scholarly journals Archaeal Population Dynamics during Sequential Reduction Processes in Rice Field Soil

2000 ◽  
Vol 66 (7) ◽  
pp. 2732-2742 ◽  
Author(s):  
Tillmann Lueders ◽  
Michael Friedrich
Keyword(s):  
Population Dynamics ◽  
Gene Frequency ◽  
Rice Field ◽  
Rflp Analysis ◽  
Ssu Rrna ◽  
Field Soil ◽  
Reduction Processes ◽  
Rice Field Soil ◽  
Restriction Sites ◽  
Over Time

ABSTRACT The population dynamics of Archaea after flooding of an Italian rice field soil were studied over 17 days. Anoxically incubated rice field soil slurries exhibited a typical sequence of reduction processes characterized by reduction of nitrate, Fe3+, and sulfate prior to the initiation of methane production. Archaeal population dynamics were followed using a dual approach involving molecular sequence retrieval and fingerprinting of small-subunit (SSU) rRNA genes. We retrieved archaeal sequences from four clone libraries (30 each) constructed for different time points (days 0, 1, 8, and 17) after flooding of the soil. The clones could be assigned to known methanogens (i.e., Methanosarcinaceae,Methanosaetaceae, Methanomicrobiaceae, andMethanobacteriaceae) and to novel euryarchaeotal (rice clusters I, II, and III) and crenarchaeotal (rice clusters IV and VI) lineages previously detected in anoxic rice field soil and on rice roots (R. Grosskopf, S. Stubner, and W. Liesack, Appl. Environ. Microbiol. 64:4983–4989, 1998). During the initiation of methanogenesis (days 0 to 17), we detected significant changes in the frequency of individual clones, especially of those affiliated with theMethanosaetaceae and Methanobacteriaceae. However, these findings could not be confirmed by terminal restriction fragment length polymorphism (T-RFLP) analysis of SSU rDNA amplicons. Most likely, the fluctuations in sequence composition of clone libraries resulted from cloning bias. Clonal SSU rRNA gene sequences were used to define operational taxonomic units (OTUs) for T-RFLP analysis, which were distinguished by group-specific TaqI restriction sites. Sequence analysis showed a high degree of conservation of TaqI restriction sites within the different archaeal lineages present in Italian rice field soil. Direct T-RFLP analysis of archaeal populations in rice field soil slurries revealed the presence of all archaeal lineages detected by cloning with a predominance of terminal restriction fragments characteristic of rice cluster I (389 bp), Methanosaetaceae (280 bp), andMethanosarcinaceae/rice cluster VI (182 bp). In general, the relative gene frequency of most detected OTUs remained rather constant over time during the first 17 days after flooding of the soil. Most minor OTUs (e.g., Methanomicrobiaceae and rice cluster III) and Methanosaetaceae did not change in relative frequency. Rice cluster I (37 to 30%) and to a lesser extent rice cluster IV as well as Methanobacteriaceae decreased over time. Only the relative abundance of Methanosarcinaceae(182 bp) increased, roughly doubling from 15 to 29% of total archaeal gene frequency within the first 11 days, which was positively correlated to the dynamics of acetate and formate concentrations. Our results indicate that a functionally dynamic ecosystem, a rice field soil after flooding, was linked to a relatively stable archaeal community structure.

scholarly journals Effect of Temperature on Carbon and Electron Flow and on the Archaeal Community in Methanogenic Rice Field Soil

2000 ◽  
Vol 66 (11) ◽  
pp. 4790-4797 ◽  
Author(s):  
Axel Fey ◽  
Ralf Conrad
Keyword(s):  
Steady State ◽  
Rice Field ◽  
Electron Flow ◽  
Rflp Analysis ◽  
Archaeal Community ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Field Soil ◽  
Rice Field Soil ◽  
Different Temperatures

ABSTRACT Temperature is an important factor controlling CH4production in anoxic rice soils. Soil slurries, prepared from Italian rice field soil, were incubated anaerobically in the dark at six temperatures of between 10 to 37°C or in a temperature gradient block covering the same temperature range at intervals of 1°C. Methane production reached quasi-steady state after 60 to 90 days. Steady-state CH4 production rates increased with temperature, with an apparent activation energy of 61 kJ mol−1. Steady-state partial pressures of the methanogenic precursor H2 also increased with increasing temperature from <0.5 to 3.5 Pa, so that the Gibbs free energy change of H2 plus CO2-dependent methanogenesis was kept at −20 to −25 kJ mol of CH4 −1 over the whole temperature range. Steady-state concentrations of the methanogenic precursor acetate, on the other hand, increased with decreasing temperature from <5 to 50 μM. Simultaneously, the relative contribution of H2 as methanogenic precursor decreased, as determined by the conversion of radioactive bicarbonate to 14CH4, so that the carbon and electron flow to CH4 was increasingly dominated by acetate, indicating that psychrotolerant homoacetogenesis was important. The relative composition of the archaeal community was determined by terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA genes (16S rDNA). T-RFLP analysis differentiated the archaeal Methanobacteriaceae,Methanomicrobiaceae, Methanosaetaceae,Methanosarcinaceae, and Rice clusters I, III, IV, V, and VI, which were all present in the rice field soil incubated at different temperatures. The 16S rRNA genes of Rice cluster I andMethanosaetaceae were the most frequent methanogenic groups. The relative abundance of Rice cluster I decreased with temperature. The substrates used by this microbial cluster, and thus its function in the microbial community, are unknown. The relative abundance of acetoclastic methanogens, on the other hand, was consistent with their physiology and the acetate concentrations observed at the different temperatures, i.e., the high-acetate-requiring Methanosarcinaceae decreased and the more modest Methanosaetaceae increased with increasing temperature. Our results demonstrate that temperature not only affected the activity but also changed the structure and the function (carbon and electron flow) of a complex methanogenic system.

scholarly journals Effects of Amendment with Ferrihydrite and Gypsum on the Structure and Activity of Methanogenic Populations in Rice Field Soil

2002 ◽  
Vol 68 (5) ◽  
pp. 2484-2494 ◽  
Author(s):  
Tillmann Lueders ◽  
Michael W. Friedrich
Keyword(s):  
Rice Field ◽  
Small Subunit ◽  
Strong Increase ◽  
Polymorphism Analysis ◽  
Ssu Rrna ◽  
The Novel ◽  
Field Soil ◽  
Sulfate Reducing ◽  
Rice Field Soil ◽  
Reducing Bacteria

ABSTRACT Methane emission from paddy fields may be reduced by the addition of electron acceptors to stimulate microbial populations competitive to methanogens. We have studied the effects of ferrihydrite and gypsum (CaSO4 · 2H2O) amendment on methanogenesis and population dynamics of methanogens after flooding of Italian rice field soil slurries. Changes in methanogen community structure were followed by archaeal small subunit (SSU) ribosomal DNA (rDNA)- and rRNA-based terminal restriction fragment length polymorphism analysis and by quantitative SSU rRNA hybridization probing. Under ferrihydrite amendment, acetate was consumed efficiently (<60 μM) and a rapid but incomplete inhibition of methanogenesis occurred after 3 days. In contrast to unamended controls, the dynamics of Methanosarcina populations were largely suppressed as indicated by rDNA and rRNA analysis. However, the low acetate availability was still sufficient for activation of Methanosaeta spp., as indicated by a strong increase of SSU rRNA but not of relative rDNA frequencies. Unexpectedly, rRNA amounts of the novel rice cluster I (RC-I) methanogens increased significantly, while methanogenesis was low, which may be indicative of transient energy conservation coupled to Fe(III) reduction by these methanogens. Under gypsum addition, hydrogen was rapidly consumed to low levels (∼0.4 Pa), indicating the presence of a competitive population of hydrogenotrophic sulfate-reducing bacteria (SRB). This was paralleled by a suppressed activity of the hydrogenotrophic RC-I methanogens as indicated by the lowest SSU rRNA quantities detected in all experiments. Full inhibition of methanogenesis only became apparent when acetate was depleted to nonpermissive thresholds (<5 μM) after 10 days. Apparently, a competitive, acetotrophic population of SRB was not present initially, and hence, acetotrophic methanosarcinal populations were less suppressed than under ferrihydrite amendment. In conclusion, although methane production was inhibited effectively under both mitigation regimens, different methanogenic populations were either suppressed or stimulated, which demonstrates that functionally similar disturbances of an ecosystem may result in distinct responses of the populations involved.

scholarly journals Response of the protistan community of a rice field soil to different oxygen tensions

2017 ◽  
Vol 93 (5) ◽  
Author(s):  
Yuriko Takenouchi ◽  
Kazufumi Iwasaki ◽  
Jun Murase
Keyword(s):  
Rice Field ◽  
Field Soil ◽  
Rice Field Soil ◽  
Oxygen Tensions

scholarly journals Streptacidiphilus oryzae sp. nov., an actinomycete isolated from rice-field soil in Thailand

2006 ◽  
Vol 56 (6) ◽  
pp. 1257-1261 ◽  
Author(s):  
Liming Wang ◽  
Ying Huang ◽  
Zhiheng Liu ◽  
Michael Goodfellow ◽  
Carlos Rodríguez
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Phylogenetic Trees ◽  
Rice Field ◽  
Gene Tree ◽  
Morphological Properties ◽  
Rrna Gene ◽  
New Taxon ◽  
Field Soil ◽  
Rice Field Soil

The taxonomic position of ten acidophilic actinomycetes isolated from an acidic rice-field soil was established using a polyphasic approach. 16S rRNA gene sequences determined for the isolates were aligned with corresponding sequences of representatives of the genera Kitasatospora, Streptacidiphilus and Streptomyces and phylogenetic trees were inferred using four tree-making algorithms. The isolates had identical sequences and formed a distinct branch at the periphery of the Streptacidiphilus 16S rRNA gene tree. The chemotaxonomic and morphological properties of representative isolates were consistent with their assignment to the genus Streptacidiphilus. The isolates shared nearly identical phenotypic profiles that readily distinguished them from representatives of the established species of Streptacidiphilus. It is evident from the genotypic and phenotypic data that the isolates form a homogeneous group that corresponds to a novel species in the genus Streptacidiphilus. The name proposed for this new taxon is Streptacidiphilus oryzae sp. nov.; the type strain is strain TH49T (=CGMCC 4.2012T=JCM 13271T).

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