Archaeal Biofilms: Composition of Extracellular Polymeric Substances, Exopolysaccharide Synthesis and Secretion in Sulfolobus Acidocaldarius

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biofilms9-59 https://doi.org/10.5194/biofilms9-59 biofilms 9 conference © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.

Archaeal biofilms: Composition of extracellular polymeric substances, exopolysaccharide synthesis and secretion in Sulfolobus acidocaldarius

Laura Kuschmierz1, Martin Meyer2, Benjamin Meyer1, Sonja-Verena Albers3, Christopher Bräsen1, Jost Wingender4, Oliver J. Schmitz2, and Bettina Siebers1 1Molecular Enzyme Technology and Biochemistry (MEB), Environmental Microbiology and Biotechnology, University of Duisburg- Essen, 45141 Essen, Germany 2Applied Analytical Chemistry (AAC), University of Duisburg-Essen, 45141 Essen, Germany 3Molecular Biology of Archaea, Institute for Biology II, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany 4Aquatic Microbiology, Environmental Microbiology and Biotechnology, University of Duisburg-Essen, 45141 Essen, Germany

Archaea, representatives of the third domain of life, are often referred to as “extremophiles” since most of the cultivable species are adapted to extreme environments [1]. However, environmental cultivation-independent approaches (metagenomics) revealed a wide distribution of Archaea in moderate habitats suggesting a major role in geochemical processes. Similar to Bacteria, also Archaea are believed to exist predominantly in the biofilm mode, but knowledge about archaeal biofilm formation and structure, extracellular polymeric substance (EPS) composition and synthesis is scarce [2].

Sulfolobus acidocaldarius is a thermoacidophilic, aerobic Crenarchaeon (78°C and pH 2-3) that was isolated from acid hot springs [3]. The organism is easy to cultivate under laboratory conditions and a genetic system is established. In this study, we investigateS. acidocaldarius biofilms with a special focus on synthesis and transport of exopolysaccharides (PS). PS constitute a major EPS component beside proteins and eDNA, suggesting an important role in Sulfolobus biofilms, and changes in PS composition were observed in response to environmental stress [4]. A gene cluster encoding several glycosyltransferases (GTs) as well as membrane proteins (MPs), likely involved in exopolysaccharide synthesis, was identified inS. acidocaldarius. Several deletion mutants have been constructed lacking certain GT and MP encoding genes from the PS gene cluster. A combination of methods including the quantification of biofilm formation, isolation and quantification of EPS components, visualization of biofilm and PS structures via confocal laser scanning microscopy as well as molecular and biochemical techniques have been applied to compare biofilm characteristics of wildtype and mutant strains. First insight into the function of GTs and MPs will be presented and a model of PS synthesis and export will be proposed.

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[4] Jachlewski et al. (2015). Front. Bioeng. Biotechnol. 3, 123.