title: Revealing the microbial community structure of clogging materials in dewatering wells differing in physico-chemical parameters in an open-cast mining area.
abstract: Iron rich deposits cause clogging the pumps and pipes of dewatering wells in open-cast mines, interfering with their function; however, little is known about either the microbial community structure or their potential role in the formation of these deposits. The microbial diversity and abundance of iron-oxidizing and -reducing bacteria were compared in pipe deposit samples with different levels of encrustation from 16 wells at three lignite mining sites. The groundwater varied in pH values from slightly acidic (4.5) to neutral (7.3), Fe(II) concentrations from 0.48 to 7.55 mM, oxygen content from 1.8 to 5.8 mg L(-1), and dissolved organic carbon (DOC) from 1.43 to 12.59 mg L(-1). There were high numbers of bacterial 16S rRNA gene copies in deposits, up to 2.5 × 10(10) copies g(-1) wet weight. Pyrosequencing analysis of bacterial 16S rRNA genes revealed that Proteobacteria was the most abundant phylum (63.3% of the total reads on average), followed by Actinobacteria (10.2%) and Chloroflexi (6.4%). Gallionella-related sequences dominated the bacterial community of pipe deposits and accounted for 48% of total sequence reads. Pipe deposits with amorphous ferrihydrite and schwertmannite mostly contained Gallionella (up to 1.51 × 10(10) 16S rRNA gene copies g(-1) wet weight), while more crystalline deposits showed a higher bacterial diversity. Surprisingly, the abundance of Gallionella was not correlated with groundwater pH, oxygen, or DOC content. Sideroxydans-related 16S rRNA gene copy numbers were one order of magnitude less than Gallionella, followed by acidophilic Ferrovum-related groups. Iron reducing bacteria were detected at rather low abundance, as was expected given the low iron reduction potential, although they could be stimulated by lactate amendment. The overall high abundance of Gallionella suggests that microbes may make major contributions to pipe deposit formation irrespective of the water geochemistry. Their iron oxidation activity might initiate the formation of amorphous iron oxides, potentially providing niches for other microorganisms later after crystallization, and leading to higher bacterial diversity along with deposit accumulation in later stages of clogging.
authors.affiliation: Aquatic Geomicrobiology, Friedrich Schiller University Jena, Dornburgerstr. 159, 07743 Jena, Germany.
authors.forename: Juanjuan
authors.initials: J
authors.lastname: Wang
authors.affiliation: Aquatic Geomicrobiology, Friedrich Schiller University Jena, Dornburgerstr. 159, 07743 Jena, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Sickinger
authors.affiliation: Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany.
authors.forename: Valerian
authors.initials: V
authors.lastname: Ciobota
authors.affiliation: Aquatic Geomicrobiology, Friedrich Schiller University Jena, Dornburgerstr. 159, 07743 Jena, Germany; German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Herrmann
authors.affiliation: Vattenfall Europe Mining AG, Vom-Stein-Straße 39, 03050 Cottbus, Germany.
authors.forename: Helfried
authors.initials: H
authors.lastname: Rasch
authors.affiliation: Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Rösch
authors.affiliation: Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany; Institute of Photonic Technology Jena, Albert-Einstein-Straße 9, 07745 Jena, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Popp
authors.affiliation: Aquatic Geomicrobiology, Friedrich Schiller University Jena, Dornburgerstr. 159, 07743 Jena, Germany; German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany. Electronic address: kirsten.kuesel@uni-jena.de.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Küsel
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D057219:Biofouling; D004269:DNA, Bacterial / Q000235:genetics; D005858:Germany; D064307:Microbiota; D008906:Mining; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D060986:Water Wells / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: Clogging; Gallionella; Iron oxidation; Microbial community; Microbial iron reduction potential