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Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in offshore industries, such as the oil and gas pipelines, due to the high concentrations of sulfate in the seawater. SRM act upon the metal by the reactiveness of hydrogen sulfide (HS-), and by withdrawal of the available electrons (Fe --> Fe2+ + 2e-; E° = -0.47 V) in electrical contact with the metal (EMIC). However, methanogenic archaea can also cause MIC. Because they do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of methanogens, we studied the EMIC methanogenic strains isolated from marine sediments (Methanobacterium-affiliated strain IM1) and crude oil tanks (Methanococcus maripaludis Mic1c10), in an in-house developed flow-through cell to simulate a fluctuating environment. A co-culture of M. maripaludis and D. alaskensis was also established to study the effect of syntrophic growth on metal corrosion that may occur in industrial pipelines. Results indicate that the rates of iron corrosion due to coupled methanogenesis (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr). Surface analyses of the metal showed severe pitting with high methane production. Genomic analysis of the EMIC methanogen M. maripaludis Mic1c10 will provide an insight on the mechanisms of MIC. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC
Seit einigen Jahren wird in den Medien viel über das Thema Mikroplastik (MP) diskutiert. Dabei wird häufig von einer großen Anzahl an MP-Partikeln in allen Bereichen der Umwelt, wie dem Wasser, dem Boden, der Luft und in Biota sowie über mögliche Gefahren ausgehend von MP, berichtet. Jedoch sind diese Studien häufig nicht untereinander vergleichbar, da verschiedene Konzepte der Probennahme, der Aufbereitung und unterschiedliche Detektionsverfahren verwendet werden. Um diesen Mangel an vergleichbaren und aussagekräftigen Daten zu beheben, wird aktuell versucht, eine Harmonisierung der Mikroplastikanalytik voranzutreiben. Neue, schnellere Methoden zur MP Quantifizierung wurden entwickelt. Gleichzeitig werden neue Strategien zur Probenahme und Probenvorbereitung konzipiert, da hier die Fehlerquellen besonders große Auswirkungen auf das Ergebnis haben.
In diesem Vortrag werden verschiedene Verfahren bezogen auf Probennahme, -vorbereitung und Analytik gezeigt und bezüglich ihres möglichen Ergebnisses diskutiert.
Spectral encoding of cells or particles and the discrimination of multiple spectral codes are a critical process in flow cytometry (FCM). Typical issues in spectral encoding are, e.g., the spectral overlap of codes, or the increasing complexity of instruments . The exploitation of the photoluminescence lifetime (LT) as an encoding parameter could be used to circumvent both of these issues, as it adds another dimension to the parameter space, or, when used as a stand-alone parameter, requiring only one excitation light source and one detector. While LT encoding was considered already decades ago it is still not implemented as a routine technique in FCM yet, mainly due to the challenge of very few photons being available within the limited transition time of a cell or particle through the laser spot.
Recently, we demonstrated LT-FCM based on luminophores with ns LTs in a compact and low-cost flow cytometer. Measurements on polymer microbeads containing luminophores with distinctly different excited state LTs enabled the complete discrimination of three LT codes and five codes in total could be identified.
Now, we have extended our approach towards considerably longer LTs by custom-made polymer microbeads loaded with different ratios of InP/ZnS and AgInS2 quantum dots. The use of these materials significantly expands the usable time range for LT encoding to up to several hundred ns. Our studies demonstrate the possibility to further increase the number of viable LT codes for multiplexing in LT-FCM without the need for extensive hardware modifications.
The comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters require accurate and quantitative photo-luminescence measurements. This is of special importance for all photoluminescence applications in the life and material sciences and nanobiophotonics. In the following, procedures for the determination of the spectroscopic key parameter photoluminescence quantum yield, i.e., the number of emitted per absorbed photons, in the UV/vis/NIR/SWIR are presented including pitfalls and achievable uncertainties and material-specific effects related to certain emitter classes are addressed.
Luminescent nanocrystals like core/shell semiconductor quantum dots and lanthanide doped nanophosphors as well as gold nanoclusters with emission in the visible (vis) and particularly in the near infrared (NIR) and short wavelength infrared (SWIR) region have been increasingly used as reporters in the life sciences and for bioimaging studies in the last years. This has led to sophisticated core-shell particle architectures of different chemical composition utilizing semiconductor quantum dots and lanthanide-based nanocrystals and initiated the design of gold nanoclusters with different ligands. In addition, this led to an increasing number of quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield to identify optimum particle structures. In the following, an overview of different classes of nanocrystalline emitters and their photophysics is provided and examples for the absolute characterization of the photoluminescence properties of these different vis/NIR/SWIR emitters are shown including excitation power density-dependent studies on the ensemble and single particle level. Also, the impact of such measurements on a profound mechanistic understanding of the underlying nonradiative deactivation pathways is highlighted as required for reporter design.
Moderne Vitrinen sollen gleichzeitig eine hohe Dichtigkeit und die Abwesenheit jeglicher Fremdstoffe in den Vitrinen gewährleisten. Diese Anforderungen sind zeitgleich kaum erfüllbar, da es emissionsfreie Materialien (vor allem Kleb- und Beschichtungsstoffe) nicht gibt. Um die potentiellen Emissionen zu minimieren wurde ein Messverfahren entwickelt, welches inzwischen als BEMMA-Schema (Bewertung von Emissionen aus Materialien für Museumsausstattungen) in die Museumswelt Einzug genommen hat.
Die erfolgreiche Bewertung der für den Bau verwendeten Materialien gemäß BEMMA-Schema resultiert nicht in einer emissionsfreien Vitrine, sondern soll bei der Auswahl geeigneter Materialien zur Herstellung möglichst emissionsarmer Vitrinen helfen. Konkrete handwerkliche Durchführungen beim Bau, Dichtheits-anforderungen, wie auch die Aufstellbedingungen (Umgebung der Vitrine) beeinflussen die Emissionscharakteristik der fertigen Vitrine in der Praxis. Eine saubere Vitrine hilft nichts in einer belasteten Umgebung oder auch bei emittierenden Exponaten. Inzwischen liegen Erfahrungen mit dem Schema seit 2012 vor.
Der Messablauf sieht vor, dass von den Materialien kleine Muster mit der Mikrokammer (Markes) innerhalb von 2 Tagen untersucht werden. Dabei wird mit Silikagelkartuschen auf Ameisen- und Essigsäure, mit DNPH auf Aldehyde und Ketone und mit Tenax® sowohl auf VOC als auch für die spezifische Oxim-Analytik die Abluft der Mikrokammern untersucht. Die Bewertungskriterien basieren auf den Ergebnissen einer Vorstudie mit ca. 150 verschiedenen Produkten im Zeitraum 2010 bis 2012.
Vor nun 30 Jahren, im Jahre 1989, wurde die erste Zulassung für eine Kunststoffdichtungsbahn (KDB) von der BAM auf der Grundlage des „Niedersächsischen Dichtungserlasses“ erteilt. Vor ungefähr 10 Jahren wurde die BAM mit dem Erscheinen der Deponieverordnung (DepV) mit der Zulassung von Geokunststoffen, Polymeren und Dichtungskontrollsystemen beauftragt. Wir möchten dies zum Anlass nehmen, an dieser Stelle den viele ehrenamtlichen Experten des Fachbeirats und seiner Arbeitsgruppen für ihren Einsatz und die Unterstützung zu danken.
Darüber hinaus soll über aktuelle Arbeitsthemen und Entwicklungen im Fachbeirat berichtet werden. So wurde in einer Sondersitzung des Fachbeirats über die Entlassung aus der Nachsorgephase beim Einsatz von Geokunststoffprodukten in Böschungen diskutiert. Die Unterarbeitsgruppe Fremdüberwachung in der Produktion hat getagt. Darüber hinaus werden Änderungen in den Zulassungsrichtlinien für Kunststoffdichtungsbahnen, Kunststoff-Dränelemente und Geogitter kurz vorgestellt.
Ein Ringversuch ist eine Methode der externen Qualitätssicherung für sowohl Messverfahren als auch die Eignung von Mess- und Prüflaboratorien. Dabei werden möglichst identische Proben mit identischen Verfahren oder mit unterschiedlichen Verfahren untersucht. Die Teilnahme an Ringversuchen ist für alle akkreditierten Laboratorien ein wesentlicher Baustein der institutsinternen und -externen Qualitätssicherung. Je mehr Faktoren Einfluss auf das Endergebnis haben können, desto wichtiger ist es diese Faktoren zu kennen und deren Einflüsse durch weitestgehende Vergleichbarkeit der Messverfahren zu minimieren.
Für die Bewertung von Emissionen aus Bauprodukten haben sich Emissionsmess-kammer-Untersuchungen als Messverfahren etabliert. Um den Geruch auch für Innenraumanwendungen bewertbar zu machen sind in den letzten Jahren erste Normen entstanden (z. B. DIN ISO 16000-28 und VDI 4302-1). Um die Eignung dieser Normen und deren Anwendung zu untersuchen sind seit 2012 nunmehr 3 Ringversuche der BAM auch zum Thema Geruch durchgeführt worden.
Die bislang durchgeführten Ringversuche mit dem Ziel der Geruchsbewertung wiesen Standardabweichungen von ca. 24 bis 30 % um den jeweiligen Mittelwert auf und wiesen somit ähnliche Werte auf, die auch bei den VOC-Vergleichen ermittelt wurden. Diese Entwicklungen werden hier aufgezeigt.
Whilst the concept of ecodesign is intended to account for the environmental impacts of the product across its whole lifecycle, European ecodesign policy to date has been heavily focused upon energy efficiency in the use phase. The Ecodesign Directive and Energy Labelling Regulation have achieved substantial energy savings since their inception. For many products, the magnitude of savings available from further tightening existing energy efficiency requirements is now often outweighed by savings that can be achieved by material efficiency requirements. Further, there are some products such as smartphones for which there are limited gains to be made in energy efficiency but for material efficiency. In the Commission’s Circular Economy Action Plan from 2015, a new direction was defined for ecodesign policy, to systematically examine considerations such as reparability, durability, upgradability, recyclability, or the identification of certain materials or substances. The Commission consequently issued a standardisation request (M/543, 2015) to the European Standardization Organisations (CEN / CENELEC / ETSI) to develop generic/horizontal standards relevant to energy-related products that address these major aspects of material efficiency. In this study we evaluate the potential contribution of these new standards (with specific focus on the standards for repair, durability and recyclability) to future developments under the European Ecodesign Directive. Opportunities for the impact of these standards to be enhanced by future work are highlighted.
Nanomaterials are present in our everyday life. Paint coats, sunscreens, catalysts and additives for tyres are good examples for the use of such materials in mass-market products. The problem of the safety of nanomaterials is recognized as a problem for health and environment, which lead to the special registration of nanomaterials according to an annex of REACH as of 2020. But a great problem for the risk assessment of nanomaterials that several factors could influence the hazardous nature of them. Additional to composition, crystal structure, size and shape the surface properties of such particles belong to these parameters for risk assesment. The reason for the relevance of the surface is obvious: the smaller the particle, the higher is the share of the surface. Additionally, the surface is the region of the particle which interacts with the surrounding which is another crucial factor for the understanding the effect of a nanomaterial on health and environment. In the OECD Testing Programme on Manufactured Nanomaterials exists consequently an Endpoint 4.30 Surface Chemistry in Chapter 4. PHYSICAL AND CHEMICAL PROPERTIES. In summary, there is obviously a need for a correlation between surface chemical analytic data and toxicity. To fill in this gap, we present surface analytic results obtained with X-ray photoelectron spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry and correlate them with cytotoxic data gain by high-throughput screening experiments. It must be noted, that these experiments were done at the same set of titania materials taken from the JRC (Joint Research Centre of the European Union) Nanomaterials Repository. As material TiO2 was chosen due to its widespread use in consumer products, e.g. paint coats and sunscreens. With this new approach a better understanding of the influence of surface properties on the toxicity can be expected leading to a better risk assessment of these materials.
A fundamental question in ecology is how biodiversity affects ecosystem function. Biodiversity is commonly estimated based on genetic variation. We investigated a new approach that defines and measures biodiversity in complex microbial communities. We used the variation in multiple functionally-relevant, phenotypic traits measured in parallel in single cells as a metric for microbial phenotypic diversity. We studied phenotypic diversity and ecosystem functioning throughout different photosynthetic layers dominated by divergent microbial communities in the gradient of Lago di Cadagno. We determined genetic diversity by 16S and 18S amplicon sequencing and bulk ecosystem functioning (photosynthesis). In addition, we determined phenotypic diversity using single-cell technologies such as nanometer-scale secondary ion mass spectrometry (NanoSIMS) correlated with confocal laser scanning microscopy (CLSM) and scanning flow-cytometry. We measured functional trait variation between individuals in 13CO2 fixation, 15NH4+ uptake, and variation in physio-morphological cell traits, such as cell size, shape, and auto-fluorescence for various pigments related to photosynthesis. We used the distances between individuals in a multidimensional trait space to derive phenotypic trait-based diversity indices, such as trait richness, trait evenness, and trait divergence. We find that phenotypic trait divergence associates with ecosystem functioning, whereas genetic diversity does not. Including activity-based, single-cell phenotypic measurements with NanoSIMS provided an additional accuracy to the trait-based diversity assessment and allowed us to formulate hypotheses on the mechanisms that shape the correlation between phenotypic diversity and eco-system function. Together, our results show that phenotypic diversity is a meaningful concept to measure microbial biodiversity and associate it with ecosystem functioning.
The number of publications reporting the amount of microplastic (MP) all over the world increased rapidly. Methods used so far are very time consuming and not able to provide information on total contents. As harmonised sampling, sample preparation and analysis strategies are missing different studies can hardly be compared and quantitative data, including identification and mass contents of the polymers found, are missing. This leads to a lack of comprehensive understanding of MP occurrence, source and entry pathways into the environment.
We developed a method, Thermal Extraction/Desorption-Gaschromatography-Massspectrometry, as a fast screening method for MP analysis. Solid residues of water samples are heated up to 600 C under a N2 atmosphere without any sample preparation. The collected decomposition gases are separated in a gas chromatography system and detected in a mass spectrometer. Mass contents of the identified polymers can be calculated.
In this presentation we will show first results from the influent of the wastewater treatment plant Kaiserslautern (Germany) and its combined sewage system as possibly entry pathway. In order to determine the relevance of wastewater split streams analysis of grey water will be conducted. Samples are fractionally filtered by a sieve cascade with mesh sizes of 500, 100, 50 µm.
Uninvited and Welcomed Guests in Museums – Biological management of
clothes moths and woodworms
(2019)
In museums and historic houses clothes, moths (Tineola bisselliella, Tinea pellionella) and the furniture beetle (Anobium punctatum) are the most economically important pests on textiles or wooden artifacts, respectively. Their management is essential to protect cultural ethnological heritage and natural history collections for future generations.
Pest management strategies have changed over time. Today, intensive knowledge on pest biology and overall material science are key cornerstones in IPM concepts - also for the museum environment. The important first steps for sustainable pest management are risk assessment, early pest detection and identification of pathways of infestation. These steps are followed by physical and biological means of control, which have lately gained more importance than applying biocides.
Several potentially effective biological enemies of clothes moths and woodworm have been known for a long time, but their promotion for pest control in museums and historic houses is just beginning.
This short review summarizes current concepts of pest life cycle interruption by applying good quarantine and very specific biological measures. The lessons learned from recent faunistic surveys, life-history studies as well as behavioral observations of parasitoids and predators of clothes moths and woodworm may supplement the pest management tool box. The need for further research in this field is addressed.
The compatible solute ectoine is a versatile protectant synthesized by many prokaryotes. It is used as an osmolyte helping microorganisms to maintain an osmotic equilibrium. In addition, ectoine acts as a stabilizer and protects proteins, membranes and whole cells against detrimental effects such as freezing and thawing, drying and high temperatures. Its protective effect is explained by the preferential exclusion model, which postulates that ectoine does not directly interact with biomolecules but is excluded from their surface. Interestingly, details on the interaction of ectoine with DNA are still unknown. Therefore, we studied the influence of ectoine on DNA and the mechanisms by which ectoine protects DNA against ionizing radiation. To emulate biological conditions, we used a sample holder comprising a silicon chip with a Si3N4 membrane, which allows for electron irradiation of DNA in aqueous solution. Analysis by atomic force microscopy revealed that without ectoine, DNA was damaged by irradiation with a dose of 1,7 +/-0,3 Gy. With ectoine, DNA remained undamaged, even after irradiation with 15 Gy. Simulations with dsDNA and ectoine in water revealed a preferential binding of the zwitterionic ectoine to the negatively charged DNA. According to the simulations, binding of ectoine will destabilize dsDNA. Destabilizing is probably caused by the transition of B-DNA to A-DNA and will reduce the DNA melting temperature, which was experimentally proven. The preferential binding provides a stable ectoine shell around DNA, which allows ectoine to reduce OH-radicals and electrons near the DNA and thereby mitigating the damaging effect of ionizing radiation.
The rational synthesis and use of nanomaterials require the characterization of many different properties, ranging from particle size and size distribution over surface chemistry to more applicationrelevant features like optical, electrochemical, and magnetic properties. In the following, several methods for the characterization of functional groups on nanomaterials, like polymer and silica nanoparticles, semiconductor quantum dots, and lanthanide-based upconversion nanocrystals are presented. Additionally, procedures for the measurement of the key spectroscopic performance parameters of nanomaterials with linear and nonlinear photoluminescence, such as the photoluminescence quantum yield, are presented for the UV/vis/NIR/SWIR.
Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in oil and gas facilities. SRM act upon the metal by the re-activeness of hydrogen sulfide (HS-), and by withdrawal of the available electrons in electrical contact with the metal (EMIC). Methanogenic archaea (MA) can also cause MIC (Mi-MIC). Several MAs were identified to be corrosive by using elemental iron as the sole electron donor for methanogenesis, including Methanobacterium-affliated IM1 and Methanococcus maripaludis Mic1c10. Currently, low corrosion rates were reported for MA, possibly due to the formation of siderite (4Fe + 5HCO3- + 5H+ ® 4FeCO3 + CH4 + 3H2O). Since MA do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of MA, we studied the EMIC methanogenic strains (IM1 and Mic1c10) individually or part of a syntrophic co-culture with SRM. Corrosion studies were conducted using an in-house developed flow-through system to simulate fluctuating environmental conditions. Results indicate that the rates of iron corrosion by MA (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr) and the co-culture (0.1 mm/yr). Scanning electron microscopy (SEM) images of the metal incubated with MA showed severe pitting corrosion. Genomic analysis of the EMIC MA was conducted to provide an insight on the possible cellular mechanisms that could be involved. Furthermore, low concentrations of MA-targeting biocides will be applied to EMIC MA in static and flow conditions to gain insights for possible mitigation strategies. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC.
Plastics and rubber are used in many applications, such as packaging, building, construction and mobility. Due to their favourable properties like light weight, flexible processing and low costs their production and consequently their input into the environment has increased significantly over the last decades. In the environment, oxidation processes and mechanical abrasion lead to the decomposition of these plastics into small fragments, called microplastic (< 5 mm). By definition, microplastics only involve thermoplastics and duroplastics but elastomers made out of synthetic polymers (e. g. styrene butadiene rubber), modified natural polymers (e. g. natural rubber) and products of synthetic polymers (e. g. tires) are also part of the current microplastic discussion. The main entry pathway of rubber into the environment is the wear of used tire treads in road traffic. Lassen et al. showed that 60 % of the microplastic emissions in Denmark into the environment come from secondary microplastics generated by tires. Rain events can cause microplastic and rubber to get from the street into the street inlets. Depending on the sewage system, these waters are sometimes not cleaned in the sewage treatment plants and reach the surface waters untreated.
To analyse microplastic particles in samples, mainly FTIR or Raman spectroscopic methods are applied at present. Rubber or tire particles in environmental samples cannot be analysed by these methods, because the added carbon black leads to annoying absorption and fluorescent effects.
We developed a thermoanalytical method, the so-called TED-GC-MS (thermal extraction desorption gas chromatography mass spectrometry), which allows the simultaneous detection of microplastic and tire wear with almost no sample preparation in about 2.5 h. The TED-GC-MS is a two-step analytical method which consists of a thermobalance and a GC-MS system. Up to 50 mg of an environmental sample is heated up to 600 °C in a nitrogen atmosphere. During pyrolysis, between 300 and 600 °C polymer-specific decomposition products are produced and collected on a solid phase. Afterwards the substances are desorbed, separated and analysed using the GC-MS.
The aim of the present work is to present the TED-GC-MS as a time efficient screening method to quantify the industrial most relevant polymers in street run-off samples. Analytical challenges in the determination of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyamide (PA), polymethyl methacrylate (PMMA) and styrene-butadiene-rubber (SBR) as a component of tire wear are honestly discussed.
The study area is a 200 m long section of the Clayallee in Berlin, a representative typical urban catchment area. The road run-off in this section flows through the gullies directly into a sample chamber, which directs the runoff in an open channel to the rainwater sewer of this area. The sample chamber allows a sample to be taken directly from the road run-off without mixing with the run-off from other areas. The sample chamber is equipped with an automatic sampler. The automatic sampler is controlled by a conductivity sensor to detect the storm event at an early stage. The sensor gives the sampler a signal to start the sampling program when it gets in contact with water and reaches a certain conductivity threshold. The capacity of the sample container is 100 l and the maximum delivery of the automatic sampler is 2.8 l/min.
Afterwards, the water was pumped through various stainless-steel sieves with a diameter of approximately 20 cm and mesh widths of 500, 100, 50 μm. The obtained solids were steam sterilized, freeze-dried and measured with the TED-GC-MS.
The results of the TED-GC-MS-measurements are summarized in Figure 1. It shows the polymers which were detected in 1 mg of the dry masses of various street run off samples obtained during a period of 1.5 years. We detected PMMA, PS, PP, PE and SBR, as a component of tire wear in the samples. The quantification of the polymers leads to amounts of PS, PP, PE and SBR between 0 µg and 10 µg. PMMA was only detected in traces.
What isotopes can do...
(2019)
Der Vortrag beschäftigt sich mit den gängisten Methoden zur Probennahme, -vorbereitung und Detektion von Mikroplastik. Das Zusammenspiel von Fragestellung und Methode wird betont. Es wird auf das Dikussionspapier Analytik des BMBF-Forschungsschwerpunktes Plastik in der Umwelt besonders hingewiesen sowie Bemühungen zur Normierung der Methoden auf deutscher und internationaler Ebene dargestellt.
Sunlight, the major source of energy, drives life but in excess it provokes UV-induced DNA damage, accumulation of reactive oxygen species, desiccation, osmotic stresses and so on. Biological strategies to survive excess light include protection, avoidance and active utilisation. Phototrophic organisms including cyanobacteria, green algae and plants use all three strategies. Fungi occupying phototrophic niches may profit from the surplus photosynthetic products which also obliges them to cope with the same light-induced stresses. One way of handling these stresses would be to use similar signalling pathways to sense the presence and to interact with their phototrophic partners. Obviously, the levels of adaptation and responses to light will depend on the environment as well as fungal genotype and phylogenetic position. Black fungi – a polyphyletic group – accumulate the dark pigment DHN melanin in their cell walls and often occupy light-flooded habitats from phyllosphere to rock surfaces. Here we compare two sequenced melanised fungi of different lifestyles in their response to light.
The Leotiomycete Botrytis cinerea is an aggressive pathogen that primarily infects the above-ground parts of plants. It possesses large numbers of photoreceptors that respond to a broad spectrum of light. As a consequence, light controls morphogenesis in which it induces conidiation for disease spreading and represses sclerotial development for survival and/or sexual recombination. Cellular components involved in photo-perception and regulation of morphogenesis, stress responses and virulence have been identified and appear to regulate propagation, survival and infection. These include phytochromes, a group of photoreceptors which are particularly enriched in the Leotiomycetes and that mediate coordinated responses to light and elevated temperatures. Assuming that photo-regulation may be equally important for fungi that live in mutualistic relationships with phototrophs either by forming composite organisms or biofilms, we investigate the role of light in the rock-inhabiting Eurotiomycete Knufia petricola. Like other black yeasts, K. petricola grows slowly, does not form specialised reproductive structures and constitutively produces DHN melanin as well as carotenoids. Combining K. petricola with the cyanobacterium Nostoc punctiforme, we developed a model system for studying biofilm formation and bio-weathering. A genetic toolbox to manipulate this model system is being developed. K. petricola strain A95 possesses ten putative photoreceptors, more than found in filamentous Eurotiomycetes suggesting that light plays an important role for abiotic and biotic interactions in extremo-tolerant and symbiosis-capable fungi.