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1.
Sci Rep ; 10(1): 7842, 2020 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-32398740

RESUMO

The housefly (Musca domestica L.) lives in close association with its microbiota and its symbionts are suggested to have pivotal roles in processes such as metabolism and immune response, but it is unclear how the profound physiological changes during ontogeny affect the housefly's associated microbiota and their metabolic capabilities. The present study applies 16S rRNA gene amplicon sequencing to investigate the development of the host-associated microbiota during ontogeny. The potential for microbiota transfer between developmental stages, and the metabolic potential of these microbiota were evaluated. Representatives of Firmicutes were observed as early colonisers during the larval stages, followed by colonisation by organisms affiliating with Proteobacteria and Bacteroidetes as the flies matured into adults. Microbiota observed across all the developmental stages included Lactococcus, Lactobacillus and Enterococcus, while Weissella and Chishuiella were associated with newly hatched larvae and adults, respectively. Predictive metabolic profiling of the identified microorganisms further suggested that the microbiota and their functional profile mature alongside their host and putative host-microbe relationships are established at different stages of development. The predicted metabolic capability of the microbiota developed from primarily simple processes including carbohydrate and nucleotide metabolisms, to more complex metabolic pathways including amino acid metabolisms and processes related to signal transduction.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32163748

RESUMO

Polyethylene pollutions are considered inert in nature and adversely affect the entire ecosystem. Larvae of greater wax moth (Galleria mellonella) have the ability to masticate and potentially biodegrade polyethylene films at elevated rates. The wax moth has been thought to metabolize PE independently of gut flora, however the role of the microbiome is poorly understood and degradation by the wax moth might be involved. To determine whether the salivary glands of the wax moth were potentially involved in the PE degradation, it was investigated how surface changes of polyethylene were affected by mastication and consumption. Formation of pitting and degradation intermediates including carbonyl groups, indicated that salivary glands could assist in polyethylene degradation. We investigated the biochemical effect of exposure by PE on the composition of the salivary gland proteome. The expression of salivary proteins was found to be affected by PE exposure. The proteins that were significantly affected by the exposure to PE revealed that the wax moth are undergoing general changes in energy levels, also enzymatic pathways associated to fatty acid beta oxidation during consumption to PE were induced.

3.
BMC Genomics ; 21(1): 66, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31964338

RESUMO

BACKGROUND: Houseflies (Musca domestica L.) live in intimate association with numerous microorganisms and is a vector of human pathogens. In temperate areas, houseflies will overwinter in environments constructed by humans and recolonize surrounding areas in early summer. However, the dispersal patterns and associated bacteria across season and location are unclear. We used genotyping-by-sequencing (GBS) for the simultaneous identification and genotyping of thousands of Single Nucleotide Polymorphisms (SNPs) to establish dispersal patterns of houseflies across farms. Secondly, we used 16S rRNA gene amplicon sequencing to establish the variation and association between bacterial communities and the housefly across farms. RESULTS: Using GBS we identified 18,000 SNPs across 400 individuals sampled within and between 11 dairy farms in Denmark. There was evidence for sub-structuring of Danish housefly populations and with genetic structure that differed across season and sex. Further, there was a strong isolation by distance (IBD) effect, but with large variation suggesting that other hidden geographic barriers are important. Large individual variations were observed in the community structure of the microbiome and it was found to be dependent on location, sex, and collection time. Furthermore, the relative prevalence of putative pathogens was highly dependent on location and collection time. CONCLUSION: We were able to identify SNPs for the determination of the spatiotemporal housefly genetic structure, and to establish the variation and association between bacterial communities and the housefly across farms using novel next-generation sequencing (NGS) techniques. These results are important for disease prevention given the fine-scale population structure and IBD for the housefly, and that individual houseflies carry location specific bacteria including putative pathogens.

4.
PLoS One ; 15(1): e0227205, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31951621

RESUMO

OBJECTIVES: Low genetic diversity can lead to reduced average fitness in a population or even extinction. Preserving genetic connectivity across fragmented landscapes is therefore vital to counteract the negative consequences of genetic drift and inbreeding. This study aimed to assess the genetic composition and consequently the conservation status of a nationwide sample of European hedgehogs (Erinaceus europaeus) in Denmark. METHODS: We applied an adaptation of the genotyping by sequencing (GBS) technique to 178 individuals from six geographically distinct populations. We used a Bayesian clustering method to subdivide individuals into genetically distinct populations. We estimated individual observed (iHO), observed (HO), and unbiased expected (uHE) heterozygosity, inbreeding coefficient (FIS), percentage of polymorphic loci (P%) and tested for deviations from Hardy-Weinberg equilibrium (HWE). We used linear models to test for potential anthropogenic effects on the genetic variability of hedgehogs with iHO, uHE, P% and FIS as response variables, and assessed the demographic history of the population. RESULTS: The Danish hedgehog population is composed of three genetic clusters. We found a mean P% of 54.44-94.71, a mean uHE of 0.126-0.318 and a mean HO of 0.124-0.293 in the six populations. The FIS was found to be significantly positive for three of the six populations. We detected a large heterogeneity of iHO values within populations, which can be due to inbreeding and/or fragmentation. FIS values decreased with increasing farmland density, but there was no significant association with human population or road density. CONCLUSIONS: We found a low level of genetic variability and evidence for genetic substructure and low effective population size, which are all consequences of habitat fragmentation. We failed to detect signs of a recent population bottleneck or population increase or decline. However, because the test only identifies recent changes in population size, we cannot reject the possibility of a longer-term decline in the Danish hedgehog population.


Assuntos
Ouriços-Cacheiros/genética , Animais , Teorema de Bayes , Dinamarca , Feminino , Variação Genética , Genética Populacional , Endogamia , Masculino , Polimorfismo de Nucleotídeo Único , Densidade Demográfica
6.
Bioresour Technol ; 291: 121784, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31344638

RESUMO

Biomethanation exploits the ability of methanogenic archaea to convert CO2 and renewable H2 from electrolysis to biomethane. Biofilm reactors are promising for biomethanation scale-up due to high CH4 productivity and low energy input for H2 gas-liquid mass transfer. Effects of operational conditions on biofilm dynamics remain largely uncharacterized but may increase reactor potentials further. This study investigated the effect of hydraulic retention time (HRT) on methanogenic biofilm activity and composition. Commercial carriers floating in liquid were exposed to H2/CO2 for 87 days with the liquid phase being subject to either 18 hours, 10 days, or 20 days HRT. Methanogenic biofilms were dominated by hydrogenotrophic methanogens, but biofilm CH4 productivity was enhanced at 18 hours HRT due to wash-out of competing planktonic species, which otherwise hampered proliferation of biofilm biomass at long HRT. It is suggested that high-rate biofilm reactors can increase methanogenic biofilm activity by minimizing the liquid's H2 exposure.


Assuntos
Biofilmes , Euryarchaeota/fisiologia , Metano/metabolismo , Biomassa , Reatores Biológicos , Plâncton/metabolismo
7.
Chemosphere ; 233: 67-75, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31170585

RESUMO

Ozone (O3) treatment is an effective strategy in maintaining high efficiency and control of biomass accumulation in gas phase biofiltration. However, little is known about the long-term impact of O3 on the microbial communities. In the present study, two biofilters treating gaseous ethyl acetate were operated continuously for 230 days with inlet loads up to 180 g m-3∙h-1. A biofilter operated under continuous O3 addition (90 ppbv) yielded consistently higher removal efficiency (RE) and elimination capacity (EC) compared to the control system. After 120 days of operation, a lower biomass content accompanied by a pH of 1.5 was observed in the ozonated biofilter, which was 2 units lower compared to the control reactor. Both reactors developed a distinct microbial community composition over the course of 230 days. The bacterial community was dominated in both biofilters by Beijerinckia and Gluconacetobacter, while Rhinocladiella similis, Trichosporon veenhuissi and Exophilia oligosperma were abundant in the fungal community. These findings suggest that ozonation of the biofiltration systems not only reduced clogging, but also contributed to the selection of biomass suitable for degradation of ethyl acetate.


Assuntos
Acetatos/química , Poluentes Atmosféricos/química , Ozônio/química , Eliminação de Resíduos Líquidos/métodos , Acetatos/análise , Poluentes Atmosféricos/análise , Bactérias/metabolismo , Biomassa , Reatores Biológicos/microbiologia , Filtração , Microbiota
8.
ISME J ; 13(8): 1933-1946, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30894691

RESUMO

Enhanced biological phosphorus removal (EBPR) is a globally important biotechnological process and relies on the massive accumulation of phosphate within special microorganisms. Candidatus Accumulibacter conform to the classical physiology model for polyphosphate accumulating organisms and are widely believed to be the most important player for the process in full-scale EBPR systems. However, it was impossible till now to quantify the contribution of specific microbial clades to EBPR. In this study, we have developed a new tool to directly link the identity of microbial cells to the absolute quantification of intracellular poly-P and other polymers under in situ conditions, and applied it to eight full-scale EBPR plants. Besides Ca. Accumulibacter, members of the genus Tetrasphaera were found to be important microbes for P accumulation, and in six plants they were the most important. As these Tetrasphaera cells did not exhibit the classical phenotype of poly-P accumulating microbes, our entire understanding of the microbiology of the EBPR process has to be revised. Furthermore, our new single-cell approach can now also be applied to quantify storage polymer dynamics in individual populations in situ in other ecosystems and might become a valuable tool for many environmental microbiologists.


Assuntos
Actinobacteria/isolamento & purificação , Actinobacteria/metabolismo , Hibridização in Situ Fluorescente/métodos , Fósforo/metabolismo , Análise Espectral Raman/métodos , Actinobacteria/classificação , Actinobacteria/genética , Betaproteobacteria/classificação , Betaproteobacteria/genética , Betaproteobacteria/isolamento & purificação , Betaproteobacteria/metabolismo , Biodegradação Ambiental , Reatores Biológicos/microbiologia , Esgotos/microbiologia
9.
Water Res ; 154: 104-116, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30782552

RESUMO

The control of nitrite-oxidizing bacteria (NOB) challenges the implementation of partial nitritation and anammox (PN/A) processes under mainstream conditions. The aim of the present study was to understand how operating conditions impact microbial competition and the control of NOB in hybrid PN/A systems, where biofilm and flocs coexist. A hybrid PN/A moving-bed biofilm reactor (MBBR; also referred to as integrated fixed film activated sludge or IFAS) was operated at 15 °C on aerobically pre-treated municipal wastewater (23 mgNH4-N L-1). Ammonium-oxidizing bacteria (AOB) and NOB were enriched primarily in the flocs, and anammox bacteria (AMX) in the biofilm. After decreasing the dissolved oxygen concentration (DO) from 1.2 to 0.17 mgO2 L-1 - with all other operating conditions unchanged - washout of NOB from the flocs was observed. The activity of the minor NOB fraction remaining in the biofilm was suppressed at low DO. As a result, low effluent NO3- concentrations (0.5 mgN L-1) were consistently achieved at aerobic nitrogen removal rates (80 mgN L-1 d-1) comparable to those of conventional treatment plants. A simple dynamic mathematical model, assuming perfect biomass segregation with AOB and NOB in the flocs and AMX in the biofilm, was able to qualitatively reproduce the selective washout of NOB from the flocs in response to the decrease in DO-setpoint. Similarly, numerical simulations indicated that flocs removal is an effective operational strategy to achieve the selective washout of NOB. The direct competition for NO2- between NOB and AMX - the latter retained in the biofilm and acting as a "NO2-sink" - was identified by the model as key mechanism leading to a difference in the actual growth rates of AOB and NOB (i.e., µNOB < µAOB in flocs) and allowing for the selective NOB washout over a broad range of simulated sludge retention times (SRT = 6.8-24.5 d). Experimental results and model predictions demonstrate the increased operational flexibility, in terms of variables that can be easily controlled by operators, offered by hybrid systems as compared to solely biofilm systems for the control of NOB in mainstream PN/A applications.


Assuntos
Biofilmes , Nitritos , Bactérias , Biomassa , Reatores Biológicos , Nitrogênio , Oxirredução
10.
Environ Res ; 171: 558-567, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30771719

RESUMO

The airborne fungal and bacterial species present in pig farm dust have not been well characterised even though these bioaerosols are known to cause inflammation and other airway maladies. In this study, the microbial species and composition in airborne dust within and between pig farms were investigated. Passively sedimenting dust from six pig farms were collected using electrostatic dust collectors. The bacterial and fungal species were identified using matrix-assisted laser desorption-ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and next generation sequencing (NGS). Dust samples taken within the same stable section revealed high resemblance and stability. Constrained statistical analysis of the microbial community compositions indicated that the types of stable did not appear to have a great effect on the bacterial and fungal ß-diversity. In contrast to this, the farm from which samples were taken appeared to have the greatest effect on the bacterial ß-diversity, but this trend was not observed for the fungal ß-diversity. The most common bacteria and fungi according to NGS data were anaerobes typically associated with the pig intestinal tract and yeasts respectively. Bacterial sedimentation varied at a rate between 103 and 109 CFU/m2/day, with the most common species after aerobic incubation being Aerococcus viridans and Staphylococcus equorum, while Clostridium perfringens and Staphylococcus simulans were the most common species after anaerobic incubation. A total of 28 different species of bacteria and fungi were classifiable as pathogens. In conclusion, the biodiversity in pig farm dust shows a high diversity of bacterial species. However, samples from the same stable section resembled each other, but also different sections within the same farm also resembled each other, thus indicating a high degree of community stability in the dust source. In regards to fungal identification, the biodiversity was observed to be similar between samples from different stable sections and farms, indicating a higher degree of similarities in the mycobiomes found across pig farms studied.


Assuntos
Microbiologia do Ar , Biodiversidade , Poeira , Monitoramento Ambiental , Animais , Bactérias , Fazendas , Fungos , Suínos
11.
PLoS One ; 13(11): e0207382, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30481191

RESUMO

Administrating antibiotics to young piglets may have short- and long-term consequences on the gut microbiota. We hypothesised that these consequences may be alleviated by concurrent probiotic administration. The study objective was to investigate the effect of administrating gentamicin and a mixture of Bacillus (B.) licheniformis, B. subtilis and B. amyloliquefaeceans spores on the gut microbiota of piglets pre- and post-weaning. Twenty-four sows and their litters were randomly allocated to four treatment groups receiving; a) Bacillus spore mixture (six B. subtilis, two B. amyloliquefaeceans, and one B. licheniformis) fed to sows and piglets (PRO); b) gentamicin (5 mg per day) administered to piglets on day 4, 5, and 6 of age (AB); c) Bacillus spore mixture fed to sows and piglets, and gentamicin to piglets (PRO+AB); or d) no administration of probiotics or antibiotics (CTRL). Faecal and digesta samples were collected repeatedly during the study. Selected samples were subjected to 16S rRNA gene sequencing, culture counts, and organic acid, biogenic amine and tissue gene expression analysis. Treatment had a significant effect on the faecal microbial community composition on day 28 and 42, and colonic community on day 28. Faecal species richness (observed and estimated) and Shannon index, and colonic species richness, were higher in AB compared to PRO piglets on day 28, and were not significantly different from day 42. PRO piglets had the highest faecal concentration of iso-butyric acid on day 7 and a higher butyric acid concentration compared to CTRL piglets. We conclude that gentamicin and Bacillus spores influence the gut microbial diversity of piglets, although administration of gentamicin did not result in dysbiosis as hypothesised.


Assuntos
Bacillus/crescimento & desenvolvimento , Microbioma Gastrointestinal/efeitos dos fármacos , Gentamicinas/farmacologia , Probióticos/farmacologia , Esporos Bacterianos/crescimento & desenvolvimento , Animais , Fezes/microbiologia , Distribuição Aleatória , Suínos
12.
Water Res ; 141: 405-416, 2018 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-29859473

RESUMO

A tiered process was developed to assess the transformation, CO2 formation and uptake of four organic micropollutants by carrier-attached microorganisms from two municipal wastewater treatment plants. At the first tier, primary transformation of ibuprofen, naproxen, diclofenac, and mecoprop by carrier-attached microorganisms was shown by the dissipation of the target compounds and the formation of five transformation products using LC-tandem MS. At the second tier, the microbial cleavage of the four organic micropollutants was confirmed with 14C-labeled micropollutants through liquid scintillation counting of the 14CO2 formed. At the third tier, microautoradiography coupled with fluorescence in situ hybridization (MAR-FISH) was used to screen carrier-attached microorganisms for uptake of the four radiolabeled micropollutants. Results from the MAR-FISH screening indicated that only a small fraction of the microbial community (≤1‰) was involved in the uptake of the radiolabeled micropollutants and that the responsible microorganisms differed between the compounds. At the fourth tier, the microbial community structure of the carrier-attached biofilms was analyzed by 16S rRNA gene amplicon sequencing. The sequencing results showed that the MAR-FISH screening targeted ∼80% of the microbial community and that several taxonomic families within the FISH-probed populations with MAR-positive signals (i.e. Firmicutes, Gammaproteobacteria, and Deltaproteobacteria) were present in both biofilms. From the broader perspective of organic micropollutant removal in biological wastewater treatment, the MAR-FISH results of this study indicate a high degree of microbial substrate specialization that could explain differences in transformation rates and patterns between micropollutants and microbial communities.


Assuntos
Ácido 2-Metil-4-clorofenoxiacético/análogos & derivados , Dióxido de Carbono/metabolismo , Diclofenaco/metabolismo , Ibuprofeno/metabolismo , Naproxeno/metabolismo , Poluentes Químicos da Água/metabolismo , Ácido 2-Metil-4-clorofenoxiacético/metabolismo , Biofilmes , Deltaproteobacteria/genética , Deltaproteobacteria/metabolismo , Deltaproteobacteria/fisiologia , Firmicutes/genética , Firmicutes/metabolismo , Firmicutes/fisiologia , Gammaproteobacteria/genética , Gammaproteobacteria/metabolismo , Gammaproteobacteria/fisiologia , Hibridização in Situ Fluorescente , RNA Ribossômico 16S/genética , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Microbiologia da Água
13.
Sci Rep ; 8(1): 5711, 2018 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-29632323

RESUMO

Here we show that a commercial blocking reagent (G2) based on modified eukaryotic DNA significantly improved DNA extraction efficiency. We subjected G2 to an inter-laboratory testing, where DNA was extracted from the same clay subsoil using the same batch of kits. The inter-laboratory extraction campaign revealed large variation among the participating laboratories, but the reagent increased the number of PCR-amplified16S rRNA genes recovered from biomass naturally present in the soils by one log unit. An extensive sequencing approach demonstrated that the blocking reagent was free of contaminating DNA, and may therefore also be used in metagenomics studies that require direct sequencing.


Assuntos
DNA Ribossômico/isolamento & purificação , RNA Ribossômico 16S/isolamento & purificação , Kit de Reagentes para Diagnóstico/normas , Biomassa , Argila , Contaminação por DNA , DNA Ribossômico/genética , Laboratórios , Metagenômica , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Microbiologia do Solo
14.
Sci Rep ; 8(1): 2491, 2018 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-29410494

RESUMO

Springtails are important members of the soil fauna and play a key role in plant litter decomposition, for example through stimulation of the microbial activity. However, their interaction with soil microorganisms remains poorly understood and it is unclear which microorganisms are associated to the springtail (endo) microbiota. Therefore, we assessed the structure of the microbiota of the springtail Orchesella cincta (L.) using 16S rRNA gene amplicon sequencing. Individuals were sampled across sites in the field and the microbiota and in particular the endomicrobiota were investigated. The microbiota was dominated by the families of Rickettsiaceae, Enterobacteriaceae and Comamonadaceae and at the genus level the most abundant genera included Rickettsia, Chryseobacterium, Pseudomonas, and Stenotrophomonas. Microbial communities were distinct for the interior of the springtails for measures of community diversity and exhibited structure according to collection sites. Functional analysis of the springtail bacterial community suggests that abundant members of the microbiota may be associated with metabolism including decomposition processes. Together these results add to the understanding of the microbiota of springtails and interaction with soil microorganisms including their putative functional roles.


Assuntos
Artrópodes/microbiologia , Chryseobacterium/genética , Comamonadaceae/genética , Enterobacteriaceae/genética , Pseudomonas/genética , Rickettsiaceae/genética , Stenotrophomonas/genética , Animais , Biodiversidade , Chryseobacterium/classificação , Chryseobacterium/isolamento & purificação , Chryseobacterium/metabolismo , Comamonadaceae/classificação , Comamonadaceae/isolamento & purificação , Comamonadaceae/metabolismo , DNA Bacteriano/genética , Enterobacteriaceae/classificação , Enterobacteriaceae/isolamento & purificação , Enterobacteriaceae/metabolismo , Microbiota/genética , Pseudomonas/classificação , Pseudomonas/isolamento & purificação , Pseudomonas/metabolismo , RNA Ribossômico 16S/genética , Rickettsiaceae/classificação , Rickettsiaceae/isolamento & purificação , Rickettsiaceae/metabolismo , Análise de Sequência de DNA , Microbiologia do Solo , Stenotrophomonas/classificação , Stenotrophomonas/isolamento & purificação , Stenotrophomonas/metabolismo
15.
Fly (Austin) ; 12(1): 1-12, 2018 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-29095113

RESUMO

Physiological responses to changes in environmental conditions such as temperature may partly arise from the resident microbial community that integrates a wide range of bio-physiological aspects of the host. In the present study, we assessed the effect of developmental temperature on the thermal tolerance and microbial community of Drosophila melanogaster. We also developed a bacterial transplantation protocol in order to examine the possibility of reshaping the host bacterial composition and assessed its influence on the thermotolerance phenotype. We found that the temperature during development affected thermal tolerance and the microbial composition of male D. melanogaster. Flies that developed at low temperature (13°C) were the most cold resistant and showed the highest abundance of Wolbachia, while flies that developed at high temperature (31°C) were the most heat tolerant and had the highest abundance of Acetobacter. In addition, feeding newly eclosed flies with bacterial suspensions from intestines of flies developed at low temperatures changed the heat tolerance of recipient flies. However, we were not able to link this directly to a change in the host bacterial composition.


Assuntos
Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/microbiologia , Acetobacter/crescimento & desenvolvimento , Acetobacter/isolamento & purificação , Animais , Feminino , Microbioma Gastrointestinal , Leuconostoc/crescimento & desenvolvimento , Leuconostoc/isolamento & purificação , Masculino , Temperatura , Wolbachia/crescimento & desenvolvimento , Wolbachia/isolamento & purificação
16.
Waste Manag ; 68: 146-156, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28623019

RESUMO

Biological reduction of CO2 into CH4 by exogenous addition of H2 is a promising technology for upgrading biogas into higher CH4 content. The aim of this work was to study the feasibility of exogenous H2 addition for an in situ biogas upgrading through biological conversion of the biogas CO2 into CH4. Moreover, this study employed systematic study with isotope analysis for providing comprehensive evidence on the underlying pathways of CH4 production and upstream processes. Batch reactors were inoculated with digestate originating from a full-scale biogas plant and fed once with maize leaf substrate. Periodic addition of H2 into the headspace resulted in a completely consumption of CO2 and a concomitant increase in CH4 content up to 89%. The microbial community and isotope analysis shows an enrichment of hydrogenotrophic Methanobacterium and the key role of hydrogenotrophic methanogenesis for biogas upgrading to higher CH4 content. Excess H2 was also supplied to evaluate its effect on overall process performance. The results show that excess H2 addition resulted in accumulation of H2, depletion of CO2 and inhibition of the degradation of acetate and other volatile fatty acids (VFA). A systematic isotope analysis revealed that excess H2 supply led to an increase in dissolved H2 to the level that thermodynamically inhibit the degradation of VFA and stimulate homo-acetogens for production of acetate from CO2 and H2. The inhibition was a temporary effect and acetate degradation resumed when the excess H2 was removed as well as in the presence of stoichiometric amount of H2 and CO2. This inhibition mechanism underlines the importance of carefully regulating the H2 addition rate and gas retention time to the CO2 production rate, H2-uptake rate and growth of hydrogenotrophic methanogens in order to achieve higher CH4 content without the accumulation of acetate and other VFA.


Assuntos
Biocombustíveis , Dióxido de Carbono , Metano , Reatores Biológicos , Euryarchaeota
17.
Bioresour Technol ; 232: 313-320, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28242388

RESUMO

The evolution and population dynamics of complex anaerobic microbial communities in anaerobic digesters were investigated during stable operation and recovery after prolonged starvation. Three thermophilic reactor systems fed with cattle manure were operated continuously in parallel for 167days. Significant changes in the microbial communities were observed for both the bacterial and archaeal populations as the reactor systems were subjected to changing feeding regimes. The ecosystems developed from being relatively similar in structure to more specialised communities, with large population shifts within the acetogenic and methanogenic communities, which appeared to shift towards the hydrogenotrophic methanogenesis pathway. All reactor systems showed signs of adaptation to a harsher environment under high VFA, H2S and ammonia concentrations, but remained at a lower degree of stability after 45days of recovery compared to stable period of operation before starvation.


Assuntos
Reatores Biológicos/microbiologia , Biota/fisiologia , Alimentos , Esterco/microbiologia , Anaerobiose , Animais , Archaea/metabolismo , Bovinos , Sobrevivência Celular , Euryarchaeota/metabolismo , Metano/metabolismo , Viabilidade Microbiana , Dinâmica Populacional
18.
Bioresour Technol ; 233: 256-263, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28285216

RESUMO

Surplus electricity from fluctuating renewable power sources may be converted to CH4 via biomethanisation in anaerobic digesters. The reactor performance and response of methanogen population of mixed-culture reactors was assessed during pulsed H2 injections. Initial H2 uptake rates increased immediately and linearly during consecutive pulse H2 injections for all tested injection rates (0.3 to 1.7LH2/Lsludge/d), while novel high throughput mcrA sequencing revealed an increased abundance of specific hydrogenotrophic methanogens. These findings illustrate the adaptability of the methanogen population to H2 injections and positively affects the implementation of biomethanisation. Acetate accumulated by a 10-fold following injections exceeding a 4:1 H2:CO2 ratio and may act as temporary storage prior to biomethanisation. Daily methane production decreased for headspace CO2 concentrations below 12% and may indicate a high sensitivity of hydrogenotrophic methanogens to CO2 limitation. This may ultimately decide the biogas upgrading potential which can be achieved by biomethanisation.


Assuntos
Biocombustíveis , Metano/biossíntese , Reatores Biológicos , Carbono , Euryarchaeota
19.
PLoS One ; 12(1): e0169753, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28081167

RESUMO

The housefly feeds and reproduces in animal manure and decaying organic substances and thus lives in intimate association with various microorganisms including human pathogens. In order to understand the variation and association between bacteria and the housefly, we used 16S rRNA gene amplicon sequencing to describe bacterial communities of 90 individual houseflies collected within and between ten dairy farms in Denmark. Analysis of gene sequences showed that the most abundant classes of bacteria found across all sites included Bacilli, Clostridia, Actinobacteria, Flavobacteria, and all classes of Proteobacteria and at the genus level the most abundant genera included Corynebacterium, Lactobacillus, Staphylococcus, Vagococcus, Weissella, Lactococcus, and Aerococcus. Comparison of the microbiota of houseflies revealed a highly diverse microbiota compared to other insect species and with most variation in species richness and diversity found between individuals, but not locations. Our study is the first in-depth amplicon sequencing study of the housefly microbiota, and collectively shows that the microbiota of single houseflies is highly diverse and differs between individuals likely to reflect the lifestyle of the housefly. We suggest that these results should be taken into account when addressing the transmission of pathogens by the housefly and assessing the vector competence variation under natural conditions.


Assuntos
Bactérias/classificação , Bactérias/genética , Biodiversidade , Moscas Domésticas/microbiologia , Animais , Bactérias/isolamento & purificação , Fazendas , Microbiota , Filogenia , Análise de Componente Principal , RNA Ribossômico 16S/química , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Análise de Sequência de DNA
20.
Water Res ; 107: 37-46, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27794216

RESUMO

Organic micropollutants (OMPs) such as pharmaceuticals are persistent pollutants that are only partially degraded in waste water treatment plants (WWTPs). In this study, a membrane bioreactor (MBR) system was used as a polishing step on a full-scale WWTP, and its ability to remove micropollutants was examined together with the development and stability of the microbial community. Two stages of operation were studied during a period of 9 months, one with (S1) and one without (S2) the addition of exogenous OMPs. Ibuprofen and naproxen had the highest degradation rates with values of 248 µg/gVSS·h and 71 µg/gVSS·h, whereas diclofenac was a more persistent OMP (7.28 µg/gVSS·h). Mineralization of 14C-labeled OMPs in batch kinetic experiments indicates that higher removal rates (∼0.8 ng/mgTSS·h) with a short lag phase can be obtained when artificial addition of organic micropollutants was performed. Similar microbial populations dominated S1 and S2, despite the independent operations. Hydrogenophaga, Nitrospira, p55-a5, the actinobacterial Tetrasphaera, Propionicimonas, Fodinicola, and Candidatus Microthrix were the most abundant groups in the polishing MBR. Finally, potential microbial candidates for ibuprofen and naproxen degradation are proposed.


Assuntos
Águas Residuárias , Purificação da Água , Reatores Biológicos , Eliminação de Resíduos Líquidos , Água , Poluentes Químicos da Água
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