Project description:Comparative transcriptomic analysis between methane- and methane plus xylose- grown cultures revealed different transcriptional responses of pXyl M. alcaliphilum 20Z strain on diffirent growth modes.
Project description:Here we present the assembled genome of the facultative methanotroph, Methylocystis strain SB2, along with assessment of its transcriptome when grown on methane vs. ethanol. As expected, transcriptomic analyses indicate methane is converted to carbon dioxide via the canonical methane oxidation pathway for energy generation, and that carbon is assimilated at the level of formaldehyde via the serine cycle. When grown on ethanol, it appears this strain converts ethanol to acetyl-CoA and then utilizes the TCA cycle for energy generation and the ethylmalonyl CoA pathway for the production of biomass. All cultures were grown in triplicates for subsequent DNA and RNA extraction as well as for subsequent sequencing using Illumina. Transcriptomic analysis results presented in this Series.
Project description:Our goal is to convert methane efficiently into liquid fuels that may be more readily transported. Since aerobic oxidation of methane is less efficient, we focused on anaerobic processes to capture methane, which are accomplished by anaerobic methanotrophic archaea (ANME) in consortia. However, no pure culture capable of oxidizing and growing on methane anaerobically has been isolated. In this study, Methanosarcina acetivorans, an archaeal methanogen, was metabolically engineered to take up methane, rather than to generate it. To capture methane, we cloned the DNA coding for the enzyme methyl-coenzyme M reductase (Mcr) from an unculturable archaeal organism from a Black Sea mat into M. acetivorans to effectively run methanogenesis in reverse. The engineered strain produces primarily acetate, and our results demonstrate that pure cultures can grow anaerobically on methane.
Project description:Methanotrophs, which help regulate atmospheric levels of methane, are active in diverse natural and man-made environments. This range of habitats and the feast-famine cycles seen by many environmental methanotrophs suggest that methanotrophs dynamically mediate rates of methane oxidation. Global methane budgets require ways to account for this variability in time and space. Functional gene biomarker transcripts are increasingly being studied to inform the dynamics of diverse biogeochemical cycles. Previously, per-cell transcript levels of the methane oxidation biomarker, pmoA, were found to vary quantitatively with respect to methane oxidation rates in model aerobic methanotroph, Methylosinus trichosporium OB3b. In the present study, these trends were explored for two additional aerobic methanotroph pure cultures, Methylocystis parvus OBBP and Methylomicrobium album BG8. At steady-state conditions, per cell pmoA mRNA transcript levels strongly correlated with per cell methane oxidation across the three methanotrophs across many orders of magnitude of activity (R2 = 0.91). Additionally, genome-wide expression data (RNA-seq) were used to explore transcriptomic responses of steady state M. album BG8 cultures to short-term CH4 and O2 limitation. These limitations induced regulation of genes involved in central carbon metabolism (including carbon storage), cell motility, and stress response.
Project description:Our goal is to convert methane efficiently into liquid fuels that may be more readily transported. Since aerobic oxidation of methane is less efficient, we focused on anaerobic processes to capture methane, which are accomplished by anaerobic methanotrophic archaea (ANME) in consortia. However, no pure culture capable of oxidizing and growing on methane anaerobically has been isolated. In this study, Methanosarcina acetivorans, an archaeal methanogen, was metabolically engineered to take up methane, rather than to generate it. To capture methane, we cloned the DNA coding for the enzyme methyl-coenzyme M reductase (Mcr) from an unculturable archaeal organism from a Black Sea mat into M. acetivorans to effectively run methanogenesis in reverse. The engineered strain produces primarily acetate, and our results demonstrate that pure cultures can grow anaerobically on methane. Differential gene analysis of two growth conditions (three biological replicates each) was performed: (i) M. acetivorans/pES1-MATmcr3 grown on methane and (ii) M. acetivorans/pES1-MATmcr3 grown on methanol. All starter cultures (200 mL) were grown on methanol for 5 days, and harvested by centrifugation. Cell pellets were washed three times with HS medium, and resuspended using 5 mL HS medium, 2 µg/mL puromycin, and 0.1 mM FeCl3. For condition (i), methane was filled into the headspace of the cultures. For condition (ii), 150 mM methanol was added. All cultures were incubated at 37C for 5 days, followed by rapid centrifugation in the presence of 50 µL RNAlater solution (Ambion, Austin, TX) per mL of culture. Total RNA was isolated using RNeasy Mini kit (Qiagen, Valencia, CA) were then digested with terminator 5â-phosphate-dependent exonuclease (Epicentre, Madison, WI) to partially remove ribosomal RNA. Digested RNA were cleaned up using AgenCourt RNAClean XP beads (AgenCourt Bioscience, Beverly, MA) and used for cDNA library construction using the TruSeq Stranded mRNA Library kit (Illumina). Pooled and barcoded cDNA library was then sequenced on a HiSeq sequencing platform (Illumina). Obtained reads were mapped to the reference genome of M. acetivorans (Genbank accession NC_003552.1) using STAR. The mapped reads were assembled using Cufflink v2.2.1 to identify potential novel transcripts. Assembled, unannotated novel transcripts for all the strains were combined with the list of known genes. Differential expression of genes and potential novel transcripts were determined using Cuffdiff at a significance cutoff at q < 0.07 with a false discovery rate of 0.05. Expression levels of gene transcripts are expressed as fragments per kilobase of transcript per million mapped fragments (FPKM), and expression changes are determined by the ratio of FPKM of culture replicates grown on methane to FPKM of culture replicates grown on methanol.
Project description:Here we present the assembled genome of the facultative methanotroph, Methylocystis strain SB2, along with assessment of its transcriptome when grown on methane vs. ethanol. As expected, transcriptomic analyses indicate methane is converted to carbon dioxide via the canonical methane oxidation pathway for energy generation, and that carbon is assimilated at the level of formaldehyde via the serine cycle. When grown on ethanol, it appears this strain converts ethanol to acetyl-CoA and then utilizes the TCA cycle for energy generation and the ethylmalonyl CoA pathway for the production of biomass.
Project description:Aerobic methanotrophic bacteria use methane as their sole source of carbon and energy and serve as a major sink for the potent greenhouse gas methane in freshwater ecosystems. Despite this important environmental role, little is known about the molecular details of how these organisms interact in the environment. Many bacterial species use quorum sensing systems to regulate gene expression in a density-dependent manner. We have identified a quorum sensing system in the genome of Methylobacter tundripaludum, a dominant methane-oxidizer in methane enrichments of sediment from Lake Washington (Seattle, WA, USA). We determined that M. tundripaludum primarily produces N-3-hydroxydecanoyl-L-homoserine lactone (3-OH-C10-HSL) and that production is governed by a positive feedback loop. We then further characterized this system by determining which genes are regulated by quorum sensing in this methane-oxidizer using RNA-seq, and discovered this system regulates the expression of a novel nonribosomal peptide synthetase biosynthetic gene cluster. These results identify and characterize a mode of cellular communication in an aerobic methane-oxidizing bacterium.
2016-08-16 | GSE85617 | GEO
Project description:Microbial mat enrichment cultures