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153 Publications visible to you, out of a total of 153
Raman spectroscopic monitoring of the growth of pigmented and non-pigmented mycobacteria

Abstract (Expand)

Raman microspectroscopy has increased in popularity in the field of microbiology because it allows a spectral fingerprinting of bacterial pathogens at an unrivaled speed, which is important for the … early treatment of infectious diseases such as tuberculosis. An indispensable prerequisite for the success of this method is a profound knowledge, how the spectral profiles depend on the age of the bacteria. We therefore followed the growth of two rapidly growing Mycobacterium tuberculosis relatives, the pigmented Mycobacteriumaurum, and the non-pigmented Mycobacteriumsmegmatis, by means of Raman microspectroscopy. Both species showed remarkable temporal changes in the single-bacteria Raman spectra: In the signatures of M.aurum, pigment-associated Raman signals could be detected not until 72 h of growth and also remained highly variable thereafter. The Raman spectra of M.smegmatis exhibited lipid signals presumably arising from mycolic acids, which are a hallmark feature of mycobacteria, but only after the bacteria reached the late stationary growth phase (>48 h). A principal component analysis thus classified the Raman spectra according to the cultivation age. In summary, these findings have to be reckoned with in future studies dealing with the identification of mycobacteria via Raman microspectroscopy. Graphical abstract Changes in the chemical composition of bacterial cells over growth time may influence the results of Raman spectroscopic studies of bacteria.

Authors: S. Stockel, A. S. Stanca, J. Helbig, ,

Date Published: 21st Sep 2015

Publication Type: Not specified

Raman spectroscopy towards clinical application: drug monitoring and pathogen identification

Abstract (Expand)

Raman spectroscopy is a label-free method that measures quickly and contactlessly, providing detailed information from the sample, and has proved to be an ideal tool for medical and life science research. … In this review, recent advances of the technique towards drug monitoring and pathogen identification by the Jena Research Groups are reviewed. Surface-enhanced Raman spectroscopy (SERS) and ultraviolet resonance Raman spectroscopy in hollow-core optical fibres enable the detection of drugs at low concentrations as shown for the metabolites of the immunosuppressive drug 6-mercaptopurine as well as antimalarial agents. Furthermore, Raman spectroscopy can be used to characterise pathogenic bacteria in infectious diseases directly from body fluids, making time-consuming cultivation processes dispensable. Using the example of urinary tract infection, it is shown how bacteria can be identified from patients' urine samples within <1h. The methods cover both single-cell analysis and dielectrophoretic capturing of bacteria in suspension. The latter method could also be used for fast (<3.5h) identification of antibiotic resistance as shown exemplarily for vancomycin-resistant enterococci.

Authors: U. Neugebauer, ,

Date Published: 6th Nov 2015

Publication Type: Not specified

Rapid Identification of Pseudomonas spp. via Raman Spectroscopy Using Pyoverdine as Capture Probe

Abstract (Expand)

Pyoverdine is a substance which is excreted by fluorescent pseudomonads in order to scavenge iron from their environment. Due to specific receptors of the bacterial cell wall, the iron loaded pyoverdine … molecules are recognized and transported into the cell. This process can be exploited for developing efficient isolation and enrichment strategies for members of the Pseudomonas genus, which are capable of colonizing various environments and also include human pathogens like P. aeruginosa and the less virulent P. fluorescens. A significant advantage over antibody based systems is the fact that siderophores like pyoverdine can be considered as "immutable ligands," since the probability for mutations within the siderophore uptake systems of bacteria is very low. While each species of Pseudomonas usually produces structurally unique pyoverdines, which can be utilized only by the producer strain, cross reactivity does occur. In order to achieve a reliable identification of the captured pathogens, further investigations of the isolated cells are necessary. In this proof of concept study, we combine the advantages of an isolation strategy relying on "immutable ligands" with the high specificity and speed of Raman microspectroscopy. In order to isolate the bacterial cells, pyoverdine was immobilized covalently on planar aluminum chip substrates. After capturing, single cell Raman spectra of the isolated species were acquired. Due to the specific spectroscopic fingerprint of each species, the bacteria can be identified. This approach allows a very rapid detection of potential pathogens, since time-consuming culturing steps are unnecessary. We could prove that pyoverdine based isolation of bacteria is fully Raman compatible and further investigated the capability of this approach by isolating and identifying P. aeruginosa and P. fluorescens from tap water samples, which are both opportunistic pathogens and can pose a threat for immunocompromised patients.

Authors: S. Pahlow, S. Stockel, S. Pollok, D. Cialla-May, , K. Weber,

Date Published: 8th Jan 2016

Publication Type: Not specified

Regulation and Role of Fungal Secondary Metabolites.

Abstract (Expand)

Fungi have the capability to produce a tremendous number of so-called secondary metabolites, which possess a multitude of functions, e.g., communication signals during coexistence with other microorganisms, … virulence factors during pathogenic interactions with plants and animals, and in medical applications. Therefore, research on this topic has intensified significantly during the past 10 years and thus knowledge of regulatory mechanisms and the understanding of the role of secondary metabolites have drastically increased. This review aims to depict the complexity of all the regulatory elements involved in controlling the expression of secondary metabolite gene clusters, ranging from epigenetic control and signal transduction pathways to global and specific transcriptional regulators. Furthermore, we give a short overview on the role of secondary metabolites, focusing on the interaction with other microorganisms in the environment as well as on pathogenic relationships.

Authors: J. Macheleidt, D. J. Mattern, J. Fischer, T. Netzker, J. Weber, V. Schroeckh, V. Valiante, A. A. Brakhage

Date Published: 13th Oct 2016

Publication Type: Not specified

Regulation of gametogenesis and zoosporogenesis in Ulva linza (Chlorophyta): comparison with Ulva mutabilis and potential for laboratory culture

Abstract (Expand)

Green Ulvophyte macroalgae represent attractive model systems for understanding growth, development, and evolution. They are untapped resources for food, fuel, and high-value compounds, but can also … form nuisance blooms. To fully analyze green seaweed morphogenesis, controlled laboratory-based culture of these organisms is required. To date, only a single Ulvophyte species, Ulva mutabilis Foyn, has been manipulated to complete its whole life cycle in laboratory culture and to grow continuously under axenic conditions. Such cultures are essential to address multiple key questions in Ulva development and in algal-bacterial interactions. Here we show that another Ulva species, U. linza, with a broad geographical distribution, has the potential to be grown in axenic culture similarly to U. mutabilis. U. linza can be reliably induced to sporulate (form gametes and zoospores) in the laboratory, by cutting the relevant thallus tissue into small pieces and removing extracellular inhibitors (sporulation and swarming inhibitors). The germ cells work as an ideal feed stock for standardized algae cultures. The requirement of U. linza for bacterial signals to induce its normal morphology (particularly of the rhizoids) appears to have a species-specific component. The axenic cultures of these two species pave the way for future comparative studies of algal-microbial interactions.

Authors: E. F. Vesty, R. W. Kessler, , J. C. Coates

Date Published: 26th Jan 2015

Publication Type: Not specified

Rhizobactin B is the preferred siderophore by a novel Pseudomonas isolate to obtain iron from dissolved organic matter in peatlands.

Abstract (Expand)

Bacteria often release diverse iron-chelating compounds called siderophores to scavenge iron from the environment for many essential biological processes. In peatlands, where the biogeochemical cycle … of iron and dissolved organic matter (DOM) are coupled, bacterial iron acquisition can be challenging even at high total iron concentrations. We found that the bacterium Pseudomonas sp. FEN, isolated from an Fe-rich peatland in the Northern Bavarian Fichtelgebirge (Germany), released an unprecedented siderophore for its genus. High-resolution mass spectrometry (HR-MS) using metal isotope-coded profiling (MICP), MS/MS experiments, and nuclear magnetic resonance spectroscopy (NMR) identified the amino polycarboxylic acid rhizobactin and a novel derivative at even higher amounts, which was named rhizobactin B. Interestingly, pyoverdine-like siderophores, typical for this genus, were not detected. With peat water extract (PWE), studies revealed that rhizobactin B could acquire Fe complexed by DOM, potentially through a TonB-dependent transporter, implying a higher Fe binding constant of rhizobactin B than DOM. The further uptake of Fe-rhizobactin B by Pseudomonas sp. FEN suggested its role as a siderophore. Rhizobactin B can complex several other metals, including Al, Cu, Mo, and Zn. The study demonstrates that the utilization of rhizobactin B can increase the Fe availability for Pseudomonas sp. FEN through ligand exchange with Fe-DOM, which has implications for the biogeochemical cycling of Fe in this peatland.

Authors: S. Kugler, R. E. Cooper, J. Boessneck, K. Kusel, T. Wichard

Date Published: 7th Oct 2020

Publication Type: Journal

Role of Chemical Mediators in Aquatic Interactions across the Prokaryote-Eukaryote Boundary.

Abstract (Expand)

There is worldwide growing interest in the occurrence and diversity of metabolites used as chemical mediators in cross-kingdom interactions within aquatic systems. Bacteria produce metabolites to protect … and influence the growth and life cycle of their eukaryotic hosts. In turn, the host provides a nutrient-enriched environment for the bacteria. Here, we discuss the role of waterborne chemical mediators that are responsible for such interactions in aquatic multi-partner systems, including algae or invertebrates and their associated bacteria. In particular, this review highlights recent advances in the chemical ecology of aquatic systems that support the overall ecological significance of signaling molecules across the prokaryote-eukaryote boundary (cross-kingdom interactions) for growth, development and morphogenesis of the host. We emphasize the value of establishing well-characterized model systems that provide the basis for the development of ecological principles that represent the natural lifestyle and dynamics of aquatic microbial communities and enable a better understanding of the consequences of environmental change and the most effective means of managing community interactions.

Authors: T. Wichard, C. Beemelmanns

Date Published: 15th Aug 2018

Publication Type: Journal

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