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.
Project description:Custom made functional gene micoarray (E-FGA) consisting of 13,056 mRNA-enriched anonymus microbial clones from dirverse microbial communities to profile microbial gene transcript in agricultural soils with low and high flux of N2O. A total of 96 genes displayed expression that differed significantly between low and high N2O emitting soils. Creation and validation of an cDNA microarray from environmental microbial mRNA, to use as a monitoring tool for microbial gene expression Microbial expression profiles comparing two high N2O-emitting sites (3 soil replicates and microarrays each) and two low N2O-emitting sites (3 soil replicates and microarray each) from sugarcane site in Mackay, Australia
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)