Metal interaction processes with cell wall components of Gram-positive bacteria studied by QCM-D


Metal interaction processes with cell wall components of Gram-positive bacteria studied by QCM-D

Suhr, M.; Matys, S.; Raff, J.; Pollmann, K.

Bacterial isolates from the uranium mining waste pile Haberland (Johanngeorgenstadt, Saxony) possess high affinities for heavy metals [1]. Binding sites are predominantly provided by the components of the bacterial cell wall, mainly by surface layer proteins, but also from other parts of the cell wall e.g. membrane lipids.

A deeper understanding of the metal interaction with the biosphere is important not only from an ecological point of view but also from an application oriented one.
Parts of our investigations focused on surface layer proteins (S-layers). They represent the outermost cell envelope of many eubacteria and archaea forming highly ordered paracrystalline lattices not only on the living cell, but also after isolation on various technical surfaces by self-assembling processes [2]. Such biological structures can be used e.g. as filter materials for waste water treatment and as templates for synthesis of bio-based sensory layer or chemical catalysts [3]. Nevertheless, the investigation of interactions of the cell wall components like S-layer, peptidoglycan, lipids and secondary cell wall polymers (SCWP) with metals and nanoparticles both as molecules and as intact layers on a molecular level remains challenging.

In addition, to standard bio-analytical methods the quartz crystal microbalance with dissipation monitoring (QCM-D) represents a versatile tool to track and control the biological layer formation, metal interaction and nanoparticle deposition as well as adsorption kinetics. This method allows the real time detection of sorption processes on a molecular level and gives further information of the viscoelasticity [4].

Aim of our study was the investigation of layer adsorption of isolated cell wall components on technical surfaces such as glass or silicon using a simplified model derived from Gram-positive bacteria in order to get basic information about multilevel processes in complex natural systems. The sorption behavior of metals with these components will be investigated by QCM-D. The results were evaluated by supporting atomic force microscopy (AFM).

[1] J. Raff et al. (2003), Chem. Mater. 15, 240-244.
[2] Sleytr, U. B. et al. (2007), FEMS Microbiology Letters 267(2), 131-144.
[3] K. Pollmann et al. (2006), Biotechnol. Adv. 24, 58– 68.
[4] A. E. Lopez et al. (2010), Small 6 (3), 396 -403.

Keywords: Bacteria; QCM-D; Biosorption; sorption; heavy metal; metal binding; AFM; cell wall

  • Lecture (Conference)
    Annual Conference of the Association for General and Applied Microbiology (VAAM), 10.-13.03.2013, Bremen, Deutschland

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