scholarly journals Active viral population dynamics in frozen Arctic peat soil revealed with H218O stable isotope probing metagenomics

2021 ◽  
Author(s):  
Gareth Trubl ◽  
Jeffrey A. Kimbrel ◽  
Jose Liquet-Gonzalez ◽  
Erin E. Nuccio ◽  
Peter K. Weber ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Peat Soil ◽  
Stable Isotope Probing ◽  
Viral Population ◽  
Soil Processes ◽  
Carbohydrate Utilization ◽  
Bacterial Populations ◽  
Viral Ecology ◽  
Bacterial Phyla ◽  
Winter Conditions

AbstractWinter soil processes are critical to the carbon balance of northern ecosystems, yet the microbial ecology governing biogeochemical cycling in frozen soils is largely unknown. We used stable isotope probing targeted metagenomics to reveal the genomic potential of active microbial populations, with an emphasis on viruses, in soils. Peat soils were incubated under simulated winter conditions (subzero and anoxic) with H218O or natural abundance water for 184 and 370 days. Isotope incorporation revealed 46 active bacterial populations (MAGs; spanning 9 bacterial phyla) and 243 active viral populations (vOTUs). Active hosts were predicted for 33% of the active vOTUs and were some of the most abundant MAGs, having capacity for fermentation and carbohydrate utilization. Additionally, almost one-third of vOTUs carried auxiliary metabolic genes spanning five functional categories, highlighting the potential impact of viruses in microbial biogeochemistry. CO2 production throughout the incubation supports our evidence of microbial activities under winter conditions. Our results revealed a multi-trophic and changing microbial community in tandem with a changing viral community targeting dominant active bacteria consistent with the “kill-the-winner” hypothesis. These data have important implications for low-temperature soil processes in northern peatlands and reveal active host-linked soil viral ecology, with potential multifaceted biogeochemical impacts.

scholarly journals Acetate Repression of Methane Oxidation by Supplemental Methylocella silvestris in a Peat Soil Microcosm

2011 ◽  
Vol 77 (12) ◽  
pp. 4234-4236 ◽  
Author(s):  
M. Tanvir Rahman ◽  
Andrew Crombie ◽  
Hélène Moussard ◽  
Yin Chen ◽  
J. Colin Murrell
Keyword(s):  
Stable Isotope ◽  
Methane Oxidation ◽  
Environmental Samples ◽  
Peat Soil ◽  
Methane Monooxygenase ◽  
Laboratory Culture ◽  
Stable Isotope Probing ◽  
Soil Microcosm ◽  
Content Type

ABSTRACTMethylocellaspp. are facultative methanotrophs that grow on methane and multicarbon substrates, such as acetate. Acetate represses transcription of methane monooxygenase ofMethylocella silvestrisin laboratory culture. DNA stable-isotope probing (DNA-SIP) using13C-methane and12C-acetate, carried out withMethylocella-spiked peat soil, showed that acetate also repressed methane oxidation byMethylocellain environmental samples.

scholarly journals Nutrient Amendments in Soil DNA Stable Isotope Probing Experiments Reduce the Observed Methanotroph Diversity

2006 ◽  
Vol 73 (3) ◽  
pp. 798-807 ◽  
Author(s):  
Aur�lie C�bron ◽  
Levente Bodrossy ◽  
Nancy Stralis-Pavese ◽  
Andrew C. Singer ◽  
Ian P. Thompson ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Stable Isotope Probing ◽  
Population Diversity ◽  
Type I ◽  
Mineral Salts ◽  
Bacterial Populations ◽  
Soil Dna ◽  
Gradient Gel Electrophoresis ◽  
Soil Water Conditions

ABSTRACT Stable isotope probing (SIP) can be used to analyze the active bacterial populations involved in a process by incorporating 13C-labeled substrate into cellular components such as DNA. Relatively long incubation times are often used with laboratory microcosms in order to incorporate sufficient 13C into the DNA of the target organisms. Addition of nutrients can be used to accelerate the processes. However, unnatural concentrations of nutrients may artificially change bacterial diversity and activity. In this study, methanotroph activity and diversity in soil was examined during the consumption of 13CH4 with three DNA-SIP experiments, using microcosms with natural field soil water conditions, the addition of water, and the addition of mineral salts solution. Methanotroph population diversity was studied by targeting 16S rRNA and pmoA genes. Clone library analyses, denaturing gradient gel electrophoresis fingerprinting, and pmoA microarray hybridization analyses were carried out. Most methanotroph diversity (type I and type II methanotrophs) was observed in nonamended SIP microcosms. Although this treatment probably best reflected the in situ environmental conditions, one major disadvantage of this incubation was that the incorporation of 13CH4 was slow and some cross-feeding of 13C occurred, thereby leading to labeling of nonmethanotroph microorganisms. Conversely, microcosms supplemented with mineral salts medium exhibited rapid consumption of 13CH4, resulting in the labeling of a less diverse population of only type I methanotrophs. DNA-SIP incubations using water-amended microcosms yielded faster incorporation of 13C into active methanotrophs while avoiding the cross-feeding of 13C.

scholarly journals Identification of Acetate-Assimilating Microorganisms under Methanogenic Conditions in Anoxic Rice Field Soil by Comparative Stable Isotope Probing of RNA

2006 ◽  
Vol 73 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Tomoyuki Hori ◽  
Matthias Noll ◽  
Yasuo Igarashi ◽  
Michael W. Friedrich ◽  
Ralf Conrad
Keyword(s):  
Stable Isotope ◽  
Rice Field ◽  
Ferric Iron ◽  
Stable Isotope Probing ◽  
Polymorphism Analysis ◽  
Field Soil ◽  
Bacterial Populations ◽  
Density Fractions ◽  
Reverse Transcription Pcr ◽  
Rice Field Soil

ABSTRACT Acetate is the most abundant intermediate of organic matter degradation in anoxic rice field soil and is converted to CH4 and/or CO2. Aceticlastic methanogens are the primary microorganisms dissimilating acetate in the absence of sulfate and reducible ferric iron. In contrast, very little is known about bacteria capable of assimilating acetate under methanogenic conditions. Here, we identified active acetate-assimilating microorganisms by using a combined approach of frequent label application at a low concentration and comparative RNA-stable isotope probing with 13C-labeled and unlabeled acetate. Rice field soil was incubated anaerobically at 25°C for 12 days, during which 13C-labeled acetate was added at a concentration of 500 μM every 3 days. 13C-labeled CH4 and CO2 were produced from the beginning of the incubation and accounted for about 60% of the supplied acetate 13C. RNA was extracted from the cells in each sample taken and separated by isopycnic centrifugation according to molecular weight. Bacterial and archaeal populations in each density fraction were screened by reverse transcription-PCR-mediated terminal restriction fragment polymorphism analysis. No differences in the bacterial populations were observed throughout the density fractions of the unlabeled treatment. However, in the heavy fractions of the 13C treatment, terminal restriction fragments (T-RFs) of 161 bp and 129 bp in length predominated. These T-RFs were identified by cloning and sequencing of 16S rRNA as from a Geobacter sp. and an Anaeromyxobacter sp., respectively. Apparently these bacteria, which are known as dissimilatory iron reducers, were able to assimilate acetate under methanogenic conditions, i.e., when CO2 was the predominant electron acceptor. We hypothesize that ferric iron minerals with low bioavailability might have served as electron acceptors for Geobacter spp. and Anaeromyxobacter spp. under these conditions.

scholarly journals Characterization of growing bacterial populations in McMurdo Dry Valley soils through stable isotope probing with18O-water

2014 ◽  
Vol 89 (2) ◽  
pp. 415-425 ◽  
Author(s):  
Egbert Schwartz ◽  
David J. Van Horn ◽  
Heather N. Buelow ◽  
Jordan G. Okie ◽  
Michael N. Gooseff ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Probing ◽  
Bacterial Populations ◽  
Dry Valley

scholarly journals Diversity of Anaerobic Microorganisms Involved in Long-Chain Fatty Acid Degradation in Methanogenic Sludges as Revealed by RNA-Based Stable Isotope Probing

2007 ◽  
Vol 73 (13) ◽  
pp. 4119-4127 ◽  
Author(s):  
Masashi Hatamoto ◽  
Hiroyuki Imachi ◽  
Yuto Yashiro ◽  
Akiyoshi Ohashi ◽  
Hideki Harada
Keyword(s):  
Fatty Acid ◽  
Stable Isotope ◽  
Major Fatty Acid ◽  
Stable Isotope Probing ◽  
Chain Fatty Acid ◽  
Long Chain Fatty Acid ◽  
Bacterial Populations ◽  
Anaerobic Microorganisms ◽  
Degrading Bacteria ◽  
Long Chain

ABSTRACT Long-chain fatty acid (LCFA) degradation is a key step in methanogenic treatment of wastes/wastewaters containing high concentrations of lipids. However, despite the importance of LCFA-degrading bacteria, their natural diversity is little explored due to the limited availability of isolate information and the lack of appropriate molecular markers. We therefore investigated these microbes by using RNA-based stable isotope probing. We incubated four methanogenic sludges (mesophilic sludges MP and MBF and thermophilic sludges TP and JET) with 13C-labeled palmitate (1 mM) as a substrate. After 8 to 19 days of incubation, we could detect 13C-labeled bacterial rRNA. A density-resolved terminal restriction fragment length polymorphism fingerprinting analysis showed distinct bacterial populations in 13C-labeled and unlabeled rRNA fractions. The bacterial populations in the 13C-labeled rRNA fractions were identified by cloning and sequencing of reverse-transcribed 16S rRNA. Diverse phylogenetic bacterial sequences were retrieved, including those of members of the family Syntrophaceae, clone cluster MST belonging to the class Deltaproteobacteria, Clostridium clusters III and IV, phylum Bacteroidetes, phylum Spirochaetes, and family Syntrophomonadaceae. Although Syntrophomonadaceae species are considered to be the major fatty acid-degrading syntrophic microorganisms under methanogenic conditions, they were detected in only two of the clone libraries. These results suggest that phylogenetically diverse bacterial groups were active in situ in the degradation of LCFA under methanogenic conditions.

scholarly journals Identification of the Functionally Active Methanotroph Population in a Peat Soil Microcosm by Stable-Isotope Probing

2002 ◽  
Vol 68 (3) ◽  
pp. 1446-1453 ◽  
Author(s):  
Samantha A. Morris ◽  
Stefan Radajewski ◽  
Toby W. Willison ◽  
J. Colin Murrell
Keyword(s):  
Stable Isotope ◽  
Gradient Centrifugation ◽  
Peat Soil ◽  
Pcr Amplification ◽  
Cesium Chloride ◽  
Stable Isotope Probing ◽  
Soil Microcosm ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Type I

ABSTRACT The active population of low-affinity methanotrophs in a peat soil microcosm was characterized by stable-isotope probing. “Heavy” 13C-labeled DNA, produced after microbial growth on 13CH4, was separated from naturally abundant 12C-DNA by cesium chloride density gradient centrifugation and used as a template for the PCR. Amplification products of 16S rRNA genes and pmoA, mxaF, and mmoX, which encode key enzymes in the CH4 oxidation pathway, were analyzed. Sequences related to extant type I and type II methanotrophs were identified, indicating that these methanotrophs were active in peat exposed to 8% (vol/vol) CH4. The 13C-DNA libraries also contained clones that were related to β-subclass Proteobacteria, suggesting that novel groups of bacteria may also be involved in CH4 cycling in this soil.

scholarly journals Detection of Active Butyrate-Degrading Microorganisms in Methanogenic Sludges by RNA-Based Stable Isotope Probing

2008 ◽  
Vol 74 (11) ◽  
pp. 3610-3614 ◽  
Author(s):  
Masashi Hatamoto ◽  
Hiroyuki Imachi ◽  
Yuto Yashiro ◽  
Akiyoshi Ohashi ◽  
Hideki Harada
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Probing ◽  
Bacterial Populations ◽  
Degrading Bacteria

ABSTRACT Butyrate-degrading bacteria in four methanogenic sludges were studied by RNA-based stable isotope probing. Bacterial populations in the 13C-labeled rRNA fractions were distinct from unlabeled fractions, and Syntrophaceae species, Tepidanaerobacter sp., and Clostridium spp. dominated. These results suggest that diverse microbes were active in butyrate degradation under methanogenic conditions.

scholarly journals RNA–Stable-Isotope Probing Shows Utilization of Carbon from Inulin by Specific Bacterial Populations in the Rat Large Bowel

2014 ◽  
Vol 80 (7) ◽  
pp. 2240-2247 ◽  
Author(s):  
Gerald W. Tannock ◽  
Blair Lawley ◽  
Karen Munro ◽  
Ian M. Sims ◽  
Julian Lee ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Bacterial Species ◽  
Buoyant Density ◽  
Stable Isotope Probing ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Bacterial Cells ◽  
Bacterial Populations ◽  
Content Type ◽  
And Function

ABSTRACTKnowledge of the trophisms that underpin bowel microbiota composition is required in order to understand its complex phylogeny and function. Stable-isotope (13C)-labeled inulin was added to the diet of rats on a single occasion in order to detect utilization of inulin-derived substrates by particular members of the cecal microbiota. Cecal digesta from Fibruline-inulin-fed rats was collected prior to (0 h) and at 6, 12, 18 and 24 h following provision of the [13C]inulin diet. RNA was extracted from these cecal specimens and fractionated in isopycnic buoyant density gradients in order to detect13C-labeled nucleic acid originating in bacterial cells that had metabolized the labeled dietary constituent. RNA extracted from specimens collected after provision of the labeled diet was more dense than 0-h RNA. Sequencing of 16S rRNA genes amplified from cDNA obtained from these fractions showed thatBacteroides uniformis,Blautia glucerasea,Clostridium indolis, andBifidobacterium animaliswere the main users of the13C-labeled substrate. Culture-based studies of strains of these bacterial species enabled trophisms associated with inulin and its hydrolysis products to be identified.B. uniformisutilized Fibruline-inulin for growth, whereas the other species used fructo-oligosaccharide and monosaccharides. Thus, RNA–stable-isotope probing (RNA-SIP) provided new information about the use of carbon from inulin in microbiota metabolism.

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