Project description:We report here the RNA seq results of sRNA enriched Paracoccus denitrificans grown under three different N2O levels (high N2O reffered to as CuL/ low N2O reffered to as CuH/ Low N2O aerobic reffered to as CuH O2)
Project description:The effects of ocean acidification (OA) on nitrous oxide (N2O) production and on the community composition of ammonium oxidising archaea (AOA) were examined in the northern and southern sub-polar and polar Atlantic Ocean. Two research cruises were performed during June 2012 between the North Sea and Arctic Greenland and Barent Seas, and in January-February 2013 to the Antarctic Scotia Sea. Seven stations were occupied in all during which shipboard experimental manipulations of the carbonate chemistry were performed through additions of NaHCO3- + HCl in order to examine the impact of short- term (48 hour for N2O and between 96 and 168 hour for AOA) exposure to control and elevated conditions of OA. During each experiment, triplicate incubations were performed at ambient conditions and at 3 lowered levels of pH which varied between 0.06 and 0.4 units according to the total scale and which were targeted at CO2 partial pressures of ~500, 750 and 1000 μatm. The AOA assemblage in both Arctic and Antarctic regions was dominated by two major archetypes that represent the marine AOA clades most often detected in seawater. There were no significant changes in AOA assemblage composition between the beginning and end of the incubation experiments. N2O production was sensitive to decreasing pHT at all stations and decreased by between 2.4 and 44% with reduced pHT values of between 0.06 and 0.4. The reduction in N2O yield from nitrification was directly related to a decrease of between 28 and 67% in available NH3 as a result of the pH driven shift in the NH3:NH4+ equilibrium. The maximum reduction in N2O production at conditions projected for the end of the 21st century was estimated to be 0.82 Tg N y-1.
Project description:A culture of the hydrothermal vent bacterium Nitrosophilus labii HRV44T was grown with N2O to investigate molecular mechanisms of N2O-based respiration. Limited sample sizes were collected at 0 hours (before N2O addition to the culture headspace) and at 3, 6, and 24 hours after N2O addition.
Project description:The majority of potent greenhouse gas nitrous oxide (N2O) emissions originate from microbially mediated reactions. The enzyme N2O reductase is the only known biological N2O sink and has evolved in two phylogenetically distinct lineages (clades I and II). Clade II is of particular interest for biotechnology as it is often associated with non-denitrifying N2O reducers. In this study, Laureni et al. investigated the environmental conditions that select for clade II. To do so, we enriched two N2O-respiring communities at low dilution rates, under both electron donor (acetate) and electron acceptor (N2O) limitations, in order to assess the impact of substrate affinity and N2O cytotoxicity on community assembly. We used a combination of genome-resolved metagenomics and shotgun metaproteomics to identify the taxonomy and metabolic potential of the steady-state community members. Corresponding author: Michele Laureni, contact: m.laureni@tudelft.nl
Project description:The goal of this study was to use global gene expression as a diagnostic tool to compare hepatic gene expression patterns in both male and female FHM in streams with the lowest and highest reproductive success, and potentially identify a suite of mRNA transcripts indicative of reproduction in a population The goal of this study was to compare differences in hepatic mRNA expression between gender at high and low egg-producing streams, not differences between individual streams. A k-means cluster analysis was performed using eggs/pair/day on the original 17 streams to delineate 3 clusters: high, medium and low. From that analysis, FHM from 6 of the original 17-streams used in Crago et al. (2010) were chosen for the microarray experiment (Fig. 1, Table 1). In this study the experimental condition is reproductive success; High versus Low reproductive success. The streams grouped into High Reproductive Success were Oak Creek-2007 (2313 eggs), Point Creek (1277 eggs), Meeme Creek (1164 eggs) and Baird Creek (967 eggs). The streams grouped into Low Reproductive Success were: Ashwaubenon Creek (0 eggs), Devils Creek (541 eggs) and Oak Creek-2006 (642 eggs). Multiple regression analysis using the 22 sediment and water quality characteristics measured in the 6 streams with the highest (n = 4 and lowest (n = 3) streams demonstrated that there were no differences amongst the streams in regards to measure sediment and water variables. .5 One array was run for each gender from each stream. So that Males from Point Creek were pooled and run on one array, males from Ashwaubenon Creek were run on a separate array, and so forth. There were 14 arrays used in this study, 7 for males, 7 for females from individual rivers. So that Males from Point Creek were pooled and run on one array, males from Ashwaubenon Creek were run on a separate array, and so forth. In the case of Oak Creek, which was sampled in both years, there was a large difference in egg production between two years. Therefore separate arrays were run for Oak Creek 2006 and Oak Creek 2007. All streams chosen had overall survival rates of at least 80% through the 21-day sampling period, except Devils River. The survival rate for Devils River was at 100% until four days prior to the end of the experiment when six fish died or escaped.
Project description:(Meta)proteomics analyses were performed with cells collected from the Sab enrichment culture grown with N2O. Growth of Desulfitobacterium sp. strain Sab5 only occurred when N2O was supplied as electron acceptor, and biomass from cultures grown without N2O was not included in the analysis. Comparative proteomics analyses were performed with axenic Sporomusa acidovorans DSM3132 T cells grown with and without N2O.
Project description:Bradyrhizobia are common members of soil microbiomes and known as N2-fixing symbionts of economically important legumes. Many are also denitrifiers, which can act as sinks or sources for N2O. Inoculation with compatible rhizobia is often needed for optimal N2-fixation, but the choice of inoculant may have consequences for N2O emission. Here, we determined the phylogeny and denitrification capacity of Bradyrhizobium strains, most of them isolated from peanut-nodules. Analyses of genomes and denitrification end-points showed that all were denitrifiers, but only ~1/3 could reduce N2O. The N2O-reducing isolates had strong preference for N2O- over NO3--reduction. Such preference was also observed in a study of other bradyrhizobia and tentatively ascribed to competition between the electron pathways to Nap (periplasmic NO3- reductase) and Nos (N2O reductase). Another possible explanation is lower abundance of Nap than Nos. Here, proteomics revealed that Nap was instead more abundant than Nos, supporting the hypothesis that the electron pathway to Nos outcompetes that to Nap. In contrast, Paracoccus denitrificans, which has membrane-bond NO3- reductase (Nar), reduced N2O and NO3- simultaneously. We propose that the control at the metabolic level, favoring N2O reduction over NO3- reduction, applies also to other denitrifiers carrying Nos and Nap but lacking Nar.