Previous studies on the Miscellaneous Crenarchaeota Group, recently assigned to the novel archaeal phylum Bathyarchaeota, reported on the dominance of these Archaea within the anaerobic carbohydrate cycle performed by the deep marine biosphere. For the first time, members of this phylum were identified also in mesophilic and thermophilic biogas-forming biofilms and characterized in detail.

Significant quantities of antibiotics are used in modern livestock husbandry and are found in livestock waste. Such waste has been reported to exert inhibitory effects if used as a substrate in biogas facilities. The goal of this study is to analyze the inhibitory effect of the antibiotics chlortetracycline (CTC) and enrofloxacin (EFX) on biogas production with pig slurry. Antibiotic concentrations up to 8,000 mg kg−1 dry matter (DM) pig slurry were added in continuous fermentation tests. Impacts on methane production and on the microbial community structure were analyzed. The results clearly show that chlortetracycline and enrofloxacin negatively affect biogas production. Higher concentrations of antibiotics led to lower methane production. The addition of 200 mg kg−1 DM of CTC or EFX reduced the specific methane yields up to 49 and 44 %, respectively. The microbial community did not show any changes at this concentration. When chlortetracycline was added at a concentration of 8,000 mg kg−1 DM, the biodiversity changed slightly compared to the control without antibiotics.

The aim of this study was to analyze the effect of the addition of rice straw and clay residuals on the prokaryote methane-producing community structure in a semi-continuously stirred tank reactor fed with swine manure. Molecular techniques, including terminal restriction fragment length polymorphism and a comparative nucleotide sequence analyses of the prokaryotic 16S rRNA genes, were performed. The results showed a positive effect of clay addition on methane yield during the co-digestion of swine manure and rice straw. At the digestion of swine manure, the bacterial phylum Firmicutes and the archaeal family Methanosarcinaceae, particularly Methanosarcina species, were predominant. During the co-digestion of swine manure and rice straw the microbial community changed, and with the addition of clay residual, the phylum Bacteroidetes predominated. The new nutritional conditions resulted in a shift in the archaeal family Methanosarcinaceae community as acetoclastic Methanosaeta species became dominant.

In dieser Studie wurde die Entwicklung methanogener Biofilme in meso- und thermophilen ein- und zweistufigen Biogasreaktoren bei der Vergarung von Maissilage untersucht. Ziel war neben der kultivierungsunabhangigen Charakterisierung von Struktur und Dynamik der mikrobiellen Lebensgemeinschaften und ihrer Stoffwechseleigenschaften insbesondere auch die Entwicklung von Strategien zur Ansiedlung solcher Biofilme.

BACKGROUNDHydrodynamic shear plays a major role in the formation, maintenance, structure, and metabolism of self-immobilized microbial communities in reactors. The study attempts to correlate the performance and microbial community structure of granular sludge in a mesophilic hybrid anaerobic reactor under different upflow velocities to fluidize the bed. The reactor was started with an initial upflow velocity of 4mh(-1), which was increased gradually till system deterioration to observe its effect on granule size, reactor performance, and microbial community structure. Monte Carlo method was used to quantify hydrodynamic shear range at different upflow velocities using a modified Ergun equation for the respective ranges of granule size.RESULTSUp to 6mh(-1) performance was positively affected, but beyond this upflow velocity, the system started showing reduced performance and completely deteriorated at 10mh(-1). Significant reduction in the abundance and diversity of both Archaea and Bacteria was observed. Among all methanogenic groups, Methanosaetaceae was most severely affected due to breakage and wash out of granules.CONCLUSIONIt can be concluded that hydrodynamic shear can be employed as a sensitive control parameter to improve reactor performance, and a specified range should be determined experimentally to avoid negative influences associated with this. (c) 2013 Society of Chemical Industry

This study aimed to analyse the effect of sudden temperature increases (in the range of 45-65 degrees C) on the performance and the microbial community structure of a hybrid anaerobic reactor. The reactor recovered with time after every temperature shock up to the operating temperature of 55 degrees C. At 55 degrees C, a 10 degrees C shock resulting in an operating temperature of 65 degrees C, deteriorated the reactor's performance. At this condition, both, the diversity and the relative abundance of methanogenic groups, especially of Methanosaetaceae, were significantly affected as observed by DGGE fingerprinting and quantitative PCR. In contrast, at lower temperatures (i.e., 45 and 55 degrees C), thermal shocks seemed to have less effect due to the presence and maintenance of thermophilic strains, which prevented system deterioration. At 65 degrees C, the absence of any acetoclastic methanogen is assumed to be the cause of system failure. (C) 2014 Elsevier Ltd. All rights reserved.

Some species of the genus Arcobacter are considered to be emerging food pathogens. With respect to recent vegetable-borne outbreaks, the aim of this work was to investigate the occurrence and diversity of Arcobacter within the production chain of a spinach-processing plant by a combination of cultivation and molecular methods. Samples including spinach, water, and surface biofilm were taken over a period of three years from the entire processing line. Ten 16S rRNA (rrs) gene clone libraries were constructed and analysed using amplified rRNA gene restriction analysis (ARDRA). Approximately 1200 clones were studied that resulted in 44 operational taxonomic units (OTUs). Sequences with high similarities to Arcobacter cryaerophilus (13% of clones, 3 OTUs), A. ellisii (4%, 6 OTUs), A. suis (15%, 3 OTUs), and the type strain of A. nitrofigilis (1%, 7 OTUs) were identified. This represents the first report of the detection of the recently described species A. ellisii, A. suis and, in addition, A. venerupis from alternative habitats. A total of 67% of the clones (22 OTUs) could not be assigned to a genus, which indicated the presence of uncharacterised Arcobacter species. For the cultivation-independent detection of Arcobacter, two genus-specific quantitative PCR (qPCR) assays were developed and tested on 15 Arcobacter species. When these assays were applied to samples from the spinach-processing plant, they showed positive results for up to 35% of the samples and supported the conclusion that there is a considerable risk for the transfer of pathogenic Arcobacter species on vegetables, which was also verified by a cultivation approach.

Industrial effluents differ in their organic composition thereby providing different carbon sources to the microbial communities involved in its treatment. This study aimed to investigate the correlation of microbial community structure with wastewater composition and reactor's performance. Self-immobilized granules were developed in simulated wastewater based on different carbon sources (glucose, sugarcane molasses, and milk) in three hybrid anaerobic reactors operated at 37 degrees C. To study archaeal community structure, a polyphasic approach was used with both qualitative and quantitative analysis. While PCR-denaturing gradient gel electrophoresis of 16S rRNA gene did not reveal major shifts in diversity of archaea with change in substrate, quantification of different groups of methanogens and total bacteria by real-time PCR showed variations in relative abundances with the dominance of Methanosaetaceae and Methanobacteriales. These data were supported by differences in the ratio of total counts of archaea and bacteria analyzed by catalyzed reporter deposition - fluorescence in situ hybridization. During hydraulic and organic shocks, the molasses-based reactor showed the best performance followed by the milk- and the glucose-based reactor. The study indicates that carbon source shapes the microbial community structure more in terms of relative abundance with distinct metabolic capacities rather than its diversity itself. (C) 2013 Elsevier B.V. All rights reserved.

In Germany, about 7,200 biogas plants provide heat and electricity for more than 5.3 million households. Despite the knowledge obtained by cultivation and characterization of a number of exemplary species for both biomass degradation and methanogenesis during the past years, cultivation independent approaches point to the presence of several up to now unknown microbial species in biogas plants.

Zinc stannate (Zn2SnO4) nanoparticles with an average size of about 26 nm are synthesized via single-step mechanochemical processing of binary oxide precursors (ZnO and SnO2) at ambient temperature, without the need for the subsequent calcination, thus making the synthesis route very simple and cost-effective. The mechanically induced phase evolution of the 2ZnO + SnO2 mixture is followed by XRD and by a variety of spectroscopic techniques including Sn-119 MAS NMR, Raman spectroscopy, Sn-119 Mossbauer spectroscopy, and XPS. High-resolution TEM studies reveal a non-uniform structure of mechanosynthesized Zn2SnO4 nanoparticles consisting of a crystalline core surrounded by a structurally disordered surface shell. Due to the ability of the applied solid-state spectroscopies to probe the local environment of Sn cations, valuable complementary insight into the nature of the local structural disorder of mechanosynthesized Zn2SnO4 is obtained. The findings hint at a highly nonequilibrium state of the as-prepared stannate characterized by its partly inverse spinel structure and the presence of deformed polyhedra in the surface shell of nanoparticles.

Individuals that reproduce parthenogenetically do not have to produce males and can therefore produce twice as many female offspring. With this twofold reproduction advantage of asexual reproduction, the question of how sex persists in the short term remains unresolved. In the dioecious charophyte Chara canescens , both parthenogenetically reproducing females and sexually reproducing females and males occur sympatrically at only one site in Europe: Neusiedler See-Seewinkel (Austria). By means of four nuclear species-specific microsatellite loci, we examined the interaction between coexisting sexuals and parthenogens by analysing the population structure and gene flow between both reproduction systems. Using a Bayesian assignment method, we found that the sites encompassed two genetically distinct clusters of individuals. The first cluster included genotypes of sexual individuals, which are genetically distinct from a second cluster which included parthenogenetic individuals and few sexually reproducing males, which are genetically identical to the parthenogenetic individuals. However, an analysis of the population genetic structure found no differences with respect to genotypic variation, clonal diversity, and population differentiation between the sympatric parthenogenetically and the sexually reproducing populations. The results indicated that the parthenogenetic individuals cannot outcompete the sexually reproducing individuals.

ABSTRACT Knowledge of the microbial consortia participating in the generation of biogas, especially in methane formation, is still limited. To overcome this limitation, the methanogenic archaeal communities in six full-scale biogas plants supplied with different liquid manures and renewable raw materials as substrates were analyzed by a polyphasic approach. Fluorescence in situ hybridization (FISH) was carried out to quantify the methanogenic Archaea in the reactor samples. In addition, quantitative real-time PCR (Q-PCR) was used to support and complete the FISH analysis. Five of the six biogas reactors were dominated by hydrogenotrophic Methanomicrobiales . The average values were between 60 to 63% of archaeal cell counts (FISH) and 61 to 99% of archaeal 16S rRNA gene copies (Q-PCR). Within this order, Methanoculleus was found to be the predominant genus as determined by amplified rRNA gene restriction analysis. The aceticlastic family Methanosaetaceae was determined to be the dominant methanogenic group in only one biogas reactor, with average values for Q-PCR and FISH between 64% and 72%. Additionally, in three biogas reactors hitherto uncharacterized but potentially methanogenic species were detected. They showed closest accordance with nucleotide sequences of the hitherto unclassified CA-11 (85%) and ARC-I (98%) clusters. These results point to hydrogenotrophic methanogenesis as a predominant pathway for methane synthesis in five of the six analyzed biogas plants. In addition, a correlation between the absence of Methanosaetaceae in the biogas reactors and high concentrations of total ammonia (sum of NH 3 and NH 4 + ) was observed.

The response of the local structure of various types of spinel aluminates, ZnAl2O4 (normal spinel), MgAl2O4 (partly inverse spinel), and Li0.5Al2.5O4 (fully inverse spinel), to mechanical action through high-energy milling is investigated by means of 27Al MAS NMR. Due to the ability of this nuclear spectroscopic technique to probe the local environment of Al nuclei, valuable quantitative insight into the mechanically induced changes in the spinel structure, such as the local cation disorder and the deformation of the polyhedron geometry, is obtained. It is revealed that, independent of the ionic configuration in the initial oxides, the mechanical action tends to randomize cations over the two non-equivalent cation sublattices provided by the spinel structure. The response of the spinels to mechanical treatment is found to be accompanied by the formation of a non-uniform core–shell nanostructure consisting of an ordered crystallite surrounded by a structurally disordered interface/surface shell region. Based on the comparative NMR studies of the non-treated and mechanically treated spinels, an attempt is made to separate the surface effects from the bulk effects in spinel nanoparticles. The non-equilibrium cation distribution and the deformed polyhedra are found to be confined to the near-surface layers of spinel nanoparticles with the thickness extending up to about 0.7 nm. The cation inversion parameter of the mechanically treated spinel is compared with that of the non-treated material at non-ambient conditions.

Transparent nickel gallate spinel films were synthesized by means of an inter-diffusion reaction between NiO ceramics and (001) β-Ga2O3 single crystalline substrates at 1300°C and annealed at various temperatures after removal of NiO pellets. The as-prepared films were characterized by X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy, and optical absorption spectroscopy. It is revealed that the transparent reaction layers are single phase crystalline spinel with preferred orientations. Results from the EDX analysis show a homogeneous composition after equilibration, with a Ga/Ni atomic ratio of about 2.4 and 2.7 for samples quenched from 1300°C and 1400°C, respectively. Optical absorption spectra of spinel films are dominated by ligand field transitions of Ni2+ ions in octahedral sites with overlapping absorption bands of Ni2+ ions on tetrahedral sites.

Quantitative real-time PCR (Q-PCR) is commonly applied for the detection of certain microorganisms in environmental samples. However, some environments, like biomass-degrading biogas fermenters, are enriched with PCR-interfering substances. To study the impact of the DNA extraction protocol on the results of Q-PCR-based analysis of the methane-producing archaeal community in biogas fermenters, nine different protocols with varying cell disruption and DNA purification approaches were tested.Differences in the quantities of the isolated DNA and the purity parameters were found, with the best cell lysis efficiencies being obtained by a combined lysozyme/SDS-based lysis. When DNA was purified by sephacryl columns, the amount of DNA decreased by one log cycle but PCR inhibitors were eliminated sufficiently.In the case of detection of methanogenic Archaea, the chosen DNA isolation protocol strongly influenced the Q-PCR-based determination of 165 rDNA copy numbers. For example, with protocols including mechanical cell disruption, the 16S rDNA of Methanobacteriales were predominantly amplified (81-90% of the total 16S rDNA copy numbers), followed by the 165 rDNA of Methanomicrobiales (9-18%). In contrast, when a lysozyme/SDS-based cell lysis was applied, the 16S rDNA copy numbers determined for these two orders were the opposite (Methanomicrobiales 82-95%, Methanobacteriales 4-18%). In extreme cases, the DNA isolation method led to discrimination of some groups of methanogens (e.g. members of the Methanosaetaceae).In conclusion, for extraction of high amounts of microbial DNA with high purity from samples of biogas plants, a combined lysozyme/SDS-based cell lysis followed by a purification step with sephacryl columns is recommended. (C) 2010 Elsevier GmbH. All rights reserved.

Energy production of renewable raw material is of increasing importance for sustainable energy production. As an indispensable prerequirement for further upgrading of technical equipment and operation modes of biogas plants, a deeper knowledge of the microbial community responsible for methane formation is crucial. To overcome these limitations a mesophilic biogas plant converting pig manure, maize silage, and grains of crop was sampled and subsequently analysed by construction of a methanogenic Archaea specific 16S rRNA gene clone library combined with PCR-RFLP analysis and group-specific quantitative real-time PCR (qPCR). Seventy percent of all analysed clones belonged to the order Methanomicrobiales, whereas 13% belonged to Methanosarcinales, 6% belonged to the Methanobacteriales group, and 11% of all detected clones were assigned to the CA11 and Arch1 cluster. Comparable percentages were obtained with qPCR: 84% of all detected 16S rRNA gene copy numbers were affiliated with the Methanomicrobiales, while only 14% belonged to the Methanosarcinales and 2% to the Methanobacteriales order. In conclusion, both approaches detected similar archaeal groups and revealed nearly the same abundance, pointing to a predominance of hydrogenotrophic methanogens in the biogas plant.

A low-rank Slovak sub-bituminous coal from the Handlová deposit was physically treated by washing in a water-only cyclone with the goal to find the separation effect for inorganic (mainly Fe-bearing minerals) and organic substances (humic acids, diterpanes). A high-quality coal product with the ash content in the dry matter of 9.02% and carbon content of Cd=68.12% at a mass yield of 29.51% was obtained using the water-only cyclone processing. At first, the physically treated coal samples were detailed characterized by XRD, 57Fe Mössbauer spectroscopy, FT-IR and HR-TEM. In addition to non-crystalline organic coal components, inorganic compounds belonging to silicate minerals (kaolinite, muscovite and quartz) as well as to Fe-bearing sulphide minerals (pyrite) were identified in the sub-bituminous coal by XRD. 57Fe Mössbauer spectroscopy detected the presence of iron carbonate (siderite), iron-containing clay mineral and two sulphur-containing minerals (pyrite, jarosite) in the untreated coal. On the other hand, only one Fe-bearing mineral, (pyrite) was found in the washed coal. Effect of the physical separation is also demonstrated in FT-IR spectra, where the peak at 1040cm−1 representing the silicate component in the untreated sample is not detectable in the washed coal sample. Presence of extractive organic substances, i.e. humic acids and tetracyclic diterpane (16α(H)-phyllocladane), in the hydrocyclone products is also evidenced. It was confirmed that the isolated diterpenoic compound is attendant in the washed product with the lowest ash content and it is assimilated with the organic part of coal. Surprisingly, humic acids were found in the highest concentration in the slurry that has the highest content of ash (63.14%).