Members » Maria Fabisch

@article{nokey,

title = {Mixotrophic Iron-Oxidizing Thiomonas Isolates from an Acid Mine Drainage-Affected Creek},

author = {Denise M. Akob and Michelle Hallenbeck and Felix Beulig and Maria Fabisch and Kirsten Küsel and Jessica L. Keffer and Tanja Woyke and Nicole Shapiro and Alla Lapidus Hans-Peter Klenk and Clara S. Chan},

doi = {10.1128/AEM.01424-20},

year  = {2020},

date = {2020-11-20},

urldate = {2020-11-20},

journal = {Applied and Environmental Microbiology},

volume = {86},

number = {24},

abstract = {Natural attenuation of heavy metals occurs via coupled microbial iron cycling and metal precipitation in creeks impacted by acid mine drainage (AMD). Here, we describe the isolation, characterization, and genomic sequencing of two iron-oxidizing bacteria (FeOB) species: Thiomonas ferrovorans FB-6 and Thiomonas metallidurans FB-Cd, isolated from slightly acidic (pH 6.3), Fe-rich, AMD-impacted creek sediments. These strains precipitated amorphous iron oxides, lepidocrocite, goethite, and magnetite or maghemite and grew at a pH optimum of 5.5. While Thiomonas spp. are known as mixotrophic sulfur oxidizers and As oxidizers, the FB strains oxidized Fe, which suggests they can efficiently remove Fe and other metals via coprecipitation. Previous evidence for Thiomonas sp. Fe oxidation is largely ambiguous, possibly because of difficulty demonstrating Fe oxidation in heterotrophic/mixotrophic organisms. Therefore, we also conducted a genomic analysis to identify genetic mechanisms of Fe oxidation, other metal transformations, and additional adaptations, comparing the two FB strain genomes with 12 other Thiomonas genomes. The FB strains fall within a relatively novel group of Thiomonas strains that includes another strain (b6) with solid evidence of Fe oxidation. Most Thiomonas isolates, including the FB strains, have the putative iron oxidation gene cyc2, but only the two FB strains possess the putative Fe oxidase genes mtoAB. The two FB strain genomes contain the highest numbers of strain-specific gene clusters, greatly increasing the known Thiomonas genetic potential. Our results revealed that the FB strains are two distinct novel species of Thiomonas with the genetic potential for bioremediation of AMD via iron oxidation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Interaction of the RcsB Response Regulator with Auxiliary Transcription Regulators in Escherichia coli},

author = {Derk Pannen and Maria Fabisch and Lisa Gausling and Karin Schnetz},

doi = {10.1074/jbc.M115.696815},

year  = {2015},

date = {2015-12-03},

urldate = {2015-12-03},

journal = {Journal of Biological Chemistry},

volume = {291},

issue = {5},

pages = {2357-2370},

abstract = {The Rcs phosphorelay is a two-component signal transduction system that is induced by cell envelope stress. RcsB, the response regulator of this signaling system, is a pleiotropic transcription regulator, which is involved in the control of various stress responses, cell division, motility, and biofilm formation. RcsB regulates transcription either as a homodimer or together with auxiliary regulators, such as RcsA, BglJ, and GadE in Escherichia coli. In this study, we show that RcsB in addition forms heterodimers with MatA (also known as EcpR) and with DctR. Our data suggest that the MatA-dependent transcription regulation is mediated by the MatA-RcsB heterodimer and is independent of RcsB phosphorylation. Furthermore, we analyzed the relevance of amino acid residues of the active quintet of conserved residues, and of surface-exposed residues for activity of RcsB. The data suggest that the activity of the phosphorylation-dependent dimers, such as RcsA-RcsB and RcsB-RcsB, is affected by mutation of residues in the vicinity of the phosphorylation site, suggesting that a phosphorylation-induced structural change modulates their activity. In contrast, the phosphorylation-independent heterodimers BglJ-RcsB and MatA-RcsB are affected by only very few mutations. Heterodimerization of RcsB with various auxiliary regulators and their differential dependence on phosphorylation add an additional level of control to the Rcs system that is operating at the output level.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Dominance of ‘Gallionella capsiferriformans’ and heavy metal association with Gallionella-like stalks in metal-rich pH 6 mine water discharge},

author = {Maria Fabisch and Gina Freyer and Carol A. Johnson and G. Büchel and Denise M. Akob and R. Neu and Kirsten Küsel},

doi = {10.1111/gbi.12162},

year  = {2015},

date = {2015-09-26},

urldate = {2015-09-26},

journal = {Geobiology },

volume = {14},

issue = {1},

pages = {68-90},

abstract = {Heavy metal-contaminated, pH 6 mine water discharge created new streams and iron-rich terraces at a creek bank in a former uranium-mining area near Ronneburg, Germany. The transition from microoxic groundwater with ~5 mm Fe(II) to oxic surface water may provide a suitable habitat for microaerobic iron-oxidizing bacteria (FeOB). In this study, we investigated the potential contribution of these FeOB to iron oxidation and metal retention in this high-metal environment. We (i) identified and quantified FeOB in water and sediment at the outflow, terraces, and creek, (ii) studied the composition of biogenic iron oxides (Gallionella-like twisted stalks) with scanning and transmission electron microscopy (SEM, TEM) as well as confocal laser scanning microscopy (CLSM), and (iii) examined the metal distribution in sediments. Using quantitative PCR, a very high abundance of FeOB was demonstrated at all sites over a 6-month study period. Gallionella spp. clearly dominated the communities, accounting for up to 88% of Bacteria, with a minor contribution of other FeOB such as Sideroxydans spp. and ‘Ferrovum myxofaciens’. Classical 16S rRNA gene cloning showed that 96% of the Gallionella-related sequences had ≥97% identity to the putatively metal-tolerant ‘Gallionella capsiferriformans ES-2’, in addition to known stalk formers such as Gallionella ferruginea and Gallionellaceae strain R-1. Twisted stalks from glass slides incubated in water and sediment were composed of the Fe(III) oxyhydroxide ferrihydrite, as well as polysaccharides. SEM and scanning TEM-energy-dispersive X-ray spectroscopy revealed that stalk material contained Cu and Sn, demonstrating the association of heavy metals with biogenic iron oxides and the potential for metal retention by these stalks. Sequential extraction of sediments suggested that Cu (52–61% of total sediment Cu) and other heavy metals were primarily bound to the iron oxide fractions. These results show the importance of ‘G. capsiferriformans’ and biogenic iron oxides in slightly acidic but highly metal-contaminated freshwater environments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Observations and assessment of iron oxide and green rust nanoparticles in metal-polluted mine drainage within a steep redox gradient},

author = {Carol A. Johnson and Gina Freyer and Maria Fabisch and Manuela A. Caraballo and Kirsten Küsel and Michael F. Hochella Jr},

doi = {10.1071/EN13184},

year  = {2014},

date = {2014-05-19},

urldate = {2014-05-19},

journal = {Environmental Chemistry },

volume = {11},

issue = {4},

pages = {377-391},

abstract = {In this study of iron- and silica-bearing nanoparticle and colloid aggregates in slightly acidic mine drainage, we combined bulk scale geochemistry techniques with detailed nanoscale analyses using high-resolution transmission electron microscopy (HR-TEM) to demonstrate the complexity of iron oxide formation and transformation at a steep redox gradient (groundwater outflow into a stream), and the resulting role in metal(loid) uptake. We also identified pseudohexagonal nanosheets of Zn-bearing green rust in outflowing groundwater using HR-TEM. This is only the second study where green rust was identified in groundwater, and the second to examine naturally occurring green rust with analytical TEM. In aerated downstream waters, we found aggregates of poorly crystalline iron oxide particles (20–200 nm in diameter). Inductively coupled plasma–mass spectrometry (ICP-MS) analysis of water fractions shows that most elements such as Ni and Zn were found almost exclusively in the dissolved–nanoparticulate (<0.1 μm) fraction, whereas Cu and As were primarily associated with suspended particles. In the underlying sediments composed of deposited particles, goethite nanoneedles formed on the ferrihydrite surfaces of larger aggregated particles (100–1000 nm), resulting in more reactive surface area for metal(loid) uptake. Sequential extraction of sediments showed that many metal(loid)s, particularly As and Zn, were associated with iron oxides identified as ferrihydrite, goethite and possibly schwertmannite. Amorphous silica co-precipitation with iron oxides was prevalent at all sampling sites, but its effect on metal(loid) sorption is unknown. Fine-grained iron oxide sediments are easily remobilised during turbulent flow events, adding to the mobility of the associated metals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Surprising abundance of Gallionella-related iron oxidizers in creek sediments at pH 4.4 or at high heavy metal concentrations},

author = {Maria Fabisch and Felix Beulig and Denise M. Akob and Kirsten Küsel},

doi = {10.3389/fmicb.2013.00390},

year  = {2013},

date = {2013-12-18},

urldate = {2013-12-18},

journal = {Frontiers in Microbiology},

volume = {4},

abstract = {We identified and quantified abundant iron-oxidizing bacteria (FeOB) at three iron-rich, metal-contaminated creek sites with increasing sediment pH from extremely acidic (R1, pH 2.7), to moderately acidic (R2, pH 4.4), to slightly acidic (R3, pH 6.3) in a former uranium-mining district. The geochemical parameters showed little variations over the 1.5 year study period. The highest metal concentrations found in creek sediments always coincided with the lowest metal concentrations in creek water at the slightly acidic site R3. Sequential extractions of R3 sediment revealed large portions of heavy metals (Ni, Cu, Zn, Pb, U) bound to the iron oxide fraction. Light microscopy of glass slides exposed in creeks detected twisted stalks characteristic of microaerobic FeOB of the family Gallionellaceae at R3 but also at the acidic site R2. Sequences related to FeOB such as Gallionella ferruginea, Sideroxydans sp. CL21, Ferritrophicum radicicola, and Acidovorax sp. BrG1 were identified in the sediments. The highest fraction of clone sequences similar to the acidophilic “Ferrovum myxofaciens” was detected in R1. Quantitative PCR using primer sets specific for Gallionella spp., Sideroxydans spp., and “Ferrovum myxofaciens” revealed that ~72% (R2 sediment) and 37% (R3 sediment) of total bacterial 16S rRNA gene copies could be assigned to groups of FeOB with dominance of microaerobic Gallionella spp. at both sites. Gallionella spp. had similar and very high absolute and relative gene copy numbers in both sediment communities. Thus, Gallionella-like organisms appear to exhibit a greater acid and metal tolerance than shown before. Microaerobic FeOB from R3 creek sediment enriched in newly developed metal gradient tubes tolerated metal concentrations of 35 mM Co, 24 mM Ni, and 1.3 mM Cd, higher than those in sediments. Our results will extend the limited knowledge of FeOB at contaminated, moderately to slightly acidic environments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}