Project description:Biotransformation of soil organochlorine pesticides (OCP) is often impeded by a lack of nutrients relevant for bacterial growth and/or co-metabolic OCP biotransformation. By providing space-filling mycelia, fungi promote contaminant biodegradation by facilitating bacterial dispersal and the mobilization and release of nutrients in the mycosphere. We here tested whether mycelial nutrient transfer from nutrient-rich to nutrient-deprived areas facilitates bacterial OCP degradation in a nutrient-deficient habitat. The legacy pesticide hexachlorocyclohexane (HCH), a non-HCH-degrading fungus (Fusarium equiseti K3), and a co-metabolically HCH-degrading bacterium (Sphingobium sp. S8) isolated from the same HCH-contaminated soil were used in spatially structured model ecosystems. Using 13C-labelled fungal biomass and protein-based stable isotope probing (protein-SIP), we traced the incorporation of 13C fungal metabolites into bacterial proteins while simultaneously determining the biotransformation of the HCH isomers. The relative isotope abundance (RIA, 7.1 – 14.2%), labeling ratio (LR, 0.13 – 0.35), and the shape of isotopic mass distribution profiles of bacterial peptides indicated the transfer of 13C-labeled fungal metabolites into bacterial proteins. Distinct 13C incorporation into the haloalkane dehalogenase (linB) and 2,5-dichloro-2,5-cyclohexadiene-1,4-diol dehydrogenase (LinC), as key enzymes in metabolic HCH degradation, underpin the role of mycelial nutrient transport and fungal-bacterial interactions for co-metabolic bacterial HCH degradation in heterogeneous habitats. Nutrient uptake from mycelia increased HCH removal by twofold as compared to bacterial monocultures. Fungal-bacterial interactions hence may play an important role in the co-metabolic biotransformation of OCP or recalcitrant micropollutants (MPs).
Project description:Fourier transform ion cyclotron resonance (FT-ICR) and Orbitrap mass spectrometry (MS) are among the highest-performing analytical platforms in metabolomics. Their high mass measurement accuracy and mass resolving power enable detailed investigation of biological metabolomes. Non-targeted MS experiments, however, yield extremely complex datasets that make metabolite annotation very challenging, if not impossible. High-resolution accurate mass measurements greatly facilitate this process by reducing mass errors and spectral overlaps. When applied together with relative isotopic abundance (RIA) measurements, heuristic rules, and constraints during searches, the number of candidate elemental formula(s) can be significantly reduced. Here, we evaluate the performance of two leading analytical MS platforms, Orbitrap ID-X and 12T solariX FT-ICR mass spectrometers, in terms of mass accuracy and RIA measurements, and how these factors affect the assignment of the correct elemental formulae in metabolite annotation.
Project description:To investigate the transcriptional profile of GVE2 genes, the viral genes were identified by DNA microarray with Cy5- or Cy3-dUTP-labeled cDNAs prepared from uninfected and GVE2-infected Geobacillus sp. E263 at 4 h p.i.. After hybridization with the Cy3-dUTP-labeled cDNAs from GVE2-infected Geobacillus sp. E263 at 4 h p.i., Cy5-dUTP-labeled cDNAs from uninfected Geobacillus sp. E263 as well as Cy3- dUTP-labeled yeast cDNAs and Hex DNA, many spots produced positive signals significantly above the background, while no signal appeared for the Cy5-dUTP-labeled cDNAs from uninfected Geobacillus sp. E263., indicating that the positive signals represented the GVE2 gene transcripts detectable by DNA microarray. The DNA fragments, detected to be positive in the reverse transcripts at 4 h p.i., contained 74.2% of the presumptive GVE2 ORFs. Keywords: Transcriptional profile of thermophilic bacteriophage at 4 h p.i.
Project description:Fourier transform ion cyclotron resonance (FT-ICR) and Orbitrap mass spectrometry (MS) are among the highest-performing analytical platforms in metabolomics. Their high mass measurement accuracy and mass resolving power enable detailed investigation of biological metabolomes. Non-targeted MS experiments, however, yield extremely complex datasets that make metabolite annotation very challenging, if not impossible. High-resolution accurate mass measurements greatly facilitate this process by reducing mass errors and spectral overlaps. When applied together with relative isotopic abundance (RIA) measurements, heuristic rules, and constraints during searches, the number of candidate elemental formula(s) can be significantly reduced. Here, we evaluate the performance of two leading analytical MS platforms, Orbitrap ID-X and 12T solariX FT-ICR mass spectrometers, in terms of mass accuracy and RIA measurements, and how these factors affect the assignment of the correct elemental formulae in metabolite annotation. Quality of the mass measurements was evaluated under various experimental conditions (resolution: 120 K, 240 K, 500 K; automatic gain control: 5e4, 1e5, 5e5) for the Orbitrap MS platform.