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7. Fungi from metal-polluted streams may have high ability to cope with the oxidative stress induced by copper oxide nanoparticles

Author

Pradhan, A., Seena, S., Schlosser, Dietmar, Gerth, K., Helm, S., Dobritzsch, M., Krauss, G.-J., Dobritzsch, D., Pascoal, C., Cássio, F., Pradhan, A., Seena, S., Schlosser, Dietmar, Gerth, K., Helm, S., Dobritzsch, M., Krauss, G.-J., Dobritzsch, D., Pascoal, C., and Cássio, F.

Abstract

Increased commercialization of products based on metal oxide nanoparticles increases the likelihood that these nanoparticles will be released into aquatic environments, thus making relevant the assessment of their potential impacts on aquatic biota. Aquatic fungi are distributed worldwide and play a key role in organic matter turnover in freshwater ecosystems. The present study investigated the impacts of copper oxide spherical nanoparticles (CuO-NPs; <50 nm powder, 5 levels ≤200 mg/L) on cellular targets and antioxidant defenses in 5 fungal isolates collected from metal-polluted or nonpolluted streams. The CuO-NPs induced oxidative stress in aquatic fungi, as evidenced by intracellular accumulation of reactive oxygen species, and led to plasma membrane damage and DNA strand breaks in a concentration-dependent manner. Effects were more pronounced with a longer exposure time (3 d vs 10 d). Under CuO-NP exposure, mycelia of fungi collected from metal-polluted streams showed less oxidative stress and higher activities of superoxide dismutase and glutathione reductase compared with fungi from nonpolluted streams. The latter fungi responded to CuO-NPs with a stronger stimulation of glutathione peroxidase activity. These findings may indicate that fungi isolated from metal-polluted streams had a greater ability to maintain the pool of reduced glutathione than those from nonpolluted streams. Overall, results suggest that populations adapted to metals may develop mechanisms to cope with the oxidative stress induced by metal nanoparticles

Published
2015

8. Physiological responses to nanoCuO in fungi from non-polluted and metal-polluted streams

Author

Pradhan, A., Seena, S., Dobritzsch, D., Helm, S., Gerth, K., Dobritzsch, M., Krauss, G.-J., Schlosser, Dietmar, Pascoal, C., Cássio, F., Pradhan, A., Seena, S., Dobritzsch, D., Helm, S., Gerth, K., Dobritzsch, M., Krauss, G.-J., Schlosser, Dietmar, Pascoal, C., and Cássio, F.

Abstract

Nanocopper oxide (nanoCuO) is among the most widely used metal oxide nanoparticles which increases their chance of being released into freshwaters. Fungi are the major microbial decomposers of plant litter in streams. Fungal laccases are multicopper oxidase enzymes that are involved in the degradation of lignin and various xenobiotic compounds. We investigated the effects of nanoCuO (5 levels, ≤ 200 mg L− 1) on four fungal isolates collected from metal-polluted and non-polluted streams by analyzing biomass production, changes in mycelial morphology, laccase activity, and quantifying copper adsorbed to mycelia, and ionic and nanoparticulate copper in the growth media. The exposure to nanoCuO decreased the biomass produced by all fungi in a concentration- and time-dependent manner. Inhibition of biomass production was stronger in fungi from non-polluted (EC50(10 days) ≤ 31 mg L− 1) than from metal-polluted streams (EC50(10 days) ≥ 65.2 mg L− 1). NanoCuO exposure led to cell shrinkage and mycelial degeneration, particularly in fungi collected from non-polluted streams. Adsorption of nanoCuO to fungal mycelia increased with the concentration of nanoCuO in the medium and was higher in fungi from non-polluted streams. Extracellular laccase activity was induced by nanoCuO in two fungal isolates in a concentration-dependent manner, and was highly correlated with adsorbed Cu and/or ionic Cu released by dissolution from nanoCuO. Putative laccase gene fragments were also detected in these fungi. Lack of substantial laccase activity in the other fungal isolates was corroborated by the absence of laccase-like gene fragments.

Published
2013

10. Complete genome sequence of the myxobacterium Sorangium cellulosum

Author

Schneiker, S, Perlova, O, Kaiser, O, Gerth, K, Alici, A, Altmeyer, MO, Bartels, D, Bekel, T, Beyer, S, Bode, E HB, Bolten, CJ, Choudhuri, JV, Doss, S, Elnakady, YA, Frank, B, Gaigalat, L, Goesmann, A, Groeger, C, Gross, F, Jelsbak, Lars, Kalinowski, J, Kegler, C, Knauber, T, Konietzny, S, Kopp, M, Krause, L, Krug, D, Linke, B, Mahmud, T, Martinez-Arias, R, McHardy, AC, Merai, M, Meyer, F, Mormann, S, Muñoz-Dorado, J, Perez, J, Pradella, S, Rachid, S, Raddatz, G, Rosenau, F, Rückert, C, Sasse, F, Scharfe, M, Schuster, SC, Suen, G, Treuner-Lange, A, Velicer, GJ, Vorhölter, FJ, Weissman, KJ, Welch, RD, Wenzel, SC, Whitworth, DE, Wilhelm, S, Wittmann, C, Blöcker, H, Pühler, A, Müller, R, Schneiker, S, Perlova, O, Kaiser, O, Gerth, K, Alici, A, Altmeyer, MO, Bartels, D, Bekel, T, Beyer, S, Bode, E HB, Bolten, CJ, Choudhuri, JV, Doss, S, Elnakady, YA, Frank, B, Gaigalat, L, Goesmann, A, Groeger, C, Gross, F, Jelsbak, Lars, Kalinowski, J, Kegler, C, Knauber, T, Konietzny, S, Kopp, M, Krause, L, Krug, D, Linke, B, Mahmud, T, Martinez-Arias, R, McHardy, AC, Merai, M, Meyer, F, Mormann, S, Muñoz-Dorado, J, Perez, J, Pradella, S, Rachid, S, Raddatz, G, Rosenau, F, Rückert, C, Sasse, F, Scharfe, M, Schuster, SC, Suen, G, Treuner-Lange, A, Velicer, GJ, Vorhölter, FJ, Weissman, KJ, Welch, RD, Wenzel, SC, Whitworth, DE, Wilhelm, S, Wittmann, C, Blöcker, H, Pühler, A, and Müller, R

Published
2007

28. New Natural Epothilones from Sorangium cellulosum, Strains So ce90/B2 and So ce90/D13:  Isolation, Structure Elucidation, and SAR Studies

Author

Hardt, I. H., Steinmetz, H., Gerth, K., Sasse, F., Reichenbach, H., and Hofle, G.

Abstract

In addition to epothilones A (1) and B (2), 37 natural epothilone variants and epothilone-related compounds were isolated from the culture broth of a 700 L fermentation of Sorangium cellulosum, strain So ce90/B2. Of these, only the 12,13-desoxyepothilones, epothilone C (14) and D (15), were produced in significant amounts (3−6 mg/L); the 21-hydroxy derivatives and epothilones E (3) and F (4), in low and variable amounts due to further degradation by the producing organism. Most of the other epothilone variants were produced only in 1−100 μg/L amounts. The new compounds are very similar in structure to the parent compounds 1, 2 and 14, 15 and are presumably the result of the imperfect selectivity of the biosynthetic enzymes for acetate and propionate. Further, epothilones containing an oxazole moiety (10−13) in the side chain instead of a thiazole as well as ring-expanded 18-membered macrolides, epothilones I (30−35), and a ring contracted 14-membered macrolide, epothilone K (36), were found as very minor metabolites. The mutant strain, So ce90/D13, instead of macrolactones, produced short-chain carboxylic acids 40, 41, and 42 bearing the characteristic thiazole side chain. The structures of the new epothilones were elucidated on the basis of comprehensive NMR and MS data. The new epothilone variants were tested in a cytotoxicity assay with mouse fibroblasts (cell line L929), and structure−activity relationships were established. Several new natural epothilones showed activity comparable to 1 and 2, but in no case exceeded that of 2.

Published
2001

43. Novel expression hosts for complex secondary metabolite megasynthetases: Production of myxochromide in the thermopilic isolate Corallococcus macrosporus GT-2

Author

Zhang Youming, Kuhlmann Silvia, Gerth Klaus, Perlova Olena, and Müller Rolf

Subjects
Microbiology, QR1-502
Abstract

Abstract Although many secondary metabolites with diverse biological activities have been isolated from myxobacteria, most strains of these biotechnologically important gliding prokaryotes remain difficult to handle genetically. In this study we describe the new fast growing myxobacterial thermophilic isolate GT-2 as a heterologous host for the expression of natural product biosynthetic pathways isolated from other myxobacteria. According to the results of sequence analysis of the 16S rDNA, this moderately thermophilic isolate is closely related to Corallococcus macrosporus and was therefore named C. macrosporus GT-2. Fast growth of moderately thermophilic strains results in shorter fermentation and generation times, aspects which are of significant interest for molecular biological work as well as production of secondary metabolites. Development of a genetic manipulation system allowed the introduction of the complete myxochromide biosynthetic gene cluster, located on a transposable fragment, into the chromosome of GT-2. Genetic engineering of the biosynthetic gene cluster by promoter exchange leads to much higher production of myxochromides in the heterologous host C. macrosporus GT-2 in comparison to the original producer Stigmatella aurantiaca and to the previously described heterologous host Pseudomonas putida (600 mg/L versus 8 mg/L and 40 mg/L, respectively).

Published
2009
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50. Transnational trauma: trauma and psychiatry in the world and Taiwan, 1945-1995

Author

Wu, H, Mahone, S, and Gerth, K

Subjects
International,imperial and global history, History of medicine, History of Asia & Far East
Abstract

This study considers the history of trauma, both as a psychiatric concept and as a diagnosis, and its social and cultural representation from a transnational perspective after WWII. The intellectual evolution of trauma was determined by various medical, social and cultural variables, institutions, and people who wielded influence in the postwar world order as well as diverse local contexts. This thesis focuses on the globalisation and localisation of such concept and diagnosis shaped by international and local mental health experts at the World Health Organization and the National Taiwan University Hospital. Through the efforts of these experts, trauma not only became one of the most globally diffused psychiatric diagnoses, but also a hyperbole appropriated by Taiwanese psychiatrists to account for extreme forms of social suffering.Studies have criticised the universality and the Anglo-American-centred approach to the history of traumatic psychiatry. Scholars have also begun to explore transnational histories of psychiatry by systematically comparing or tracing the diffusion routes of psychiatric topics. Their methods of enquiry and problems solved, however, differ. My research analyses a disparate collection of evidence at the level of international organisations and from local aspects, allowing not only a critical reconsideration of trauma in the trend of global medicine, but also its reception, contestation and appropriation in the non-Western contexts. Guided by the works of medical historians, literary critics and cultural anthropologists, this project combines archival research with oral history interviews to challenge the existing historical accounts of trauma, and provide evidence of the limited capacity of globalised psychiatric norms and their reception and appropriation beyond the imagination of world citizenship. It argues that such scientific artefacts were not only produced through mutual reference between Eastern and Western experiences, but also measures of instrumental rationality employed by postwar internationalists to engineer their modernity in the Global South.

Published
2016

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