4 Material und Umwelt
Filtern
Erscheinungsjahr
- 2019 (30) (entfernen)
Dokumenttyp
- Posterpräsentation (30) (entfernen)
Sprache
- Englisch (30)
Referierte Publikation
- nein (30)
Schlagworte
- Biocides (6)
- Antimicrobial resistance (5)
- Corrosion (3)
- Fertilzer (3)
- Horizontal gene transfer HGT (3)
- Knufia petricola (3)
- Microbiology (3)
- Resistance evolution (3)
- ATR (2)
- Bacteria (2)
Organisationseinheit der BAM
- 4 Material und Umwelt (30) (entfernen)
In this poster we will present some results of a research projects dealing with Arabic recipes of black inks [1-2]. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed.
We will show procedures and problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on squid ink [3] and mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect [4]. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol, the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts.
[1] A. Schopen, Tinten und Tuschen des arabisch-islamischen Mittelalters, Göttingen: Vandenhoeck & Ruprecht, 2004
[2] S. Fani, Le arti del libro secondo le fonti arabe originali. I ricettari arabi per la fabbricazione degli inchiostri (sec. IX-XIII): loro importanza per una corretta valutazione e conservazione del patrimonio manoscritto, PhD thesis, Napoli: Università L’Orientale, 2013
[3] S. Centeno, J. Shamir Journal of Molecular Structure, 873 (2008), 149-159
[4] C. Colini et. al, Manuscript cultures, 11 (2018) 43-50
In this poster we will present some results of a research projects dealing with Arabic recipes of black inks. To improve conservation practices of Arabic manuscripts we have assessed the feasibility of the recipes collected from many Arabic sources on bookmaking and reproduced the most common inks. Ink samples were then artificially aged and analysed using an array of analytical techniques, mostly non-invasive, in order to build a database of Arabic inks and their ingredients and also to verify the detection limits of the portable equipment employed.
First, we will provide an overview of the sources [1-2] employed in the study – dating from 9th to 14th century, although the manuscripts in which they can be found dates up to the 20th century – with an eye on the ink typologies (real and perceived by the compilers). Then we will show how, by reproducing the recipes, it was possible to shed light on some oddities in the procedures and the choice of ingredients. In the end we will discuss problems concerning the identification of ink types and ingredients using reflectography (in Vis, IR and UV), X-Ray Fluorescence, Infrared and Raman spectroscopy. The focus will be in particular on mixed inks – both in the form of carbon inks with the addition of tannins and of a mixture of carbon and iron gall inks – which are particularly difficult to detect [3]. We will also examine the results of iron gall inks made with iron filings or nails instead of vitriol and the various precursor used to extract gallic acid that are mentioned in the sources as surrogates of gall nuts.
[1] A. Schopen, Tinten und Tuschen des arabisch-islamischen Mittelalters, Göttingen: Vandenhoeck & Ruprecht, 2004
[2] S. Fani, Le arti del libro secondo le fonti arabe originali. I ricettari arabi per la fabbricazione degli inchiostri (sec. IX-XIII): loro importanza per una corretta valutazione e conservazione del patrimonio manoscritto, PhD thesis, Napoli: Università L’Orientale, 2013
[3] C. Colini et. al, Manuscript cultures, 11 (2018) 43-50
Black yeasts form a polyphyletic group of Ascomycota that colonize bare surfaces like rocks, facades of buildings, and solar panels. Their protective adaptations enable an adequate response to fluctuating and diverse temperature, water and UV radiation stresses. Together with bacteria and algae they form sub-aerial biofilms (SAB) this way discoloring and weathering the surfaces they grow on. Strain A95 of Knufia petricola (Eurotiomycetes, Chaetothyriales) displays both typical yeast-like cell growth and constitutive dihydroxynaphthalene (DHN) melanogenesis. Along with the cyanobacterium Nostoc punctiforme as photobiont, it is already used in a model system for studying SAB formation and bio-weathering. Applying the recently developed tools for the generation of deletion mutants will allow to define gene functions and to identify genes critical for abiotic and biotic interactions. We present a chromosome-level genome assembly and annotation for K. petricola A95. The genome was assembled with MaSuRCA using a hybrid assembly approach of Illumina MiSeq and PacBio SMRT sequencing data. The resulting assembly consists of 17 contigs including the complete mitochondrial genome and five complete chromosomes. It shows indication of repeat-induced point mutations (RIP). Supported by RNA sequencing data from eight different growth conditions, 10,994 genes were predicted with the BRAKER2 pipeline. Functional annotation of genes was obtained from general functional annotation databases and the fungal specific database FungiPath. Comparative analyses are in progress to identify genes specific to black yeasts, that may facilitate the survival on exposed surfaces. In sum, the genome sequence of K. petricola is a valuable resource to gain insight into the protein inventory and functional pathways of extremotolerant and symbiosis-capable fungi.
Black microcolonial fungi (MCF) are persistent inhabitants of rock surfaces in hostile desert environments. In these niches, MCF have evolved mineral-weathering and symbiotic capabilities as well as mechanisms to cope with multiple stresses such as solar irradiation, temperature extremes and low water activity. Due to their stress tolerance these ascomycetes are prominent in modern terrestrial ecosystems – like man-made material surfaces from roof to solar panels. MCF interactive capabilities support their facultative symbiotic relationships with cyanobacteria and ensure their rock-weathering geochemical activity.
Using the rock-inhabiting fungus K. petricola A95 (Chaetothyriales), we developed transformation protocols and deleted genes responsible for production of the protective pigments melanins and carotenoids. To confirm that the mutant phenotypes were not due to hidden mutations, melanin synthesis was restored by complementing the mutants with the respective wild type genes. Strains of K. petricola carrying gene variants for fluorescent proteins EGFP and DsRed are available. We successfully labelled the cytoplasm, nuclei, peroxisomes and mitochondria. Targeted and ectopic integrations result in stable transformants suitable for further phenotypical characterization. As K. petricola is a non-pathogenic fungus with all characteristic features of MCF, including meristematic growth, melanized cell-walls, extracellular polymeric substances and extensive pigment production, our results will shed light on protective role of pigments during cell wall maturation and oxidative stress defence in rock-inhabiting MCF. Genes involved in environmental sensing or substrate and phototroph interactions are currently targeted. With the help of a mutant collection and fluorescently labelled K. petricola we will be able to investigate interactions of MCF with environmental stressors, mineral substrates, soil matrices and phototrophic symbionts.
A Genetic Toolbox for Exploring the Life Style of the Rock-inhabiting Black Fungus Knufia petricola
(2019)
After their discovery on rock surfaces in cold and hot deserts, a polyphyletic group of ascomycetous black fungi was found to dominate a range of hostile environments – natural and man-made, from salterns to dishwashers, roofs and solar panels. Together with bacteria and algae they may establish sub-aerial biofilms and cause weathering of the surfaces they grow on. Their impressive survival abilities as well as their constitutive protective pigmentation and cluster-like microcolony organisation are similar in environmental isolates as well as in heat-tolerant opportunistic pathogens of animals and humans. The exact genetic properties that ensure their survival in extreme environments can be studied if some black fungi were amenable to genetic manipulations. We selected the rock-inhabiting fungus Knufia petricola (class Eurotiomycetes, order Chaetothyriales) that grows moderately in axenic culture and exhibits all the characteristics of black yeasts such as yeast-like cell growth, absence of reproductive structures and constitutive dihydroxynaphthalene (DHN) melanogenesis. For this environmental strain we developed protocols to efficiently generate and transform protoplasts resulting in stable homokaryotic transformants by targeting genes involved in pigment synthesis and expressing fluorescent reporter genes. Hence, endogenous and foreign genes can be expressed from episomal AMA1-containing plasmids and genome-integrated DNA constructs. Moderate rates of homologous recombination allow for both ectopic and targeted integrations. CRISPR-Cas9 was further validated as a strategy for obtaining selection marker-free mutants and silencing via RNA interference as an approach to study essential genes. Availability of this genetic toolbox and an annotated genome sequence is paving the way for studying interactions of K. petricola and other black yeasts with environmental stressors, material surfaces, soil matrices and phototrophic symbionts.
A mobile Bruker S2 Picofox TXRF spectrometer has been used in two field campaigns within the EMPIR env07 AEROMET project for the on-site analysis of cascade impactor aerosol samples.The results show that even at moderate air pollution levels – i.e.PM10 fairly below 20 μg/m³ - element mass concentrations in air in the range of 100 pg/m³could be measured in up to 13 size bins after sampling times of less than only 0.5 days.
The particle size distribution is considered the most relevant information for nanoscale property identification and material characterization. The current OECD test guideline on particle size and size distribution (TG 110) is not applicable to ‘nano-sized’ objects. In this project we thus develop a new OECD test guideline for the measurement of the size and size distribution of particles and fibers with at least one dimension in the nanoscale. A fiber is defined as an object having an aspect ratio of length/diameter l/d >3. The width and length of each fiber should be measured concurrently.
In order to measure the particle size distributions, many techniques are available. 9 methods for particles and 2 methods for fibres have been tested in a prevalidation study and appropriate methods will be compared in an interlaboratory round robin test starting in February 2019.
Microbiologically influenced corrosion is a multidisciplinary research area. To develop successful mitigation strategies, expertise from the industry and research institutes are essential. In Department 4.1, we developed an innovative laboratory flow model (Hi-Tension) that allows effective monitoring of MIC under both standard and non-standard conditions. The flow model allows flexibility with material selection, flow rates, temperature and other environmental parameters changes. Furthermore, the flow model allows integration of electrochemical measurements using microsensors, providing a comprehensive view of corrosion at the biofilm level. Currently, initial results indicate corrosion in the flow model is significantly higher than that of standard laboratory set ups, i.e. static incubations, particularly for methane-producing microorganisms.
Microbial modelling of sulfate-reducing bacteria (SRB) and methanogenic archaea (ME) using iron
(2019)
Sulfate reducing bacteria (SRB) and methanogenic archaea (MA) are commonly found in the oil and gas environments. The formation of hydrogen sulfide (HS-) is particularly concerning for the petroleum industry due to its corrosiveness. However, the activities of SRB are limited to the concentration of sulfate present in the environment, whereas methanogens can utilize substrates such as H¬2 for methanogenesis. MA is commonly found in sulfate-free environments, such as deep sediments, and are known to form interspecies electron transfer relationships with SRB. Recently, SRB and MA capable of microbiologically influenced corrosion (MIC) by using elemental iron as a direct electron source (EMIC) have gained increased attention. On the iron surface, EMIC-SRB can outcompete EMIC-MA in the presence of sulfate, but this changes as sulfate depletes. The formation of FeS on the metal surface can be further utilized by MA for methanogenesis as it provides a conductive path. However, the possible kinetics involved of the overall process are currently unknown.
We obtained a co-culture of EMIC-SRB and EMIC-MA to investigate the growth rates and electrical potential changes under different environmental conditions, including changes in pH, temperature and salinity. Results indicate that under neutral conditions and using iron as the sole substrate, methane production (up to 5 mM) starts after sulfate was depleted. Electrochemical measurements will be conducted on the co-culture under different conditions to determine the changes in the electrical potential in correlation with the sulfate and methane concentration. Fluorescence and electron microscope images of the biofilm structure will be used to visualize cell distribution and morphology. This study embarks the first step of understanding the relationship between EMIC-SRB and EMIC-MA. Such knowledge is important for the field of microbial electrophysiology and can be further explored for industrial applications.