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1.
Sci Total Environ ; 698: 134316, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31783464

RESUMO

Dark carbon fixation (DCF) by chemolithotrophic microbes can make considerable contribution to inorganic carbon fixation in aquatic ecosystems. However, little is known about the importance and diversity of chemolithotrophic microbes in cascade reservoir sediments. In this study, we determined the potential DCF rates of sediments of three cascade reservoirs in Wujiang River basin by carbon isotopic labeling. The results showed that the DCF rates of the surface sediments ranged from 1.5 to 14.7 mmol C m-2 d-1. The ratio of DCF to mineralization rate of sediment organic matter of surface sediment was between 11.6%~60.9%. High-throughput sequencing analysis of cbbL and cbbM genes involved in Calvin Benson Cycle indicated that cbbL-carrying CO2-assimilating bacteria included diverse functional groups, while cbbM type was mostly involved in sulfur oxidation. The sediments of Hongfeng (HF) reservoir, which has much longer hydraulic residence time (HRT) and locates in most upstream of a major tributary of Wujiang River, have substantially higher DCF rates. The cbbL and cbbM communities in HF were dominated by sulfur oxidizing bacteria, and were largely different from that in the other two reservoirs. Our results suggested that chemolithotrophy plays an important role in carbon cycling of sediments in cascade reservoir. Meanwhile, HRT and relative location of cascade reservoirs are the key control factors of both DCF and composition of autotrophic microbial communities in cascade reservoir sediments.


Assuntos
Ciclo do Carbono , Sedimentos Geológicos/microbiologia , Microbiota , China , Fotossíntese
2.
Sci China Life Sci ; 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31686318

RESUMO

Temperature is important to determine physiological status of ectotherms. However, it is still not fully understood how amphibians and their symbiotic microbiota acclimate to ambient temperature. In this study, we investigated the changes of gut microbiota of Xenopus tropicalis at different temperatures under controlled laboratory conditions. The results showed that microbial communities were distinct and shared only a small overlap among froglet guts, culture water and food samples. Furthermore, the dominant taxa harbored in the gut exhibited low relative abundance in water and food. It indicates that bacterial taxa selected by amphibian gut were generally of low abundance in the external environment. Temperature could affect beta-diversity of gut microbiota in terms of phylogenetic distance, but it did not affect alpha diversity. The composition of gut microbiota was similar in warm and cool treatments. However, signature taxa in different temperature environments were identified. The relationships between temperature, gut microbiota and morphology traits of X. tropicalis revealed in this study help us to predict the consequences of environmental changes on ectothermic animals.

3.
Environ Sci Pollut Res Int ; 26(28): 29127-29137, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31392608

RESUMO

Archaea play a vital role in Earth's geochemical cycles, but the factors that drive their distribution between sediments and water-level-fluctuating zones in the East Dongting Lake (EDL) wetland are poorly understood. Here, we used Illumina MiSeq to investigate the variation in the soil archaeal community structure and diversity among sediments and four water-level-fluctuating zones (mudflat, sedge, sedge-Phragmites, and Phragmites) in the EDL wetland. Diverse archaeal assemblages were found in our study, Crenarchaeota, Euryarchaeota, and ammonia-oxidizing and methanogenic subset were the dominant groups, and all their abundances shifted from sediment to water-level-fluctuating zones. The principal coordinates analysis and cluster analysis showed that the overall archaeal community structure was separated into two clusters: cluster I contained nine samples from sediment, mudflat, and sedge zones, whereas cluster II contained six samples from sedge-Phragmites and Phragmites zones. Archaeal diversity was significantly highest in sediment and lowest in Phragmites zone soils. The Mantel test showed that the variation in archaeal community structure was significantly positively correlated with soil water content and pH. The relative abundances of Crenarchaeota and Nitrososphaerales decreased with soil water content, while Euryarchaeota and Methanomicrobiales increased with soil water content. The relative abundance of Methanomicrobiales significantly decreased with pH (R2 = 0.34-0.48). Chao 1, observed operational taxonomic units, Shannon index, and Simpson index all correlated significantly positively with water content (R2 = 0.40-0.60), while Shannon and Simpson indexes both correlated significantly negatively with pH (R2 = 0.20-0.37). Our results demonstrated that the variations in the archaeal community structure were markedly driven by soil water content and pH in the EDL wetland. Our findings suggested that archaeal communities shifted among sediment and four water-level-fluctuating zones, highlighting that the spatiotemporal heterogeneity of greenhouse gas flux in small scale should be taken into account for accurate prediction of greenhouse gas emissions in the Dongting Lake area, especially on the background of climate change and human activities.


Assuntos
Archaea/fisiologia , Sedimentos Geológicos/microbiologia , Microbiologia do Solo , Solo/química , Áreas Alagadas , Amônia/metabolismo , Archaea/genética , Biodiversidade , China , Análise por Conglomerados , Concentração de Íons de Hidrogênio , Lagos , Filogenia , RNA Ribossômico 16S , Água
4.
Front Microbiol ; 9: 2613, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30429841

RESUMO

Fertilizer application has contributed substantially to increasing crop yield. Despite the important role of soil fungi in agricultural production, we still have limited understanding of the complex responses of fungal taxonomic and functional groups to organic and mineral fertilization in long term. Here we report the responses of the fungal communities in an alkaline soil to 30-year application of mineral fertilizer (NP), organic manure (M) and combined fertilizer (NPM) by the Illumina HiSeq sequencing and quantitative real-time PCR to target fungal internal transcribed spacer (ITS) genes. The results show: (1) compared to the unfertilized soil, fertilizer application increased fungal diversity and ITS gene copy numbers, and shifted fungal community structure. Such changes were more pronounced in the M and NPM soils than in the NP soil (except for fungal diversity), which can be largely attributed to the manure induced greater increases in soil total organic C, total N and available P. (2) Compared to the unfertilized soil, the NP and NPM soils reduced the proportion of saprotrophs by 40%, the predominant taxa of which may potentially affect cellulose decomposition. (3) Indicator species analysis suggested that the indicator operational taxonomic units (OTUs) in the M soil occupied 25.6% of its total community, but that only accounted for 0.9% in the NP soil. Our findings suggest that fertilization-induced changes of total fungal community were more responsive to organic manure than mineral fertilizer. The reduced proportion of cellulose decomposition-related saprotrophs in mineral fertilizer treatments may potentially contribute to increasing their soil C stocks.

5.
Sci Rep ; 7(1): 17492, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29235487

RESUMO

How press disturbance (long-term) influences the phylogenetic turnover of soil microbial communities responding to pulse disturbances (short-term) is not fully known. Understanding the complex connections between the history of environmental conditions, assembly processes and microbial community dynamics is necessary to predict microbial response to perturbation. We started by investigating phylogenetic spatial turnover (based on DNA) of soil prokaryotic communities after long-term nitrogen (N) deposition and temporal turnover (based on RNA) of communities responding to pulse by conducting short-term rewetting experiments. The results showed that moderate N addition increased ecological stochasticity and phylogenetic diversity. In contrast, high N addition slightly increased homogeneous selection and decreased phylogenetic diversity. Examining the system with higher phylogenetic resolution revealed a moderate contribution of variable selection across the whole N gradient. The moisture pulse experiment showed that high N soils had higher rates of phylogenetic turnover across short phylogenetic distances and significant changes in community compositions through time. Long-term N input history influenced spatial turnover of microbial communities, but the dominant community assembly mechanisms differed across different N deposition gradients. We further revealed an interaction between press and pulse disturbances whereby deterministic processes were particularly important following pulse disturbances in high N soils.


Assuntos
Nitrogênio , Microbiologia do Solo , Água , Biodiversidade , Nitrogênio/química , Nitrogênio/metabolismo , Filogenia , RNA Ribossômico 16S , Solo/química , Análise Espaço-Temporal , Água/química , Água/metabolismo
6.
FEMS Microbiol Ecol ; 93(12)2017 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-29106508

RESUMO

The mammalian microbial communities in the gastrointestinal tract (GIT) play important roles in host nutrition and health. However, we still lack an understanding of how these communities are organized across GIT in natural environments. Here, using 16S rRNA gene sequencing, we analyzed the bacterial community diversity, network interactions and ecosystem stability across five gut regions (mouth, stomach, small intestine, cecum and colon) emanating from two common pika species in China, including Plateau pikas (Ochotona curzoniae) inhabiting high-altitude regions, as well as Daurian pikas (O. daurica) occupying low-altitude areas. The relative abundances of dominant Bacteroidetes and Firmicutes exhibited an increasing trend from mouth to colon. Cecum and colon harbored higher bacterial diversity compared with other anatomical regions. Gut region significantly influenced the structure of bacterial communities in the GIT. Network analysis indicated that topological features showed marked variations among gut regions. Interestingly, the ecosystem stability of bacterial communities increased gradually from mouth to colon. Our results suggest that gut region influences the diversity, structure and network interactions of bacterial communities in pikas. For hindgut-fermenting herbivorous mammals, relatively higher bacterial diversity and ecosystem stability in the cecum may provide a favorable condition for the fermentation of indigestible plant polysaccharides.


Assuntos
Bacteroidetes/isolamento & purificação , Firmicutes/isolamento & purificação , Microbioma Gastrointestinal/genética , Trato Gastrointestinal/microbiologia , Lagomorpha/microbiologia , Altitude , Animais , Bacteroidetes/classificação , Bacteroidetes/genética , China , Ecossistema , Firmicutes/classificação , Firmicutes/genética , RNA Ribossômico 16S/genética
7.
Biotechnol Biofuels ; 10: 207, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28878822

RESUMO

BACKGROUND: Over three-fifths of the world's known crude oil cannot be recovered using state-of-the-art techniques, but microbial conversion of petroleum hydrocarbons trapped in oil reservoirs to methane is one promising path to increase the recovery of fossil fuels. The process requires cooperation between syntrophic bacteria and methanogenic archaea, which can be affected by sulfate-reducing prokaryotes (SRPs). However, the effects of sulfate on hydrocarbon degradation and methane production remain elusive, and the microbial communities involved are not well understood. RESULTS: In this study, a methanogenic hexadecane-degrading enrichment culture was treated with six different concentrations of sulfate ranging from 0.5 to 25 mM. Methane production and maximum specific methane production rate gradually decreased to 44 and 56% with sulfate concentrations up to 25 mM, respectively. There was a significant positive linear correlation between the sulfate reduction/methane production ratio and initial sulfate concentration, which remained constant during the methane production phase. The apparent methanogenesis fractionation factor (αapp) gradually increased during the methane production phase in each treatment, the αapp for the treatments with lower sulfate (0.5-4 mM) eventually plateaued at ~1.047, but that for the treatment with 10-25 mM sulfate only reached ~1.029. The relative abundance levels of Smithella and Methanoculleus increased almost in parallel with the increasing sulfate concentrations. Furthermore, the predominant sulfate reducer communities shifted from Desulfobacteraceae in the low-sulfate cultures to Desulfomonile in the high-sulfate cultures. CONCLUSION: The distribution of hexadecane carbon between methane-producing and sulfate-reducing populations is dependent on the initial sulfate added, and not affected during the methane production period. There was a relative increase in hydrogenotrophic methanogenesis activity over time for all sulfate treatments, whereas the total activity was inhibited by sulfate addition. Both Smithella and Methanoculleus, the key alkane degraders and methane producers, can adapt to sulfate stress. Specifically, different SRP populations were stimulated at various sulfate concentrations. These results could help to evaluate interactions between sulfate-reducing and methanogenic populations during anaerobic hydrocarbon degradation in oil reservoirs.

8.
J Biotechnol ; 259: 91-94, 2017 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-28774671

RESUMO

n-caproic acid (CA) is a valuable chemical feedstock for various industrial applications. Biological production of CA from renewable carbon sources has attracted a lot of attentions recently. We lately reported the new culture Ruminococcaceae bacterium CPB6, which was isolated from a microbiome for efficient CA production from lactate. To further elucidate its metabolism, we sequenced the whole genome of the strain. The size of the complete genome is 2,069,994bp with 50.58% GC content; no plasmid was identified. Sets of genes involved in the fatty acid biosynthesis via acyl carrier protein (ACP) and coenzyme A (CoA) as well as lactate oxidation/reduction pathways were identified in the genome. These genes were inferred to be correlated with the CA production. The complete genome sequence provides essential information for the elucidation of the metabolism for CA production from lactate, and further improvement of the strain through genetic engineering for enhanced CA production and other biotechnological purposes.


Assuntos
Caproatos/metabolismo , Clostridiales/genética , Clostridiales/metabolismo , Genoma Bacteriano/genética , Ácido Láctico/metabolismo , DNA Bacteriano/análise , DNA Bacteriano/genética , Engenharia Genética , Análise de Sequência de DNA
9.
Water Res ; 123: 134-143, 2017 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-28662395

RESUMO

Temperature plays crucial roles in microbial interactions that affect the stability and performance of anaerobic digestion. In this study, the microbial interactions and their succession in the anaerobic digestion process were investigated at three levels, represented by (1) present and (2) active micro-organisms, and (3) gene expressions under a temperature gradient from 25 to 55 °C. Network topological features indicated a global variation in microbial interactions at different temperatures. The variations of microbial interactions in terms of network modularity and deterministic processes based on topological features, corresponded well with the variations of methane productions, but not with temperatures. A common successional pattern of microbial interactions was observed at different temperatures, which showed that both deterministic processes and network modularity increased over time during the digestion process. It was concluded that the increase in temperature-mediated network modularity and deterministic processes on shaping the microbial interactions improved the stability and efficiency of anaerobic digestion process.


Assuntos
Reatores Biológicos , Interações Microbianas , Temperatura Ambiente , Anaerobiose , Metano
10.
Food Chem ; 218: 534-542, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-27719946

RESUMO

Doubanjiang-meju, a major ingredient of Chinese fermented food for several centuries, is produced using broad bean, wheat flour and salt. In this study, we investigated prokaryotic community succession and metabolite changes using high-throughput sequencing and 1H-NMR methods. After 35 days, bacterial communities, except Lactobacillus and Acinetobacter, were relatively stable until the end of fermentation, and consisted predominantly of the genera Tetragenococcus, Lactobacillus, Staphylococcus, Acinetobacter, Pseudomonas and Streptococcus. Glucose, arabinose, fructose and mannitol were identified as major sugars, lactate and acetate as major organic acids, and amino acids as the major nitrogen compounds present in doubanjiang-meju. Correlation analysis revealed important links between bacterial populations and metabolites, e.g., Pseudomonas was significantly correlated with 10 nitrogenous metabolites, while Streptococcus was significantly correlated with six carbonic metabolite and eight nitrogenous metabolites. These results not only revealed bacterial succession and dynamic changes in metabolites as well as pH and color, but also elucidated their relationships during the doubanjiang-meju fermentation.


Assuntos
Bactérias/metabolismo , Fermentação , Vicia faba/metabolismo , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Vicia faba/microbiologia
11.
Biotechnol Lett ; 39(2): 247-252, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27785595

RESUMO

OBJECTIVE: To reveal the shifts of microbial communities along ammonium gradients, and the relationship between microbial community composition and the anaerobic digestion performance using a high throughput sequencing technique. RESULTS: Methane production declined with increasing ammonium concentration, and was inhibited above 4 g l-1. The volatile fatty acids, especially acetate, accumulated with elevated ammonium. Prokaryotic populations showed different responses to the ammonium concentration: Clostridium, Tepidimicrobium, Sporanaerobacter, Peptostreptococcus, Sarcina and Peptoniphilus showed good tolerance to ammonium ions. However, Syntrophomonas with poor tolerance to ammonium may be inhibited during anaerobic digestion. During methanogenesis, Methanosarcina was the dominant methanogen. CONCLUSION: Excessive ammonium inhibited methane production probably by decoupling the linkage between acidification process and methanogenesis, and finally resulted in different performance in anaerobic digestion.


Assuntos
Compostos de Amônio/farmacologia , Metano/metabolismo , Anaerobiose , Animais , Reatores Biológicos/microbiologia , Ácidos Graxos Voláteis/metabolismo , Esterco/microbiologia , Suínos
12.
Microb Cell Fact ; 15: 96, 2016 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-27260194

RESUMO

BACKGROUND: Temperature is an important factor determining the performance and stability of the anaerobic digestion process. However, the microorganism-regulated mechanisms of temperature effects on the performance of anaerobic digestion systems remain further elusive. To address this issue, we investigated the changes in composition, diversity and activities of microbial communities under temperature gradient from 25 to 55 °C using 16S rRNA gene amplicon sequencing approach based on genomic DNA (refer to as "16S rDNA") and total RNA (refer to as "16S rRNA"). RESULTS: Microbial community structure and activities changed dramatically along the temperature gradient, which corresponded to the variations in digestion performance (e.g., daily CH4 production, total biogas production and volatile fatty acids concentration). The ratios of 16S rRNA to 16S rDNA of microbial taxa, as an indicator of the potentially relative activities in situ, and whole activities of microbial community assessed by the similarity between microbial community based on 16S rDNA and rRNA, varied strongly along the temperature gradient, reflecting different metabolic activities. The daily CH4 production increased with temperature from 25 to 50 °C and declined at 55 °C. Among all the examined microbial properties, the whole activities of microbial community and alpha-diversity indices of both microbial communities and potentially relative activities showed highest correlations to the performance. CONCLUSIONS: The whole activities of microbial community and alpha-diversity indices of both microbial communities and potentially relative activities were sensitive indicators for the performance of anaerobic digestion systems under temperature gradient, while beta-diversity could predict functional differences. Microorganism-regulated mechanisms of temperature effects on anaerobic digestion performance were likely realized through increasing alpha-diversity of both microbial communities and potentially relative activities to supply more functional pathways and activities for metabolic network, and increasing the whole activities of microbial community, especially methanogenesis, to improve the strength and efficiency in anaerobic digestion process.


Assuntos
Bactérias/genética , Anaerobiose , Bactérias/metabolismo , DNA Bacteriano/genética , Análise de Componente Principal , RNA Ribossômico 16S/genética , Temperatura Ambiente
13.
J Biotechnol ; 219: 22-3, 2016 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-26689482

RESUMO

Agarivorans gilvus WH0801(T), an agarase-producing bacterium, was isolated from the surface of seaweed. Here, we present the complete genome sequence, which consists of one circular chromosome of 4,416,600 bp with a GC content of 45.9%. This genetic information will provide insight into biotechnological applications of producing agar for food and industry.


Assuntos
Alteromonadaceae/genética , Glicosídeo Hidrolases/metabolismo , Alga Marinha/microbiologia , Ágar/metabolismo , Alteromonadaceae/isolamento & purificação , Alteromonadaceae/metabolismo , Composição de Bases , Tamanho do Genoma , Genoma Bacteriano , Glicosídeo Hidrolases/genética
14.
Front Microbiol ; 6: 1337, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26648921

RESUMO

The microbial-mediated anaerobic digestion (AD) process represents an efficient biological process for the treatment of organic waste along with biogas harvest. Currently, the key factors structuring bacterial communities and the potential core and unique bacterial populations in manure anaerobic digesters are not completely elucidated yet. In this study, we collected sludge samples from 20 full-scale anaerobic digesters treating cattle or swine manure, and investigated the variations of bacterial community compositions using high-throughput 16S rRNA amplicon sequencing. Clustering and correlation analysis suggested that substrate type and free ammonia (FA) play key roles in determining the bacterial community structure. The COD: [Formula: see text] (C:N) ratio of substrate and FA were the most important available operational parameters correlating to the bacterial communities in cattle and swine manure digesters, respectively. The bacterial populations in all of the digesters were dominated by phylum Firmicutes, followed by Bacteroidetes, Proteobacteria and Chloroflexi. Increased FA content selected Firmicutes, suggesting that they probably play more important roles under high FA content. Syntrophic metabolism by Proteobacteria, Chloroflexi, Synergistetes and Planctomycetes are likely inhibited when FA content is high. Despite the different manure substrates, operational conditions and geographical locations of digesters, core bacterial communities were identified. The core communities were best characterized by phylum Firmicutes, wherein Clostridium predominated overwhelmingly. Substrate-unique and abundant communities may reflect the properties of manure substrate and operational conditions. These findings extend our current understanding of the bacterial assembly in full-scale manure anaerobic digesters.

15.
Biotechnol Biofuels ; 8: 158, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26413157

RESUMO

BACKGROUND: Household biogas digesters are widely used to harvest energy in rural areas of developing countries. Understanding core prokaryotic communities, their co-occurrence patterns, and their relationships to environmental factors is important to manage these small-scale anaerobic digestion systems effectively. In this study, 43 household biogas digesters were collected across eight provinces in China. Prokaryotic communities were investigated using 454 pyrosequencing of 16S rRNA genes. RESULTS: Fourteen core genera and ten core OTUs were identified in household biogas digesters. They were mainly affiliated with the phylum Firmicutes, Synergistetes, Actinobacteria, Chloroflexi, and Spirochaetes. Core prokaryotic genera were mainly composed of Clostridium, Clostridium XI, Syntrophomonas, Cloacibacillus, Sedimentibacter, and Turicibacter. Prokaryotic communities in the 43 samples were clearly divided into two clusters. Cluster I was dominated by Clostridium, while Cluster II was dominated by members of Spirochaetes, Bacteroidales, Clostridia, and abundant syntrophs and methanogens. NH4 (+)-N and COD contributed significantly to the assembly of the prokaryotic community in Cluster I, while NH4 (+)-N, pH, and phosphate contributed significantly to Cluster II. Correlation-based network analysis showed that the prokaryotic communities in the biogas digesters were dominated by some functional modules. Cluster I was dominated by acetotrophic methanogenic modules and the Clostridium-driven primary fermentation module, while the network of Cluster II was dominated by hydrogenotrophic and acetogenic methanogenesis modules and multi-group-driven (Spirochaetes, Bacteroidales, and Clostridia) primary fermentation modules. The network of Cluster II was more complex and functionally redundant. CONCLUSIONS: Prokaryotic communities identified in the household biogas digesters varied significantly and were affected by environmental factors, such as NH4 (+)-N, pH, and COD. However, core prokaryotic communities existed, and most of them were also dominant populations. Cosmopolitan OTUs tended to co-occur. Prokaryotic communities in biogas digesters were well organized by some functional modules. The modular structure of the prokaryotic community, which has functional redundancy, enhances the resistance against environmental stress and maintains digestion efficiency in the anaerobic digestion process.

16.
Appl Environ Microbiol ; 81(17): 6070-7, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26116682

RESUMO

The soil microbial community plays an important role in terrestrial carbon and nitrogen cycling. However, microbial responses to climate warming or cooling remain poorly understood, limiting our ability to predict the consequences of future climate changes. To address this issue, it is critical to identify microbes sensitive to climate change and key driving factors shifting microbial communities. In this study, alpine soil transplant experiments were conducted downward or upward along an elevation gradient between 3,200 and 3,800 m in the Qinghai-Tibet plateau to simulate climate warming or cooling. After a 2-year soil transplant experiment, soil bacterial communities were analyzed by pyrosequencing of 16S rRNA gene amplicons. The results showed that the transplanted soil bacterial communities became more similar to those in their destination sites and more different from those in their "home" sites. Warming led to increases in the relative abundances in Alphaproteobacteria, Gammaproteobacteria, and Actinobacteria and decreases in Acidobacteria, Betaproteobacteria, and Deltaproteobacteria, while cooling had opposite effects on bacterial communities (symmetric response). Soil temperature and plant biomass contributed significantly to shaping the bacterial community structure. Overall, climate warming or cooling shifted the soil bacterial community structure mainly through species sorting, and such a shift might correlate to important biogeochemical processes such as greenhouse gas emissions. This study provides new insights into our understanding of soil bacterial community responses to climate warming and cooling.


Assuntos
Bactérias/isolamento & purificação , Microbiologia do Solo , Altitude , Bactérias/classificação , Bactérias/genética , Mudança Climática , DNA Bacteriano/genética , Ecossistema , Dados de Sequência Molecular , RNA Ribossômico 16S/genética , Tibet
17.
PLoS One ; 9(11): e112609, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25383887

RESUMO

Microbial communities in the rhizosphere make significant contributions to crop health and nutrient cycling. However, their ability to perform important biogeochemical processes remains uncharacterized. Here, we identified important functional genes that characterize the rhizosphere microbial community to understand metabolic capabilities in the maize rhizosphere using the GeoChip-based functional gene array method. Significant differences in functional gene structure were apparent between rhizosphere and bulk soil microbial communities. Approximately half of the detected gene families were significantly (p<0.05) increased in the rhizosphere. Based on the detected gyrB genes, Gammaproteobacteria, Betaproteobacteria, Firmicutes, Bacteroidetes and Cyanobacteria were most enriched in the rhizosphere compared to those in the bulk soil. The rhizosphere niche also supported greater functional diversity in catabolic pathways. The maize rhizosphere had significantly enriched genes involved in carbon fixation and degradation (especially for hemicelluloses, aromatics and lignin), nitrogen fixation, ammonification, denitrification, polyphosphate biosynthesis and degradation, sulfur reduction and oxidation. This research demonstrates that the maize rhizosphere is a hotspot of genes, mostly originating from dominant soil microbial groups such as Proteobacteria, providing functional capacity for the transformation of labile and recalcitrant organic C, N, P and S compounds.


Assuntos
Bactérias/classificação , Bactérias/genética , Zea mays/microbiologia , Perfilação da Expressão Gênica/métodos , Genes Bacterianos , Família Multigênica , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Rizosfera , Microbiologia do Solo
18.
Appl Microbiol Biotechnol ; 98(10): 4771-80, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24633443

RESUMO

Anaerobic co-fermentation of straw and manure is widely used for waste treatment and biogas production. However, the differences between the straw- and slurry-associated prokaryotic communities, their dynamic changes throughout the co-fermentation process, and their correlations with bioreactor performance are not fully understood. To address these questions, we investigated the prokaryotic community compositions and the dynamics of prokaryotes attached to the straw and in the slurry during co-fermentation of wheat straw and swine manure using pyrosequencing technique. The results showed that straw- and slurry-associated prokaryotes were different in their structure and function. Straw-associated prokaryotic communities were overrepresented by the phyla Spirochaetes and Fibrobacteres, while Synergistetes and Euryarchaeota were more abundant in the slurry. The straw-associated candidate class TG3, genera Fibrobacter, Bacteroides, Acetivibrio, Clostridium III, Papillibacter, Treponema, Sedimentibacter, and Lutispora may specialize in substrate hydrolysis. Propionate was the most abundant volatile fatty acid in the slurry, and it was probably degraded through syntrophic oxidation by the genera Pelotomaculum, Methanoculleus, and Methanosaeta. The protein-fermenting bacteria Aminobacterium and Cloacibacillus were much abundant in the slurry, indicating that proteins are important substrates in the co-fermentation. This study provided a better understanding of the anaerobic co-fermentation process that is driven by spatially differentiated microbiota.


Assuntos
Archaea/classificação , Bactérias/classificação , Biota , Esterco/microbiologia , Caules de Planta/microbiologia , Esgotos/microbiologia , Anaerobiose , Animais , Reatores Biológicos/microbiologia , Fermentação , Dados de Sequência Molecular , Oxirredução , Propionatos/metabolismo , Análise de Sequência de DNA , Suínos , Triticum
19.
Appl Environ Microbiol ; 80(7): 2254-60, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24487528

RESUMO

Chinese strong-flavored liquor (CSFL) accounts for more than 70% of all Chinese liquor production. Microbes in pit mud play key roles in the fermentation cellar for the CSFL production. However, microbial diversity, community structure, and cellar-age-related changes in pit mud are poorly understood. Here, we investigated the prokaryotic community structure and diversity in pit-mud samples with different cellar ages (1, 10, 25, and 50 years) using the pyrosequencing technique. Results indicated that prokaryotic diversity increased with cellar age until the age reached 25 years and that prokaryotic community structure changed significantly between three cellar ages (1, 10, and 25 years). Significant correlations between prokaryotic communities and environmental variables (pH, NH4(+), lactic acid, butyric acid, and caproic acid) were observed. Overall, our study results suggested that the long-term brewing operation shapes unique prokaryotic community structure and diversity as well as pit-mud chemistry. We have proposed a three-phase model to characterize the changes of pit-mud prokaryotic communities. (i) Phase I is an initial domestication period. Pit mud is characterized by abundant Lactobacillus and high lactic acid and low pH levels. (ii) Phase II is a transition period. While Lactobacillus abundance decreases dramatically, that of Bacteroidetes and methanogens increases. (iii) Phase III is a relative mature period. The prokaryotic community shows the highest diversity and capability to produce more caproic acid as a precursor for synthesis of ethyl caproate, the main flavor component in CSFL. This research provides scientific evidence to support the practical experience that old fermentation cellars produce high-quality liquor.


Assuntos
Bebidas Alcoólicas/microbiologia , Bactérias/classificação , Bactérias/isolamento & purificação , Biota , China , Fermentação , Dados de Sequência Molecular , Análise de Sequência de DNA , Fatores de Tempo
20.
FEMS Microbiol Ecol ; 83(3): 757-66, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23066709

RESUMO

Methanogenic communities that degrade alkanes have been reported. However, little is known about the key players involved in the process. Methanogenic hexadecane-degrading consortia were enriched from an oilfield (Shengli, China). The microbial dynamics during the transfer incubations were monitored using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of 16S rRNA genes in combination with cloning and sequencing. The archaeal community shifted from a predominance of aceticlastic Methanosaeta during early cultivation to a substantial increase in hydrogenotrophic Methanoculleus in the highly enriched culture. Bacterial T-RFs 161 and 164 bp were consistently detected during the incubation and became dominant in the highly enriched culture. T-RF 161 bp primarily represented uncultured Waste Water of Evry 1 bacterium, which was possibly associated with Candidatus Cloacamonas acidaminovorans (99.7% sequence similarity). T-RF 164 bp could be assigned to both Thermotogaceae, with the closest relative being Candidatus Mesotoga sulfurreducens (similarity of 97%) and Syntrophaceae, with Smithella propionica as the closest relative (similarity of 96-97%). These bacterial lineages were potentially capable of syntrophic interactions with methanogen partners during hexadecane degradation. Partial assA genes (encoding the α-subunit of alkylsuccinate synthase) were also detected, implying that the mechanism of fumarate addition may function in the hexadecane activation.


Assuntos
Alcanos/metabolismo , Bactérias/metabolismo , Euryarchaeota/metabolismo , Consórcios Microbianos , Campos de Petróleo e Gás/microbiologia , Bactérias/classificação , Bactérias/genética , China , DNA Arqueal/genética , DNA Bacteriano/genética , Euryarchaeota/classificação , Euryarchaeota/genética , Metano/metabolismo , Filogenia , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética
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