Efficient Bioelectrochemical Conversion of Industrial Wastewater by Specific Strain Isolation and Community Adaptation

The aim of this study was the development of a specifically adapted microbial community for the removal of organic carbon from an industrial wastewater using a bioelectrochemical system. In a first step, ferric iron reducing microorganisms were isolated from the examined industrial wastewater. In a second step, it was tested to what extent these isolates or a cocultivation of the isolates with the exoelectrogenic model organism Geobacter sulfurreducens (G. sulfurreducens) were able to eliminate organic carbon from the wastewater. To establish a stable biofilm on the anode and to analyze the performance of the system, the experiments were conducted first under batch-mode conditions for 21 days. Since the removal of organic carbon was relatively low in the batch system, a similar experiment was conducted under continuous-mode conditions for 65 days, including a slow transition from synthetic medium to industrial wastewater as carbon and electron source and variations in the flow rate of the medium. The overall performance of the system was strongly increased in the continuous- compared to the batch-mode reactor and the highest average current density (1,368 mA/m2) and Coulombic efficiency (54.9%) was measured in the continuous-mode reactor inoculated with the coculture consisting of the new isolates and G. sulfurreducens. The equivalently inoculated batch-mode system produced only 82-fold lower current densities, which were accompanied by 42-fold lower Coulombic efficiencies

Live Imaging of Xwnt5A-ROR2 Complexes

Secreted molecules of the Wnt family regulate key decisions in embryogenesis and adult tissue homeostasis by activating a complex network of Wnt signaling pathways. Although the different branches of Wnt signaling have been studied for more than 25 years, fluorophore tagged constructs for live cell imaging of Wnt molecules activating the Wnt/β-catenin pathway have become available only recently. We have generated a fluorophore tagged Wnt construct of the Xenopus Wnt5a protein (Xwnt5A) with the enhanced green fluorescent protein (EGFP), Xwnt5A-EGFP. This construct activates non-canonical Wnt pathways in an endocytosis dependent manner and is capable of compensating for the loss of endogenous Xwnt5A in Xenopus embryos. Strikingly, non-canonical Wnt pathway activation was restricted to short-range signaling while an inhibitory effect was observed in transwell cell cultures taken as long-range signaling model sytem. We used our Xwnt5A-EGFP construct to analyze in vivo binding of Wnt5A to its co-receptor ROR2 on the microscopic and on the molecular level. On the microscopic level, Xwnt5A-EGFP clusters in the membrane and recruits ROR2-mCherry to these clusters. Applying dual-colour dual-focus line-scanning fluorescence correlation spectroscopy on dorsal marginal zone explants, we identified membrane tethered Xwnt5A-EGFP molecules binding to ROR2-mCherry molecules. Our data favour a model, in which membrane-tethered Wnt-5A recruits ROR2 to form large ligand/receptor clusters and signals in an endocytosis-dependent manner

Xwnt5A-EGFP but not ROR2-mCherry clusters in membranes of DMZ cells.

<p>A) 150 pg of Xwnt5A-EGFP mRNA were co-injected with 125 pg membrane-anchored (growth-associated protein 43 (Gap43))-mCherry as a lineage tracer in the two dorsal blastomeres of eight-cell stage embryos. At stage 10.25, dorsal marginal zones were explanted and analyzed for subcellular localization of the Xwnt5A-EGFP protein. Prominent Xwnt5A-EGFP clusters localized at the membrane of DMZ cells at the onset (stage 10.5) and end (stage 12) of gastrulation. Shown are snapshots of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109428#pone.0109428.s003" target="_blank">movies S1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109428#pone.0109428.s004" target="_blank">S2</a>. B) 40 pg ROR2-mCherry were injected into the two dorsal blastomeres of eight-cell stage embryos. ROR2-mCherry is homogenously distributed at the membrane of DMZ explants throughout gastrulation. Shown are snapshots of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109428#pone.0109428.s005" target="_blank">movies S3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109428#pone.0109428.s006" target="_blank">S4</a>.</p

Xwnt5A induces clustering of ROR2.

<p>A) 150 pg of Xwnt5A-EGFP mRNA were co-injected with 40 pg of the ROR2-mCherry in the two dorsal blastomeres of eight-cell stage embryos. At stage 10.25 dorsal marginal zones were explanted and analyzed for subcellular localization of the Xwnt5A-EGFP and ROR2-mCherry. Prominent Xwnt5A-EGFP clusters co-localize with ROR2-mCherry clusters at the membrane of DMZ cells. These clusters are found at the onset (stage 10.5) and at the end (stage 12) of gastrulation. Shown are snapshots of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109428#pone.0109428.s007" target="_blank">movies S5</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109428#pone.0109428.s008" target="_blank">S6</a>. B) 150 pg of Xwnt5A-EGFP mRNA were co-injected with 1.6 pmol Xwnt-5A specific antisense morpholino and 125 pg Gap43-mCherry. Also in these Xwnt-5A-depleted explants Xwnt5A-EGFP clustered in the membrane.</p

Long-range Wnt-5A inhibits the ATF2-Luc reporter.

<p>A) For studying long-range signaling, Xwnt5A-EGFP transfected HEK293 cells seeded on thinCerts TC chambers were transferred on cells transfected with the ATF2-Luc reporter and cultivated for additional 24 hours. To investigate paracrine signaling, cells transfected with Xwnt5A-EGFP were co-cultured with cells transfected with the ATF2-Luc reporter for 24 hours. To analyze both autocrine and paracrine signaling, the reporter and the Wnt ligand were cotransfected. B) Activation of the non-canonical Wnt reporter ATF2-Luc by co-transfected Wnt8, Wnt11 and Wnt5A. C) Activation of the non-canonical Wnt reporter ATF2-Luc by long-range Wnt8, Wnt11 and Wnt5A in a two-chamber assay. D) Xwnt5A-EGFP triggered ATF2-Luc activation depends on endocytosis. Wnt5A induced ATF2-Luc activation (cotransfection) was inhibited by addition of 5 µg/ml chlorpromazine (Chlo) and 150 µM genistein (Gen) 24 h before the measurement. Given are the mean values ± standard errors and the p-values according to Student's t-test, ns: not significant, n gives the number of transfections.</p