In anoxic rice field soil, ferric iron reduction is one of the most important terminal electron accepting processes, yet little is known about the identity of iron-reducing microorganisms. Here, we identified acetate-metabolizing bacteria by RNA-based stable isotope probing in the presence of iron(III) oxides as electron acceptors. After reduction of endogenous iron(III) for 21 days, isotope probing with 13 C-labeled acetate (2 mM) and added ferric iron oxides (ferrihydrite or goethite) was performed in rice field soil slurries for 48 and 72 h. Ferrihydrite reduction coincided with a strong suppression of methanogenesis (77%). Extracted RNA from each treatment was density resolved by isopycnic centrifugation, and analyzed by terminal restriction fragment length polymorphism, followed by cloning and sequencing of 16S rRNA of bacterial and archaeal populations. In heavy, isotopically labeled RNAs of the ferrihydrite treatment, predominant 13 C-assimilating populations were identified as Geobacter spp. (B85% of all clones). In the goethite treatment, iron(II) formation was not detectable. However, Geobacter spp. (B30%), the d-proteobacterial Anaeromyxobacter spp. (B30%), and novel b-Proteobacteria were predominant in heavy rRNA fractions indicating that 13 C-acetate had been assimilated in the presence of goethite, whereas none were detected in the control heavy RNA. For the first time, active acetate-oxidizing iron(III)-reducing bacteria, including novel hitherto unrecognized populations, were identified as a functional guild in anoxic paddy soil.

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The manufacture of high mechanical strength cellulose‐based carbon fibers (CFs) is accomplished in a continuous process at comparably low temperatures and with high carbon yields. Applying a sulfur‐based carbonization agent, i.e., ammonium tosylate (ATS), carbon yields of 37% (83% of theory), and maximum tensile strengths and Young's moduli up to 2.0 and 84 GPa are obtained already at 1400 °C. For comparison, the use of the well‐known carbonization aid ammonium dihydrogenphosphate ((NH4)H2PO4), ADHP, is also investigated. Both the precursor and the CFs are characterized via elemental analysis, wide‐angle X‐ray scattering, Raman spectroscopy, scanning electron microscopy, and tensile testing. Thermogravimetric analysis coupled with mass spectrometry/infrared spectroscopy discloses differences in structure formation between ATS and ADHP‐derived CFs during pyrolysis.

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