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Front. Microbiol. | doi: 10.3389/fmicb.2019.00896

Insight into interactions of thermoacidophilic archaea with elemental sulfur: biofilm dynamics and EPS analysis

  • 1Geomicrobiology Unit, Federal Institute For Geosciences and Natural Resources, Germany
  • 2Department of River Ecology, Helmholtz-Zentrum für Umweltforschung (UFZ), Germany
  • 3Guangzhou University, China
  • 4Charité Medical University of Berlin, Germany
  • 5University of Duisburg-Essen, Germany

Biooxidation of reduced inorganic sulfur compounds (RISCs) by thermoacidophiles is of particular interest for the biomining industry and for environmental issues, e.g. formation of acid mine drainage (AMD). Up to now, interfacial interactions of acidophiles with elemental sulfur as well as the mechanism of sulfur oxidation by acidophiles, especially thermoacidophiles, are not yet fully clear. This work focused on how a crenarchaeal isolate Acidianus sp. DSM 29099 interacts with elemental sulfur. Analysis by Confocal laser scanning microscopy (CLSM) and Atomic force microscopy (AFM) in combination with Epifluorescence microscopy (EFM) shows that biofilms on elemental sulfur are characterized by single colonies and a monolayer in first stage and later on 3-D structures with a diameter of up to 100 micrometers. The analysis of extracellular polymeric substrances (EPS) by non-destructive lectin approach (fluorescence lectin-barcoding and analysis) using several fluorochromes shows that intial attachment was featured by footprints rich in biofilm cells were embeded in a EPS matrix consists various of glycoconjugates. Wet chemistry data indicate that carbohydrates, proteins, lipids and uronic acids are the main components. Attenuated reflectance (ATR)-Fourier transformation infrared spectroscopy (FTIR) and high-performance anion exchange chromatography with pulsed amperometric detection (HPAE-PAD) indicate glucose and mannose as the main monosaccharides in EPS polysaccharides. EPS composition as well as sugar types in EPS varies according to substrate (sulfur or tetrathionate) and lifestyle (biofilms and planktonic cells). This study provides information of the building blocks/make up as well as dynamics of the thermoacidophilic archaeon biofilms in extremely acidic environments.

Keywords: Attachment, Sulfur oxidation, EPS (extracellular polymeric substance), thermophilic archaea, CLSM (confocal laser scanning microscopy), Biofilms

Received: 24 Nov 2018; Accepted: 08 Apr 2019.

Edited by:

Alexander Loy, University of Vienna, Austria

Reviewed by:

Arnulf Kletzin, Darmstadt University of Technology, Germany
Cassandra Marnocha, Niagara University, United States  

Copyright: © 2019 Zhang, Neu, Li, Blanchard, Zhang and Sand. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Mr. Ruiyong Zhang, Federal Institute For Geosciences and Natural Resources, Geomicrobiology Unit, Hanover, Lower Saxony, Germany, ruiyong.zhang@bgr.de
Prof. Wolfgang Sand, University of Duisburg-Essen, Duisburg, 47057, North Rhine-Westphalia, Germany, wolfgang.sand@uni-due.de