We describe a proteomic approach for identifying bacterial surface-exposed proteins quickly and reliably for their use as vaccine candidates. Whole cells are treated with proteases to selectively digest protruding proteins that are subsequently identified by mass spectrometry analysis of the released peptides. When applied to the sequenced M1_SF370 group A Streptococcus strain, 68 PSORT-predicted surface-associated proteins were identified, including most of the protective antigens described in the literature. The number of surface-exposed proteins varied from strain to strain, most likely as a consequence of different capsule content. The surface-exposed proteins of the highly virulent M23_DSM2071 strain included 17 proteins, 15 in common with M1_SF370. When 14 of the 17 proteins were expressed in E. coli and tested in the mouse for their capacity to confer protection against a lethal dose of M23_DSM2071, one new protective antigen (Spy0416) was identified. This strategy overcomes the difficulties so far encountered in surface protein characterization and has great potential in vaccine discovery.

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Chromium poisoning of solid oxide fuel cell cathodes is up to now considered as one major factor which limits lifetime and is responsible for degradation. Still unclear is to what extent chromium poisoning is responsible and what the basic degradation mechanism is. At Forschungszentrum Jülich, this ambiguity is being clarified in two ways: firstly the post-mortem analysis of cells operated within a stack and secondly by carrying out single cell tests with varied chromium releasing sources and operating conditions. This paper summarizes the results of approximately 60 single cell tests. The experiments were carried out with variation of operation time, current density applied and the chromium source. The cells were characterized for their degree of degradation, for their chromium content and change in microstructure. The results show that cells solely degrade strongly when current density was applied and a strong chromium source was present, and support an electrochemical interaction mechanism.

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