandLycium ruthenicumcommunities. Furthermore, the composition of the bacterial communities ofHalostachys caspicaandHalocnemum strobilaceumwas very different from those ofLimonium gmeliniiandLycium ruthenicum. The diversity and community structure were influenced by soil EC, pH and nutrient content (TOC, SOM, TON and AP); of these, the effects of EC on bacterial community composition were less important than those of soil nutrients.DiscussionHalophytic plant species played an important role in shaping associated rhizosphere bacterial communities. When salinity levels were constant, soil nutrients emerged as key factors structuring bacterial communities, while EC played only a minor role. Pairwise differences among the rhizobacterial communities associated with different plant species were not significant, despite some evidence of differentiation. Further studies involving more halophyte species, and individuals per species, are necessary to elucidate plant species identity effects on the rhizosphere for co-occurring halophytes.

scholarly journals Quorum Sensing Regulates the Hydrolytic Enzyme Production and Community Composition of Heterotrophic Bacteria in Coastal Waters

2021 ◽  
Vol 12 ◽  
Author(s):  
Marion Urvoy ◽  
Raphaël Lami ◽  
Catherine Dreanno ◽  
Daniel Delmas ◽  
Stéphane L’Helguen ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Community Composition ◽  
Coastal Waters ◽  
Bacterial Communities ◽  
Heterotrophic Bacteria ◽  
Bacterial Community Composition ◽  
Marine Ecosystem ◽  
Hydrolytic Enzyme ◽  
Enzymatic Activities ◽  
Hydrolytic Activities

Heterotrophic microbial communities play a central role in biogeochemical cycles in the ocean by degrading organic matter through the synthesis of extracellular hydrolytic enzymes. Their hydrolysis rates result from the community’s genomic potential and the differential expression of this genomic potential. Cell-cell communication pathways such as quorum sensing (QS) could impact both aspects and, consequently, structure marine ecosystem functioning. However, the role of QS communications in complex natural assemblages remains largely unknown. In this study, we investigated whether N-acylhomoserine lactones (AHLs), a type of QS signal, could regulate both hydrolytic activities and the bacterial community composition (BCC) of marine planktonic assemblages. To this extent, we carried out two microcosm experiments, adding five different AHLs to bacterial communities sampled in coastal waters (during early and peak bloom) and monitoring their impact on enzymatic activities and diversity over 48 h. Several specific enzymatic activities were impacted during both experiments, as early as 6 h after the AHL amendments. The BCC was also significantly impacted by the treatments after 48 h, and correlated with the expression of the hydrolytic activities, suggesting that changes in hydrolytic intensities may drive changes in BCC. Overall, our results suggest that QS communication could participate in structuring both the function and diversity of marine bacterial communities.

scholarly journals Soil Microbial Biomass and Community Composition Relates to Poplar Genotypes and Environmental Conditions

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 262 ◽  
Author(s):  
Leszek Karliński ◽  
Sabine Ravnskov ◽  
Maria Rudawska
Keyword(s):  
Microbial Biomass ◽  
Microbial Communities ◽  
Community Composition ◽  
Soil Depth ◽  
Abiotic Factors ◽  
Soil Conditions ◽  
Main Role ◽  
Site Factors ◽  
Host Genotype ◽  
The Impact

Poplars, known for their diversity, are trees that can develop symbiotic relationships with several groups of microorganisms. The genetic diversity of poplars and different abiotic factors influence the properties of the soil and may shape microbial communities. Our study aimed to analyse the impact of poplar genotype on the biomass and community composition of the microbiome of four poplar genotypes grown under different soil conditions and soil depths. Of the three study sites, established in the mid-1990s, one was near a copper smelter, whereas the two others were situated in unpolluted regions, but were differentiated according to the physicochemical traits of the soil. The whole-cell fatty acid analysis was used to determine the biomass and proportions of gram-positive, gram-negative and actinobacteria, arbuscular fungi (AMF), other soil fungi, and protozoa in the whole microbial community in the soil. The results showed that the biomass of microorganisms and their contributions to the community of organisms in the soil close to poplar roots were determined by both factors: the tree-host genotype and the soil environment. However, each group of microorganisms was influenced by these factors to a different degree. In general, the site effect played the main role in shaping the microbial biomass (excluding actinobacteria), whereas tree genotype determined the proportions of the fungal and bacterial groups in the microbial communities and the proportion of AMF in the fungal community. Bacterial biomass was influenced more by site factors, whereas fungal biomass more by tree genotype. With increasing soil depth, a decrease in the biomass of all microorganisms was observed; however, the proportions of the different microorganisms within the soil profile were the result of interactions between the host genotype and soil conditions. Despite the predominant impact of soil conditions, our results showed the important role of poplar genotype in shaping microorganism communities in the soil.

scholarly journals Significant Differences in the Gut Bacterial Communities of Hooded Crane (Grus monacha) in Different Seasons at a Stopover Site on the Flyway

Animals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 701 ◽  
Author(s):  
Fengling Zhang ◽  
Xingjia Xiang ◽  
Yuanqiu Dong ◽  
Shaofei Yan ◽  
Yunwei Song ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Communities ◽  
Bacterial Community Structure ◽  
Bacterial Community Composition ◽  
Stopover Site ◽  
Intestinal Bacterial Community ◽  
Hooded Crane ◽  
Grus Monacha

Intestinal bacterial communities form an integral component of the organism. Many factors influence gut bacterial community composition and diversity, including diet, environment and seasonality. During seasonal migration, birds use many habitats and food resources, which may influence their intestinal bacterial community structure. Hooded crane (Grus monacha) is a migrant waterbird that traverses long distances and occupies varied habitats. In this study, we investigated the diversity and differences in intestinal bacterial communities of hooded cranes over the migratory seasons. Fecal samples from hooded cranes were collected at a stopover site in two seasons (spring and fall) in Lindian, China, and at a wintering ground in Shengjin Lake, China. We analyzed bacterial communities from the fecal samples using high throughput sequencing (Illumina Mi-seq). Firmicutes, Proteobacteria, Tenericutes, Cyanobacteria, and Actinobacteria were the dominant phyla across all samples. The intestinal bacterial alpha-diversity of hooded cranes in winter was significantly higher than in fall and spring. The bacterial community composition significantly differed across the three seasons (ANOSIM, P = 0.001), suggesting that seasonal fluctuations may regulate the gut bacterial community composition of migratory birds. This study provides baseline information on the seasonal dynamics of intestinal bacterial community structure in migratory hooded cranes.

scholarly journals Multiple Stressors Determine Community Structure and Estimated Function of River Biofilm Bacteria

2020 ◽  
Vol 86 (12) ◽  
Author(s):  
Ferran Romero ◽  
Vicenç Acuña ◽  
Sergi Sabater
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Communities ◽  
Pesticide Exposure ◽  
Multiple Stressors ◽  
Bacterial Community Composition ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Hydrological Stress ◽  
The Individual

ABSTRACT Freshwater ecosystems are exposed to multiple stressors, but their individual and combined effects remain largely unexplored. Here, we investigated the response of stream biofilm bacterial communities to warming, hydrological stress, and pesticide exposure. We used 24 artificial streams on which epilithic (growing on coarse sediments) and epipsammic (growing on fine sediments) stream biofilms were maintained. Bacterial community composition and estimated function of biofilms exposed during 30 days to individual and combined stressors were assessed using 16S rRNA gene metabarcoding. Among the individual effects by stressors, hydrological stress (i.e., a simulated low-flow situation) was the most relevant, since it significantly altered 57% of the most abundant bacterial taxa (n = 28), followed by warming (21%) and pesticide exposure (11%). Regarding the combined effects, 16% of all stressor combinations resulted in significant interactions on bacterial community composition and estimated function. Antagonistic responses prevailed (57 to 89% of all significant interactions), followed by synergisms (11 to 43%), on specific bacterial taxa, indicating that multiple-stressor scenarios could lead to unexpected shifts in the community composition and associated functions of riverine bacterial communities. IMPORTANCE Freshwater ecosystems such as rivers are of crucial importance for human well-being. However, human activities result in many stressors (e.g., toxic chemicals, increased water temperatures, and hydrological alterations) cooccurring in rivers and streams worldwide. Among the many organisms inhabiting rivers and streams, bacteria are ecologically crucial; they are placed at the base of virtually all food webs and they recycle the organic matter needed for bigger organisms. Most of these bacteria are in close contact with river substratum, where they form the biofilms. There is an urgent need to evaluate the effects of these stressors on river biofilms, so we can anticipate future environmental problems. In this study, we experimentally exposed river biofilms to a pesticide mixture, an increase in water temperature and a simulated low-flow condition, in order to evaluate the individual and joint effects of these stressors on the bacterial community composition and estimated function.

Variation of bacterial communities in Muztagh ice core from 1869 to 2000

2020 ◽  
Author(s):  
Yongqin Liu ◽  
Tandong Yao ◽  
Baiqing Xu
Keyword(s):  
Bacterial Community ◽  
Temporal Variation ◽  
Community Composition ◽  
Bacterial Communities ◽  
Environmental Variables ◽  
Climate Changes ◽  
Bacterial Community Composition ◽  
Ice Core ◽  
The Past ◽  
Stage 1

&lt;p&gt;Many studies focusing on the physical and chemical indicators of the ice core reflected the climate changes. However, only few biological indicators indicated the past climate changes which are mainly focused in biomass rather than diversity. How the biodiversity response to the climate change during the past hundred years is still unknow. Glaciers in Mt. Muztagh Ata region are in&amp;#64258;uenced by the year-round westerly circulation. We firstly disclosed annual variations of bacterial community compositions in ice core over the past 130 years from Muztagh Glacier, the western Tibetan Plateau. Temporal variation in bacterial abundance was strongly controlled by DOC, TN, &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O, Ca&lt;sup&gt;2+&lt;/sup&gt;, SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;, NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; and NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;. Proteobacteria, Actinobacteria and Firmicutes were the three most abundant bacterial phyla, accounting for 49.3%, 21.3% and 11.0% of the total community, respectively. The abundances of Firmicutes and Bacteroidetes pronouncedly increased over time throughout the entire ice core. UPGMA cluster analysis of the bacterial community composition separated the all ice core samples into two main clusters along the temporal variation. The first cluster consisted of samples from 1951 to 2000 and the second cluster contained main samples during the period of 1869-1950. The stage 1 and stage 2 bacterial community dissimilarities increased linearly with time on the basis of the Bray-Curtis distance, indicating a similar temporal&amp;#8211;decay relationship between the stage 1 and stage 2 bacterial communities. Of all the environmental variables examined, only DOC and NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; exhibited very strong negative correlations with bacterial Chao1-richness. &lt;sup&gt;18&lt;/sup&gt;O was another important variable in shaping the ice core bacterial community composition and contributed 1.6% of the total variation. Moreover, DistLM analysis indicated that the environmental variables explained more variation in the stage 1 community (20.1%) than that of the stage 2 community (19.9%).&lt;/p&gt;

scholarly journals Microbial Communities Show Parallels at Sites with Distinct Litter and Soil Characteristics

2011 ◽  
Vol 77 (21) ◽  
pp. 7560-7567 ◽  
Author(s):  
Marketa Sagova-Mareckova ◽  
Marek Omelka ◽  
Ladislav Cermak ◽  
Zdenek Kamenik ◽  
Jana Olsovska ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Community Composition ◽  
Soil Ph ◽  
Soil Chemistry ◽  
High Performance ◽  
Bacterial Community Composition ◽  
Microbial Community Composition ◽  
Carbon Sources ◽  
Soil Extracts

ABSTRACTPlant and microbial community composition in connection with soil chemistry determines soil nutrient cycling. The study aimed at demonstrating links between plant and microbial communities and soil chemistry occurring among and within four sites: two pine forests with contrasting soil pH and two grasslands of dissimilar soil chemistry and vegetation. Soil was characterized by C and N content, particle size, and profiles of low-molecular-weight compounds determined by high-performance liquid chromatography (HPLC) of soil extracts. Bacterial and actinobacterial community composition was assessed by terminal restriction fragment length polymorphism (T-RFLP) and cloning followed by sequencing. Abundances of bacteria, fungi, and actinobacteria were determined by quantitative PCR. In addition, a pool of secondary metabolites was estimated byermresistance genes coding for rRNA methyltransferases. The sites were characterized by a stable proportion of C/N within each site, while on a larger scale, the grasslands had a significantly lower C/N ratio than the forests. A Spearman's test showed that soil pH was correlated with bacterial community composition not only among sites but also within each site. Bacterial, actinobacterial, and fungal abundances were related to carbon sources while T-RFLP-assessed microbial community composition was correlated with the chemical environment represented by HPLC profiles. Actinobacteria community composition was the only studied microbial characteristic correlated to all measured factors. It was concluded that the microbial communities of our sites were influenced primarily not only by soil abiotic characteristics but also by dominant litter quality, particularly, by percentage of recalcitrant compounds.

scholarly journals Application of Methods for Identifying Broiler Chicken Gut Bacterial Species Linked with Increased Energy Metabolism

2007 ◽  
Vol 74 (3) ◽  
pp. 783-791 ◽  
Author(s):  
Valeria A. Torok ◽  
Kathy Ophel-Keller ◽  
Maylene Loo ◽  
Robert J. Hughes
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Community Composition ◽  
Bacterial Species ◽  
Bacterial Community Composition ◽  
Microbial Community Composition ◽  
Metabolizable Energy ◽  
Principal Coordinates ◽  
Improved Performance ◽  
Gut Microbial Community

ABSTRACT A high-throughput microbial profiling tool based on terminal restriction fragment length polymorphism was developed to monitor the poultry gut microbiota in response to dietary manipulations. Gut microbial communities from the duodena, jejuna, ilea, and ceca of 48 birds fed either a barley control diet or barley diet supplemented with exogenous enzymes for degrading nonstarch polysaccharide were characterized by using multivariate statistical methods. Analysis of samples showed that gut microbial communities varied significantly among gut sections, except between the duodenum and jejunum. Significant diet-associated differences in gut microbial communities were detected within the ileum and cecum only. The dissimilarity in bacterial community composition between diets was 73 and 66% within the ileum and cecum, respectively. Operational taxonomic units, representing bacterial species or taxonomically related groups, contributing to diet-associated differences were identified. Several bacterial species contributed to differences between diet-related gut microbial community composition, with no individual bacterial species contributing more than 1 to 5% of the total. Using canonical analysis of principal coordinates biplots, we correlated differences in gut microbial community composition within the ileum and cecum to improved performance, as measured by apparent metabolizable energy. This is the first report that directly links differences in the composition of the gut microbial community with improved performance, which implies that the presence of specific beneficial and/or absence of specific detrimental bacterial species may contribute to the improved performance in these birds.

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