The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Seokhwan Hwang - One of the best experts on this subject based on the ideXlab platform.
-
Behavior of methanogens during start-up of farm-scale anaerobic digester treating swine wastewater
Process Biochemistry, 2013Co-Authors: Kyungjin Cho, Woong Kim, Joonyeob Lee, Seokhwan HwangAbstract:Abstract The aim of this study was to monitor the changes in methanogenic community structures in an anaerobic digester (250 m3 working volume) during start-up including prolonged starvation periods. Redundancy analysis was performed to investigate the correlations between environmental variables and microbial community structures. The anaerobic digester was operated for 591 days at alternating operating temperatures. In initial start-up period at stage I (35 °C), growth of various species of mesophilic aceticlastic methanogens (AMs) and hydrogenotrophic methanogens (HMs) was observed. Methanobacteriales species survived better than other methanogens under long-term starvation conditions. In stage II (50 °C), HMs became dominant over AMs as the operating temperature changed from mesophilic to thermophilic due to increase of ammonia inhibition. In stage III (35 °C), only the Methanomicrobiales population significantly increased during 50 days of HRT while Methanobacteriales dominated over 15 days of HRT. The influent pH negatively correlated with all methanogenic populations especially in stage II.
-
Variations in methanogenic population structure under overloading of pre-acidified high-strength organic wastewaters
Process Biochemistry, 2011Co-Authors: Seung Gu Shin, Woong Kim, Bi Wen Zhou, Seungyong Lee, Seokhwan HwangAbstract:Methanogenic populations were quantitatively investigated in two separate anaerobic reactors, which received effluents from acidogenesis of either food waste-recycling wastewater or swine wastewater. Each set of the anaerobic digesters was operated under high organic loading rate (OLR) conditions (8.3–39.8 g chemical oxygen demand (COD)/L/d) with four different hydraulic retention times (10.4–3.0 days). Real-time PCR analysis demonstrated that the order Methanosarcinales was the most abundant (>55%) methanogenic group in the six runs with >50% COD removal, while the dominance (>70%) of Methanobacteriales was observed in the other two runs (
-
Use of order-specific primers to investigate the methanogenic diversity in acetate enrichment system
Journal of Industrial Microbiology & Biotechnology, 2008Co-Authors: Seung Gu Shin, Kwanghyun Hwang, Seokhwan HwangAbstract:The applicability of order-specific primers in minimizing the possible underestimation of microbial diversity was evaluated via denaturing gradient gel electrophoresis (DGGE) analysis of a lab-scale anaerobic digester. Initially, a population analysis with real-time quantitative PCR demonstrated the existence of three methanogenic orders— Methanobacteriales , Methanomicrobiales , and Methanosarcinales —throughout the reaction period. DGGE analyses with three pairs of order-specific primers yielded eight operational taxonomic units (OTUs), whereas DGGE analysis with two independent Archaea-specific primers identified only five. Moreover, the order-specific primers amplified at least one OTU affiliated with each order, whereas no members of Methanobacteriales or Methanomicrobiales were identified with Archaea-specific primers in most samples. These findings provide evidence that order-specific analysis can detect the diversity of methanogens in greater detail than conventional Archaea-specific analysis.
Shir-ly Huang - One of the best experts on this subject based on the ideXlab platform.
-
Multiple approaches to characterize the microbial community in a thermophilic anaerobic digester running on swine manure: a case study.
Microbiological research, 2014Co-Authors: Nguyen Ngoc Tuan, Yi-chia Chang, Shir-ly HuangAbstract:In this study, the first survey of microbial community in thermophilic anaerobic digester using swine manure as sole feedstock was performed by multiple approaches including denaturing gradient gel electrophoresis (DGGE), clone library and pyrosequencing techniques. The integrated analysis of 21 DGGE bands, 126 clones and 8506 pyrosequencing read sequences revealed that Clostridia from the phylum Firmicutes account for the most dominant Bacteria. In addition, our analysis also identified additional taxa that were missed by the previous researches, including members of the bacterial phyla Synergistetes, Planctomycetes, Armatimonadetes, Chloroflexi and Nitrospira which might also play a role in thermophilic anaerobic digester. Most archaeal 16S rRNA sequences could be assigned to the order Methanobacteriales instead of Methanomicrobiales comparing to previous studies. In addition, this study reported that the member of Methanothermobacter genus was firstly found in thermophilic anaerobic digester.
Ralf Conrad - One of the best experts on this subject based on the ideXlab platform.
-
temperature effects on structure and function of the methanogenic microbial communities in two paddy soils and one desert soil
Soil Biology & Biochemistry, 2018Co-Authors: Melanie Klose, Ralf ConradAbstract:Abstract Temperature is an important factor regulating the production of the greenhouse gas CH4. Previous studies of temperate methanogenic paddy soils from Italy showed that structure and function of the soil microbial communities changed drastically when temperature was increased to values higher than about 40 °C. Since methanogenic archaea are ubiquitous in both wetland and upland soils, we wondered whether other soils would behave similarly. Therefore, we compared paddy soils from Italy and the Philippines, which have different microbial community structures, and also investigated a desert soil from Utah (USA), which expressed CH4 production upon flooding. We incubated these soils under anoxic conditions at three different temperatures. We determined composition, abundance and function of the methanogenic archaeal and bacterial communities using illumina HiSeq sequencing, qPCR and analysis of activity and stable isotope fractionation, respectively. At moderate temperatures (25 °C and 35 °C), CH4 was always produced by a combination of acetoclastic and hydrogenotrophic methanogenesis. However, at elevated temperature (45 °C) the combination of acetoclastic and hydrogenotrophic methanogenesis was only maintained in the Philippines soil, which contained hydrogenotrophic (Methanobacteriales, Methanocellales, Methanosarcinaceae) and acetoclastic (Methanosarcinaceae, Methanotrichaceae) methanogenic taxa under these conditions. In Italian and Utah soil by contrast, CH4 production at 45 °C occurred by hydrogenotrophic methanogenesis, and the archaeal community was lacking acetoclastic methanogens. Acetate was instead oxidized by Thermoanaerobacteraceae (and perhaps Heliobacteriaceae) affiliated species which were syntrophically connected to hydrogenotrophic Methanocellales and Methanobacteriales. Our results showed that the different soils exhibited different structures and functions of the methanogenic archaeal and bacterial communities at elevated versus moderate temperatures. While acetoclastic methanogens in the Philippines paddy soil were able to tolerate elevated temperatures, those in Italian paddy soil and Utah desert soil were not. Instead, syntrophic acetate oxidation allowed the complete degradation of organic matter to CH4 and CO2.
-
Methanogenic Pathway and Archaeal Communities in Three Different Anoxic Soils Amended with Rice Straw and Maize Straw
Frontiers in microbiology, 2012Co-Authors: Ralf Conrad, Melanie Klose, Amnat ChidthaisongAbstract:Addition of straw is common practice in rice agriculture, but its effect on the path of microbial CH4 production and the microbial community involved is not well known. Since straw from rice (C3 plant) and maize plants (C4 plant) exhibit different δ13C values, we compared the effect of these straw types using anoxic rice field soils from Italy and China, and also a soil from Thailand that had previously not been flooded. The temporal patterns of production of CH4 and its major substrates H2 and acetate, were slightly different between rice straw and maize straw. Addition of methyl fluoride, an inhibitor of aceticlastic methanogenesis, resulted in partial inhibition of acetate consumption and CH4 production. The δ13C of the accumulated CH4 and acetate reflected the different δ13C values of rice straw versus maize straw. However, the relative contribution of hydrogenotrophic methanogenesis to total CH4 production exhibited a similar temporal change when scaled to CH4 production irrespectively of whether rice straw or maize straw was applied. The composition of the methanogenic archaeal communities was characterized by terminal restriction fragment length polymorphism (T-RFLP) analysis and was quantified by quantitative PCR (qPCR) targeting archaeal 16S rRNA genes or methanogenic mcrA genes.. The size of the methanogenic communities generally increased during incubation with straw, but the straw type had little effect. Instead, differences were found between the soils, with Methanosarcinaceae and Methanobacteriales dominating straw decomposition in Italian soil, Methanosarcinaceae, Methanocellales, and Methanobacteriale in China soil, and Methanosarcinaceae and Methanocellales in Thailand soil. The experiments showed that methanogenic degradation in different soils involved different methanogenic population dynamics. However, the path of CH4 production was hardly different between degradation of rice straw versus maize straw and was also similar for the different soil
-
Dynamics of the methanogenic archaeal community in anoxic rice soil upon addition of straw
European Journal of Soil Science, 2006Co-Authors: Ralf Conrad, Melanie KloseAbstract:Summary Addition of rice straw, which is a common practice in rice agriculture, generally results in enhanced production and emission of the greenhouse gas methane (CH4). However, it is unclear whether straw addition affects only the activity or also the composition of the methanogenic microbial community. It is also unclear to what extent methanogenic archaea would be able to proliferate in the soil. Anoxic slurries of Italian rice-field soil produced CH4 after a lag, during which ferric iron and sulfate were reduced. Addition of rice straw slightly decreased this lag and greatly enhanced the subsequent production of CH4. At the same time, addition of rice straw enhanced the intermediate production of H2 and acetate that served as the methanogenic substrates. Compared with the unamended control, the addition of rice straw resulted in an increased concentration of phospholipid fatty acids in the soil. Quantitative ‘real-time’ PCR targeting the 16S rRNA gene also showed increased copy numbers of both Bacteria and Archaea in the straw-amended soil at the end of the experiment. The composition of the archaeal community was followed over time by terminal restriction length polymorphism (T-RFLP) analysis of the archaeal 16S rRNA genes extracted from straw-amended soil and the control. Rice Cluster-I (RC-I) methanogens and Methanosarcinaceae were the most abundant methanogenic populations, followed by Methanobacteriales, Methanomicrobiales and Methanosaetaceae. Addition of rice straw resulted in a relative increase of Methanosarcinaceae and Methanobacteriales and a relative decrease of RC-I methanogens and Methanomicrobiales. Our results revealed a dynamic methanogenic community in anoxic rice-field soil and showed that addition of organic matter selectively enhanced the growth of particular methanogenic populations, which were apparently better adapted to the presence of straw than the others. The extent of archaeal growth was consistent with that expected theoretically from the ambient Gibbs free energies of hydrogenotrophic and acetoclastic methanogenesis.
Melanie Klose - One of the best experts on this subject based on the ideXlab platform.
-
temperature effects on structure and function of the methanogenic microbial communities in two paddy soils and one desert soil
Soil Biology & Biochemistry, 2018Co-Authors: Melanie Klose, Ralf ConradAbstract:Abstract Temperature is an important factor regulating the production of the greenhouse gas CH4. Previous studies of temperate methanogenic paddy soils from Italy showed that structure and function of the soil microbial communities changed drastically when temperature was increased to values higher than about 40 °C. Since methanogenic archaea are ubiquitous in both wetland and upland soils, we wondered whether other soils would behave similarly. Therefore, we compared paddy soils from Italy and the Philippines, which have different microbial community structures, and also investigated a desert soil from Utah (USA), which expressed CH4 production upon flooding. We incubated these soils under anoxic conditions at three different temperatures. We determined composition, abundance and function of the methanogenic archaeal and bacterial communities using illumina HiSeq sequencing, qPCR and analysis of activity and stable isotope fractionation, respectively. At moderate temperatures (25 °C and 35 °C), CH4 was always produced by a combination of acetoclastic and hydrogenotrophic methanogenesis. However, at elevated temperature (45 °C) the combination of acetoclastic and hydrogenotrophic methanogenesis was only maintained in the Philippines soil, which contained hydrogenotrophic (Methanobacteriales, Methanocellales, Methanosarcinaceae) and acetoclastic (Methanosarcinaceae, Methanotrichaceae) methanogenic taxa under these conditions. In Italian and Utah soil by contrast, CH4 production at 45 °C occurred by hydrogenotrophic methanogenesis, and the archaeal community was lacking acetoclastic methanogens. Acetate was instead oxidized by Thermoanaerobacteraceae (and perhaps Heliobacteriaceae) affiliated species which were syntrophically connected to hydrogenotrophic Methanocellales and Methanobacteriales. Our results showed that the different soils exhibited different structures and functions of the methanogenic archaeal and bacterial communities at elevated versus moderate temperatures. While acetoclastic methanogens in the Philippines paddy soil were able to tolerate elevated temperatures, those in Italian paddy soil and Utah desert soil were not. Instead, syntrophic acetate oxidation allowed the complete degradation of organic matter to CH4 and CO2.
-
Methanogenic Pathway and Archaeal Communities in Three Different Anoxic Soils Amended with Rice Straw and Maize Straw
Frontiers in microbiology, 2012Co-Authors: Ralf Conrad, Melanie Klose, Amnat ChidthaisongAbstract:Addition of straw is common practice in rice agriculture, but its effect on the path of microbial CH4 production and the microbial community involved is not well known. Since straw from rice (C3 plant) and maize plants (C4 plant) exhibit different δ13C values, we compared the effect of these straw types using anoxic rice field soils from Italy and China, and also a soil from Thailand that had previously not been flooded. The temporal patterns of production of CH4 and its major substrates H2 and acetate, were slightly different between rice straw and maize straw. Addition of methyl fluoride, an inhibitor of aceticlastic methanogenesis, resulted in partial inhibition of acetate consumption and CH4 production. The δ13C of the accumulated CH4 and acetate reflected the different δ13C values of rice straw versus maize straw. However, the relative contribution of hydrogenotrophic methanogenesis to total CH4 production exhibited a similar temporal change when scaled to CH4 production irrespectively of whether rice straw or maize straw was applied. The composition of the methanogenic archaeal communities was characterized by terminal restriction fragment length polymorphism (T-RFLP) analysis and was quantified by quantitative PCR (qPCR) targeting archaeal 16S rRNA genes or methanogenic mcrA genes.. The size of the methanogenic communities generally increased during incubation with straw, but the straw type had little effect. Instead, differences were found between the soils, with Methanosarcinaceae and Methanobacteriales dominating straw decomposition in Italian soil, Methanosarcinaceae, Methanocellales, and Methanobacteriale in China soil, and Methanosarcinaceae and Methanocellales in Thailand soil. The experiments showed that methanogenic degradation in different soils involved different methanogenic population dynamics. However, the path of CH4 production was hardly different between degradation of rice straw versus maize straw and was also similar for the different soil
-
Dynamics of the methanogenic archaeal community in anoxic rice soil upon addition of straw
European Journal of Soil Science, 2006Co-Authors: Ralf Conrad, Melanie KloseAbstract:Summary Addition of rice straw, which is a common practice in rice agriculture, generally results in enhanced production and emission of the greenhouse gas methane (CH4). However, it is unclear whether straw addition affects only the activity or also the composition of the methanogenic microbial community. It is also unclear to what extent methanogenic archaea would be able to proliferate in the soil. Anoxic slurries of Italian rice-field soil produced CH4 after a lag, during which ferric iron and sulfate were reduced. Addition of rice straw slightly decreased this lag and greatly enhanced the subsequent production of CH4. At the same time, addition of rice straw enhanced the intermediate production of H2 and acetate that served as the methanogenic substrates. Compared with the unamended control, the addition of rice straw resulted in an increased concentration of phospholipid fatty acids in the soil. Quantitative ‘real-time’ PCR targeting the 16S rRNA gene also showed increased copy numbers of both Bacteria and Archaea in the straw-amended soil at the end of the experiment. The composition of the archaeal community was followed over time by terminal restriction length polymorphism (T-RFLP) analysis of the archaeal 16S rRNA genes extracted from straw-amended soil and the control. Rice Cluster-I (RC-I) methanogens and Methanosarcinaceae were the most abundant methanogenic populations, followed by Methanobacteriales, Methanomicrobiales and Methanosaetaceae. Addition of rice straw resulted in a relative increase of Methanosarcinaceae and Methanobacteriales and a relative decrease of RC-I methanogens and Methanomicrobiales. Our results revealed a dynamic methanogenic community in anoxic rice-field soil and showed that addition of organic matter selectively enhanced the growth of particular methanogenic populations, which were apparently better adapted to the presence of straw than the others. The extent of archaeal growth was consistent with that expected theoretically from the ambient Gibbs free energies of hydrogenotrophic and acetoclastic methanogenesis.
Paul Illmer - One of the best experts on this subject based on the ideXlab platform.
-
Abundance and potential metabolic activity of methanogens in well-aerated forest and grassland soils of an alpine region.
FEMS Microbiology Ecology, 2015Co-Authors: Katrin Hofmann, Nadine Praeg, Mira Mutschlechner, Andreas Wagner, Paul IllmerAbstract:Although methanogens were recently discovered to occur in aerated soils, alpine regions have not been extensively studied for their presence so far. Here, the abundance of archaea and the methanogenic guilds Methanosarcinales , Methanococcales , Methanobacteriales , Methanomicrobiales , and Methanocella spp. was studied at 16 coniferous forest and 14 grassland sites located at the montane and subalpine belts of the Northern Limestone Alps (calcareous) and the Austrian Central Alps (siliceous) using quantitative real-time PCR. Abundance of archaea, methanogens and the methanogenic potentials were significantly higher in grasslands than in forests. Furthermore, methanogenic potentials of calcareous soils were higher due to pH. Methanococcales , Methanomicrobiales , and Methanocella spp. were detected in all collected samples, which indicates that they are autochthonous, while Methanobacteriales were absent from four out of 16 forest soils. Methanosarcinales were absent from ten out of 16 forest soils and two out of 14 grassland soils. Nevertheless, together with Methanococcales they represented the majority of the 16S rRNA gene copies quantified from the grassland soils. Contrarily, forest soils were clearly dominated by Methanococcales . Our results indicate a higher diversity of methanogens in well-aerated soils than previously believed and that pH mainly influences their abundances and activities.
-
Methanosarcina spp., the key to relieve the start-up of a thermophilic anaerobic digestion suffering from high acetic acid loads.
Bioresource Technology, 2013Co-Authors: Philipp Lins, Christoph Reitschuler, Paul IllmerAbstract:Abstract This paper investigates if it is possible to produce inocula to counteract high acetic acid (CH3COO−) concentrations during thermophilic anaerobic digestion. To this end, fermenter sludge was exposed for different durations to either gradually increasing CH3COO− concentrations or directly exposed to a high concentration (150 mM). Altogether, these enrichments led to inocula with a distinct decrease of representatives of Methanobacteriales, while those of Methanoculleus spp. were hardly affected by any treatment. After the inoculation, good agreements of the abundance of Methanosarcinales and Methanoculleus spp. with total DNA content and methane production rate were apparent. In addition, a gradual adaptation of the inoculum for at least 4 weeks led to a significant increase of Methanosarcina spp. during the subsequent fermentation. These results demonstrate the potential of bioaugmentation to relieve the start-up of an anaerobic digestion suffering from high CH3COO− loads, especially pointing to the robust acetoclastic genus Methanosarcina.
-
Primer evaluation and adaption for cost-efficient SYBR Green-based qPCR and its applicability for specific quantification of methanogens
World Journal of Microbiology & Biotechnology, 2013Co-Authors: Christoph Reitschuler, Philipp Lins, Paul IllmerAbstract:In the present study nine promising primer sets, targeting Archaea and methanogenic Archaea in particular, were evaluated in silico, in vitro and in situ concerning specificity, accuracy and applicability in end-point (ep-) and especially quantitative (q-)PCR research. The main goal was to adapt and evaluate already adapted primer sets, which were partially designed in combination with TaqMan probes, in substantially cheaper SYBR Green-based qPCR applications. An initial 16S rRNA gene bank-based in silico evaluation revealed high coverage potentials for all primers within targeted groups, ranging from 71 to 90 %, except the Methanosaeta specific set showing a low potential of 37 %. Mentionable cross-reacting potentials could be detected for the Methanothermobacter, Methanomicrobiales and Methanoculleus sets. The in vitro evaluation with selected reference organisms revealed a specific behavior for most primer sets, while the Methanosarcina and Methanothermobacter sets showed most problematic cross-reactions in epPCR application. We were able to show that primers for detecting the total archaeal community, methanogenic orders Methanosarcinales, Methanobacteriales, Methanococcales and the genus Methanoculleus performed in a highly specific way and allowed an accurate quantification of targeted organisms without the use of expensive TaqMan probes. However, primer pairs designed for detecting Methanomicrobiales, Methanothermobacter, Methanosarcina and Methanosaeta are not suitable for SYBR Green applications. The reliability of in situ quantifications was assessed for a typical methanogenic community, derived from a thermophilic fermenter, and confirmed via denaturing gradient gel band quantification and sequencing. Thereby, we revealed high abundances of methanogenic Archaea, mainly comprising Methanoculleus and Methanosarcinales, while Methanobacteriales only formed a minor fraction.