Fakultät für Chemie - Former
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Personal data for Mark Schreiber

  Mark Schreiber
Mark Schreiber
PhD student
Room: F2-231
Phone: 0521 106 2152

The cellulase-subproteome in digesters - from grass to biogas

Common energy sources like crude oil or natural gas are not exhaustless. Furthermore, these energy carriers are responsible for the greenhouse effect whose consequences can already be noticed. Taking this into consideration the only alternative is to develop new nonpolluting energy sources to meet the growing energy demand. Digesters could be one answer to this problem.

Substrates for digesters should be easily available on the one hand and easily cultivable on the other. Additionally, potential food crops like corn etc. should be avoided as substrates. For this reason grass is in the focus.

Fig.1: Fermentation cycle.

As grass mainly consists of cellulose the challenge is to make cellulose available as an efficient feedstock for digesters. Bacterial cellulases (β-glucosidases) digest cellulose into its monomer glucose. This hydrolysis is the key step to enter the fermentation process (fig.1).
In this case the analysis of the cellulase-subproteome (and if applicable the ligninase-subproteome) is of vital importance for the optimization of the biogas production process.
The proteome of complex bacteria communities easily includes more than 1000 proteins which can be expressed in varying ratios. For analytical reasons it is indispensable to reduce the proteome to the relevant proteins and to enrich low expressed proteins.
The research group Sewald developed efficient methods for functional proteomics in the past. First, specific ligands/inhibitors with a high affinity to the target proteins are synthesized and subsequently immobilized through suitable linkers on a surface or on polymer beads.
Azoles with Ki-values up to the nanomolar scale are known as effective β-glucosidase inhibitors (fig.2).

Fig.2: Different known β-glucosidase inhibitors.

Immobilization of these inhibitors provides the possibility to bind and enrich selectively β-glucosidases out of a complex mixture of enzymes. The isolated β-glucosidases can be characterized and identified with 2D-PAGE followed by MS-fingerprint analysis (fig.3).

Fig.3: Affinity chromatography for a selective binding and enrichment of proteins.

The knowledge of the β-glucosidase spectrum with dependence on various parameters of the digester affords an optimization of the cellulase activity. This also means an optimization of the whole fermentation process, leading to an optimized energy output.

Diploma thesis

Biochemische Modifizierung des Transkriptionsfaktors PhoB und deren Auswirkungen auf die Aktivität, Universität Bielefeld, 2007


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[2] F. Vincent, T. Gloster, J. Mcdonald, C. Morland, R. Stick, F. Dias, J. Prates, C. Fontes, H. Gilbert, G. Davies, CHEMBIOCHEM, 2004, 5, 1596

[3] S. Vonhoff, T. Heightman, A. Vasella, Helvetica Chimica Akta, 1998, 81, 1710