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The role of c-di-GMP in biofilm formation of the filamentous cyanobacterium Nostoc punctiforme
(2016)
The signaling molecule c-di-GMP is a ubiquitous second messenger in bacterial species including cyanobacteria. C-di-GMP stimulates the biosynthesis of extracellular polymeric substances (EPS) in biofilms and regulates the transition between a motile and a sessile life style in many bacteria. In our study we focus on c-di-GMP function and EPS production associated with biofilm Formation in Nostoc punctiforme, which is known to produce EPS in biofilms and liquid culture.
Genetic manipulation of protective pigments in a rock-inhabiting model fungus Knufia petricola A95
(2016)
Black ascomycetous microcolonial fungi are persistent inhabitants of rock surfaces, but are especially conspicuous in hostile environments like cold and hot deserts. The unique robustness of MFCs is supported by protective pigments, like melanin and carotenoids. We study the role of these pigments in the stress resistance of the model rock fungus Knufia petricola (Chaetothyriales) strain A95.
Several fires involving ETIC (external thermal insulation composite) systems with polystyrene foam insulation in Germany led to an extensive discussion about fire safety of such systems. A collection initiated by the Frankfurt fire service of façade fires which include polystyrene insulation foam shows that especially fires which started in front of the buildings led to more severe fires of the façade than fires that started inside the buildings. In several fires the ignition source were burning waste containers. Three large scale tests which were initiated by German building ministries showed weaknesses of the existing systems when challenged by a bigger fire source in front of the façade. Since then measures have been introduced to enhance these systems and an additional test with a 200 kg wood crib in front of a large test rig has been used for approval of ETICS. However, the recently introduced German draft standard DIN E 4102-20 does not take these changes into account although real cases and the large scale tests showed that fire scenarios with a bigger ignition source as a waste container are not covered by the DIN E 4102-20. Numerical investigations show that regarding the heat flux to the area above the opening (e.g. a window) also only a fraction of real fires is covered. Additionally damaged systems have been investigated using the Single Burning Item (SBI) test with higher heat release rates of the burner. The damage significantly influenced the fire development of the specimen. Collapse of a damaged coating of an ETIC system occurred during the test and had a sudden fire growth as a result as the whole specimen was suddenly on fire. Several effects which could be seen in the intermediate scale tests correspond to observations which were made in the real cases. In Germany insulation of existing buildings is often enhanced with application of ETICS. In most cases the buildings are in use at the time when the construction takes place. At several stages of the construction process large amounts of unprotected polystyrene are stored in immediate proximity of the building and unprotected polystyrene can be in place on the façade for several weeks. As a consequence of the investigations challenges and possible measures to enhance fire safety of ETIC systems are discussed.