Project description:The increased fitness when grown with pyruvate as carbon source in response to lanthanum supplementation was used as starting point to study genes induced in Beijerinckiaceae bacterium RH AL1 upon exposure to lanthanum.
Project description:Beijerinckiaceae bacterium RH AL1 was grown exponentially in with methanol (1% [v/v]) as carbon source and lanthanum (1µM) as necessary growth supplement. Harvested biomass was subjected to RNA extraction, mRNA-enrichment and Illumina sequencing library preparation for subsequent RNA-Seq analysis. The scope of this gene expression analysis was to validate the expression of genes linked to pathways that are involved in C1-metabolism.
Project description:Recent work with Methylorubrum extorquens AM1 identified intracellular, cytoplasmic lanthanide storage in an organism that harnesses these metals for its metabolism. Here, we describe the extracellular and intracellular accumulation of lanthanides in the Beijerinckiaceae bacterium RH AL1, a newly isolated and recently characterized methylotroph. Using ultrathin-section transmission electron microscopy (TEM), freeze fracture TEM (FFTEM), and energy-dispersive X-ray spectroscopy, we demonstrated that strain RH AL1 accumulates lanthanides extracellularly at outer membrane vesicles (OMVs) and stores them in the periplasm. High-resolution elemental analyses of biomass samples revealed that strain RH AL1 can accumulate ions of different lanthanide species, with a preference for heavier lanthanides. Its methanol oxidation machinery is supposedly adapted to light lanthanides, and their selective uptake is mediated by dedicated uptake mechanisms. Based on transcriptome sequencing (RNA-seq) analysis, these presumably include the previously characterized TonB-ABC transport system encoded by the lut cluster but potentially also a type VI secretion system. A high level of constitutive expression of genes coding for lanthanide-dependent enzymes suggested that strain RH AL1 maintains a stable transcript pool to flexibly respond to changing lanthanide availability. Genes coding for lanthanide-dependent enzymes are broadly distributed taxonomically. Our results support the hypothesis that central aspects of lanthanide-dependent metabolism partially differ between the various taxa. IMPORTANCE Although multiple pieces of evidence have been added to the puzzle of lanthanide-dependent metabolism, we are still far from understanding the physiological role of lanthanides. Given how widespread lanthanide-dependent enzymes are, only limited information is available with respect to how lanthanides are taken up and stored in an organism. Our research complements work with commonly studied model organisms and showed the localized storage of lanthanides in the periplasm. This storage occurred at comparably low concentrations. Strain RH AL1 is able to accumulate lanthanide ions extracellularly and to selectively utilize lighter lanthanides. The Beijerinckiaceae bacterium RH AL1 might be an attractive target for developing biorecovery strategies to obtain these economically highly demanded metals in environmentally friendly ways.
Project description:Transcriptome analysis of Beijerinckiaceae bacterium RH AL1 grown with pyruvate as the carbon source in response to lanthanum supplementation