TY - JOUR A1 - Weithoff, Guntram A1 - Taube, Anne A1 - Bolius, Sarah T1 - The invasion success of the cyanobacterium Cylindrospermopsis raciborskii in experimental mesocosms BT - genetic identity, grazing loss, competition and biotic resistance JF - Aquatic Invasions N2 - The potentially toxic, invasive cyanobacterium Cylindrospermopsis raciborskii, originating from sub-tropical regions, has spread into temperate climate zones in almost all continents. Potential factors in its success are temperature, light and nutrient levels. Grazing losses through zooplankton have been measured in the laboratory but are typically not regarded as a factor in (failed) invasion success. In some potentially suitable lakes, C. raciborskii has never been found, although it is present in water bodies close by. Therefore, we tested the invasive potential of three different isolates introduced into natural plankton communities using laboratory mesocosm experiments under three grazing levels: ambient zooplankton densities, removal of large species using 100 mu m mesh and a ca. doubling of large species. Three C. raciborskii isolates originating from the same geographic region (North-East Germany) were added separately to the four replicates of each treatment and kept in semi-continuous cultures for 21 days. Two isolates disappeared from the mesocosms and were also not viable in filtered lake water indicating that the lake water itself or the switch from culture medium to lake water led to the decay of the inoculated C. raciborskii. Only one out of the three isolates persisted in the plankton communities at a rather low level and only in the treatment without larger zooplankton. This result demonstrates that under potentially suitable environmental conditions, top-down control from zooplankton might hamper the establishment of C. raciborskii. Non-metric multidimensional scaling showed distinct variation in resident phytoplankton communities between the different grazing levels, thus differential grazing impact shaped the resident community in different ways allowing C. raciborskii only to invade under competitive (= low grazing pressure) conditions. Furthermore, even after invasion failure, the temporary presence of C. raciborskii influenced the phytoplankton community. KW - alien species KW - Cyanobacteria KW - competitive resistance KW - consumptive resistance KW - herbivory KW - harmful algae KW - microbial invasion Y1 - 2017 U6 - https://doi.org/10.3391/ai.2017.12.3.07 SN - 1798-6540 SN - 1818-5487 VL - 12 SP - 333 EP - 341 PB - Regional Euro-Asian Biological Invasions centre-reabic CY - Helsinki ER - TY - JOUR A1 - Pearson, Leanne A. A1 - Dittmann, Elke A1 - Mazmouz, Rabia A1 - Ongley, Sarah E. A1 - Neilan, Brett A. T1 - The genetics, biosynthesis and regulation of toxic specialized metabolites of cyanobacteria JF - Harmful algae N2 - The production of toxic metabolites by cyanobacterial blooms represents a significant threat to the health of humans and ecosystems worldwide. Here we summarize the current state of the knowledge regarding the genetics, biosynthesis and regulation of well-characterized cyanotoxins, including the microcystins, nodularin, cylindrospermopsin, saxitoxins and antitoxins, as well as the lesser-known marine toxins (e.g. lyngbyatoxin, aplysiatoxin, jamaicamides, barbamide, curacin, hectochlorin and apratoxins). (C) 2015 Elsevier B.V. All rights reserved. KW - Cyanobacteria KW - Cyanotoxins KW - Specialized metabolites KW - Genetics KW - Biosynthesis KW - Regulation Y1 - 2016 U6 - https://doi.org/10.1016/j.hal.2015.11.002 SN - 1568-9883 SN - 1878-1470 VL - 54 SP - 98 EP - 111 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schuurmans, Jasper Merijn A1 - Brinkmann, Bregje W. A1 - Makower, Katharina A1 - Dittmann, Elke A1 - Huisman, Jef A1 - Matthijs, Hans C. P. T1 - Microcystin interferes with defense against high oxidative stress in harmful cyanobacteria JF - Harmful algae N2 - Harmful cyanobacteria producing toxic microcystins are a major concern in water quality management. In recent years, hydrogen peroxide (H2O2) has been successfully applied to suppress cyanobacterial blooms in lakes. Physiological studies, however, indicate that microcystin protects cyanobacteria against oxidative stress, suggesting that H2O2 addition might provide a selective advantage for microcystin-producing (toxic) strains. This study compares the response of a toxic Microcystis strain, its non-toxic mutant, and a naturally non-toxic Microcystis strain to H2O2 addition representative of lake treatments. All three strains initially ceased growth upon H2O2 addition. Contrary to expectation, the non-toxic strain and non-toxic mutant rapidly degraded the added H2O2 and subsequently recovered, whereas the toxic strain did not degrade H2O2 and did not recover. Experimental catalase addition enabled recovery of the toxic strain, demonstrating that rapid H2O2 degradation is indeed essential for cyanobacterial survival. Interestingly, prior to H2O2 addition, gene expression of a thioredoxin and peroxiredoxin was much lower in the toxic strain than in its non-toxic mutant. Thioredoxin and peroxiredoxin are both involved in H2O2 degradation, and microcystin may potentially suppress their activity. These results show that microcystin-producing strains are less prepared for high levels of oxidative stress, and are therefore hit harder by H2O2 addition than non-toxic strains. KW - Cyanobacteria KW - Harmful algal blooms KW - Microcystins KW - Hydrogen peroxide KW - Microarrays KW - Microcystis aeruginosa Y1 - 2018 U6 - https://doi.org/10.1016/j.hal.2018.07.008 SN - 1568-9883 SN - 1878-1470 VL - 78 SP - 47 EP - 55 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Batista, A. M. M. A1 - Woodhouse, Jason Nicholas A1 - Grossart, Hans-Peter A1 - Giani, A. T1 - Methanogenic archaea associated to Microcystis sp. in field samples and in culture JF - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica N2 - Cyanobacterial mass developments impact the community composition of heterotrophic microorganisms with far-reaching consequences for biogeochemical and energy cycles of freshwater ecosystems including reservoirs. Here we sought to evaluate the temporal stability of methanogenic archaea in the water column and further scrutinize their associations with cyanobacteria. Monthly samples were collected from October 2009 to December 2010 in hypereutrophic Pampulha reservoir with permanently blooming cyanobacteria, and from January to December 2011 in oligotrophic Volta Grande reservoir with only sporadic cyanobacteria incidence. The presence of archaea in cyanobacterial cultures was investigated by screening numerous strains of Microcystis spp. from these reservoirs as well as from lakes in Europe, Asia, and North-America. We consistently determined the occurrence of archaea, in particular methanogenic archaea, in both reservoirs throughout the year. However, archaea were only associated with two strains (Microcystis sp. UFMG 165 and UFMG 175) recently isolated from these reservoirs. These findings do not implicate archaea in the occurrence of methane in the epilimnion of inland waters, but rather serve to highlight the potential of microhabitats associated with particles, including phytoplankton, to shelter unique microbial communities. KW - Cyanobacteria KW - Methanogenic archaea KW - Bacterial community composition KW - Microcystis sp KW - Tropical reservoir Y1 - 2018 U6 - https://doi.org/10.1007/s10750-018-3655-3 SN - 0018-8158 SN - 1573-5117 VL - 831 IS - 1 SP - 163 EP - 172 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Van Donk, Ellen A1 - Ianora, Adrianna A1 - Vos, Matthijs T1 - Induced defences in marine and freshwater phytoplankton a review JF - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica N2 - Many organisms have developed defences to avoid predation by species at higher trophic levels. The capability of primary producers to defend themselves against herbivores affects their own survival, can modulate the strength of trophic cascades and changes rates of competitive exclusion in aquatic communities. Algal species are highly flexible in their morphology, growth form, biochemical composition and production of toxic and deterrent compounds. Several of these variable traits in phytoplankton have been interpreted as defence mechanisms against grazing. Zooplankton feed with differing success on various phytoplankton species, depending primarily on size, shape, cell wall structure and the production of toxins and deterrents. Chemical cues associated with (i) mechanical damage, (ii) herbivore presence and (iii) grazing are the main factors triggering induced defences in both marine and freshwater phytoplankton, but most studies have failed to disentangle the exact mechanism(s) governing defence induction in any particular species. Induced defences in phytoplankton include changes in morphology (e.g. the formation of spines, colonies and thicker cell walls), biochemistry (such as production of toxins, repellents) and in life history characteristics (formation of cysts, reduced recruitment rate). Our categorization of inducible defences in terms of the responsible induction mechanism provides guidance for future work, as hardly any of the available studies on marine or freshwater plankton have performed all the treatments that are required to pinpoint the actual cue(s) for induction. We discuss the ecology of inducible defences in marine and freshwater phytoplankton with a special focus on the mechanisms of induction, the types of defences, their costs and benefits, and their consequences at the community level. KW - Defenses KW - Algae KW - Review KW - Plankton community KW - Cyanobacteria KW - Toxins Y1 - 2011 U6 - https://doi.org/10.1007/s10750-010-0395-4 SN - 0018-8158 SN - 1573-5117 VL - 668 IS - 1 SP - 3 EP - 19 PB - Springer CY - Dordrecht ER - TY - THES A1 - Barchewitz, Tino T1 - Impact of microcystin on the non-canonical localization of RubisCO in the toxic bloom-forming cyanobacterium Microcystis aeruginosa PCC7806 T1 - Einfluss von Microcystin auf die nicht-kanonische Lokalisierung von RubisCO im toxischen Blüten-bildenden Cyanobakterium Microcystis aeruginosa PCC7806 N2 - Cyanobacteria are an abundant bacterial group and are found in a variety of ecological niches all around the globe. They can serve as a real threat for fish or mammals and can restrict the use of lakes or rivers for recreational purposes or as a source of drinking water, when they form blooms. One of the most abundant bloom-forming cyanobacteria is Microcystis aeruginosa. In the first part of the study, the role and possible dynamics of RubisCO in M. aeruginosa during high-light irradiation were examined. Its response was analyzed on the protein and peptide level via immunoblotting, immunofluorescence microscopy and with high performance liquid chromatography (HPLC). It was revealed that large amounts of RubisCO were located outside of carboxysomes under the applied high light stress. RubisCO aggregated mainly underneath the cytoplasmic membrane. There it forms a putative Calvin-Benson-Bassham (CBB) super complex together with other enzymes of photosynthesis. This complex could be part of an alternative carbon-concentrating mechanism (CCM) in M. aeruginosa, which enables a faster, and energy saving adaptation to high light stress of the whole bloom. Furthermore, the re-localization of RubisCO was delayed in the microcystin-deficient mutant ΔmcyB and RubisCO was more evenly distributed over the cell in comparison to the wild type. Since ΔmcyB is not harmed in its growth, possibly other produced cyanopeptides as aeruginosin or cyanopeptolin also play a role in the stabilization of RubisCO and the putative CBB complex, especially in the microcystin-free mutant. In the second part of this work, the possible role of microcystin as an extracellular signaling peptide during the diurnal cycle was studied. HPLC analysis showed a strong increase of extracellular microcystin in the wild type when the population entered nighttime and it resumed into the next day as well. Together with the increase of extracellular microcystin, a strong decrease of protein-bound intracellular microcystin was observed via immunoblot analysis. Interestingly, the signal of the large subunit of RubisCO (RbcL) also diminished when high amounts of microcystin were present in the surrounding medium. Microcystin addition experiments to M. aeruginosa WT and ΔmcyB cultures support this observation, since the immunoblot signal of both subunits of RubisCO and CcmK, a shell protein of carboxysomes, diminished after the addition of microcystin. In addition, the fluctuation of cyanopeptolin during the diurnal cycle indicates a more prominent role of other cyanopeptides besides microcystin as a signaling peptide, intracellularly as well as extracellularly. N2 - Cyanobakterien können weltweit in einer Vielzahl von ökologischen Nischen gefunden werden. Sie stellen eine Gefahr für Eukaryoten wie Fische oder Säugetiere dar, und können auch die Nutzung von Seen oder Flüssen zu Erholungszwecken oder als Trinkwasserquelle beeinträchtigen, wenn sie an der Wasser-Luft Interphase Blüten bilden. Einer der häufigsten blütenbildenden Cyanobakterien ist der Stamm M. aeruginosa PCC7806, welcher in Cyanobakterienblüten auf der ganzen Welt gefunden werden kann. Im ersten Teil dieser Arbeit wurde die Funktion und mögliche Dynamiken von RubisCO während der Bildung und Aufrechterhaltung von dicht gewachsenen Blüten untersucht. Dafür wurden Schwachlicht-adaptierte M. aeruginosa Zellkulturen Starklicht ausgesetzt und deren Reaktion auf dem Protein- und Peptidlevel analysiert. Verwendete Analysemethoden waren Western Blots, Immunofluoreszenz-mikroskopie und Hochleistungsflüssigkeitschromatografie (HPLC). Es konnte aufgezeigt werden, dass unter der angewendeten Starklichtbehandlung große Mengen RubisCO außerhalb der Carboxysomen lokalisiert waren. Dabei konnte RubisCO hauptsächlich direkt unterhalb der zytoplasmatischen Membran in Form von Aggregaten nachgewiesen werden. Diese Aggregate sind möglicherweise Teil eines hypothetischen Calvin-Benson-Bassham Zyklus (CBB) Superkomplexes zusammen mit anderen Enzymen aus der Photosynthese. Dieser Komplex könnte Teil eines alternativen Kohlenstoff-Konzentrationsmechanismus in M. aeruginosa sein, welcher eine schnellere und energiesparendere Anpassung der Cyanobakterienblüte an Starklichtstress ermöglicht. Weiterhin erfolgte die Relokalisation von RubisCO in der Microcystin-freien Mutante ΔmcyB verzögert und RubisCO war homogener in der Zelle verteilt im Vergleich zum Wildtyp. Die Ergebnisse dieser Arbeit sind im Einklang mit vorherigen Publikationen zu der Funktion von Microcystin als Schutz gegen Proteinabbau in Folge der Bindung von Microcystin an das jeweilige Protein. Da ΔmcyB im Wachstum nicht eingeschränkt war, scheint es möglich, dass andere Cyanopeptoline wie Aeruginosin oder Cyanopeptolin die stabilisierende Funktion von Microcystin gegenüber RubisCO und den hypothetischen CBB Komplex übernehmen, vor allem in der Microcystin-freien Mutante. Im zweiten Teil dieser Arbeit wurde die mögliche extrazelluläre Funktion von Microcystin untersucht. HPLC-Analysen zeigen eine starke Zunahme an extrazellulärem Microcystin im Wildtyp als die Zellkultur in die Nachtphase übergegangen ist. Dieser Trend hat sich auch in den folgenden Tag hinein fortgesetzt. Zusammen mit der Zunahme an extrazellulärem Microcystin wurde eine starke Abnahme an proteingebundenem intrazellulärem Microcystin festgestellt, anhand von Western Blot-Untersuchungen. Interessanterweise verringerte sich die Signalstärke der großen Untereinheit von RubisCO (RbcL) im selben Zeitraum im Western Blot. Microcystin Zugabe-Experimente zu M. aeruginosa WT und ΔmcyB unterstützen diese Beobachtung, da das Western Blot-Signal für sowohl beide Untereinheiten von RubisCO als auch CcmK, ein Hüllenprotein der Carboxysomen, nach der Zugabe von Microcystin stark abnahm. Zusätzlich weist die Fluktuation des Cyanopeptolin-Signals während des Tag-Nacht Zyklus auf eine wichtigere Funktion von Cyanopeptiden abseits von Microcystin hin; als Signalpeptide, sowohl intrazellulär als auch extrazellulär. Diese Dissertation gibt neue Einsichten in Adaptionsprozesse von M. aeruginosa an Starklicht-Bedingungen. Der postulierte alternative Kohlenstoff-Konzentrations-mechanismus, welcher direkt unterhalb der zytoplasmatischen Membran stattfindet, gibt M. aeruginosa einen Vorteil gegenüber anderen Cyanobakterien, welche nur den in der Literatur anerkannten Carboxysomen-basierten Kohlenstoff-Konzentrations-mechanismus besitzen. Des Weiteren stärkt die vorliegende Arbeit die Hypothese, dass die eigentliche extrazelluläre Funktion von Microcystin die eines Signalstoffes ist, und nicht die eines antibiotischen Stoffes. KW - Cyanobacteria KW - Microcystis KW - Microcystin KW - RubisCO KW - Carbon concentrating mechanism KW - Cyanobakterien KW - Microcystin KW - Microcystis KW - Carboxysomen KW - Kohlenstoff-Konzentrationsmechanismus KW - RubisCO Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-508299 ER - TY - GEN A1 - Koussoroplis, Apostolos-Manuel A1 - Schwarzenberger, Anke A1 - Wacker, Alexander T1 - Diet quality determines lipase gene expression and lipase/esterase activity in Daphnia pulex N2 - We studied the short- (12 h) and long-term (144 h) response of Daphnia pulex lipases to quality shifts in diets consisting of different mixtures of the green alga Scenedesmus with the cyanobacterium Synechococcus, two species with contrasting lipid compositions. The lipase/esterase activity in both the gut and the body tissues had fast responses to the diet shift and increased with higher dietary contributions of Synechococcus. When screening the Daphnia genome for TAG lipases, we discovered a large gene-family expansion of these enzymes. We used a subset of eight genes for mRNA expression analyses and distinguished between influences of time and diet on the observed gene expression patterns. We identified five diet-responsive lipases of which three showed a sophisticated short- and long-term pattern of expression in response to small changes in food-quality. Furthermore, the gene expression of one of the lipases was strongly correlated to lipase/esterase activity in the gut suggesting its potentially major role in digestion. These findings demonstrate that the lipid-related enzymatic machinery of D. pulex is finely tuned to diet and might constitute an important mechanism of physiological adaptation in nutritionally complex environments. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 336 KW - Cyanobacteria KW - Digestive enzyme activity KW - Nutritional quality KW - Lipases Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395661 ER - TY - JOUR A1 - Koussoroplis, Apostolos-Manuel A1 - Schwarzenberger, Anke A1 - Wacker, Alexander T1 - Diet quality determines lipase gene expression and lipase/esterase activity in Daphnia pulex JF - Biology open : BiO N2 - We studied the short- (12 h) and long-term (144 h) response of Daphnia pulex lipases to quality shifts in diets consisting of different mixtures of the green alga Scenedesmus with the cyanobacterium Synechococcus, two species with contrasting lipid compositions. The lipase/esterase activity in both the gut and the body tissues had fast responses to the diet shift and increased with higher dietary contributions of Synechococcus. When screening the Daphnia genome for TAG lipases, we discovered a large gene-family expansion of these enzymes. We used a subset of eight genes for mRNA expression analyses and distinguished between influences of time and diet on the observed gene expression patterns. We identified five diet-responsive lipases of which three showed a sophisticated short- and long-term pattern of expression in response to small changes in food-quality. Furthermore, the gene expression of one of the lipases was strongly correlated to lipase/esterase activity in the gut suggesting its potentially major role in digestion. These findings demonstrate that the lipid-related enzymatic machinery of D. pulex is finely tuned to diet and might constitute an important mechanism of physiological adaptation in nutritionally complex environments. KW - Cyanobacteria KW - Digestive enzyme activity KW - Nutritional quality KW - Lipases Y1 - 2017 U6 - https://doi.org/10.1242/bio.022046 VL - 6 SP - 210 EP - 216 PB - The company of Biologists CY - Cambridge ER - TY - THES A1 - Dehm, Daniel T1 - Development of concepts for the genomic mining of novel secondary metabolites in symbiotic cyanobacteria N2 - Naturstoffe sind seit der goldenen Ära der Antibiotika von immer größerem Interesse, sowohl für die Grundlagenforschung als auch die Angewandten Wissenschaften, da sie die Hauptquelle für neuartige Pharmazeutika mit starken antibiotischen, anti-entzündlichen und Antitumor-Aktivitäten darstellen. Neben den technologischen Fortschritten im Bereich der Hochdurchsatz Genomsequenzierung und dem verbesserten Verständnis des modularen Aufbaus der Biosynthesewege von Sekundärmetaboliten, kam es auch zu einem Wechsel vom labor-gestützten Screening aktiver Zellextrakte hin zum Algorithmen-basierten in silico Screening nach neuen Naturstoff-Biosyntheseclustern. Obwohl die steigende Zahl verfügbarer Genomsequenzen zeigte, dass nicht-ribosomale Peptid-Synthetasen (NRPS), Polyketid-Synthasen (PKS), und ribosomal synthetisierte und posttranslational modifizierte Peptide (RiPPs) ubiquitär in allen Sparten des Lebens gefunden werden können, so zeigen einige Phyla wie Actinobakterien oder Cyanobakterien eine besonders hohe Dichte an Sekundärmetabolitclustern. Der fakultativ symbiotische, N2-fixierende Modellorganismus N. punctiforme PCC73102 ist ein terrestrisches typ-IV Cyanobakterium, welches nicht nur einen besonders hohen Anteil seines Genoms der Produktion von Sekundärmetaboliten widmet, sondern zusätzlich noch genetisch modifizierbar ist. Eine AntiSMASH Analyse des Genoms zeigte, dass N. punctiforme insgesamt sechzehn potentielle Sekundärmetabolitcluster besitzt, von denen aber bis heute nur zweien ein spezifisches Produkt zugewiesen werden konnte. Das macht N. punctiforme zu einem perfekten Testorganismus für die Entwicklung eines neuartigen kombinatorischen Genomic Mining Ansatzes zur Detektion von bislang unbeschriebenen Naturstoffen. Der neuartige Ansatz, der im Rahmen dieser Studie entwickelt wurde, stellt eine Kombination aus Genomic Mining, unabhängigen Monitoring-Techniken sowie modifizierten Kultivierungsbedingungen dar und führte nicht nur zu neuen Erkenntnissen im Bereich cyanobakterieller Naturstoffsynthese, sondern letztlich auch zur Entdeckung eines neuen, von N. punctiforme produzierten, Naturstoffs. Die Herstellung und Untersuchung einer Reporterstamm Bibliothek, bestehend aus je einem CFP-produzierenden Transkriptionsreporter für jedes der sechzehn Sekundärmetabolitcluster von N. punctiforme, zeigte, dass im Gegensatz zur Erwartung nicht alle Biosynthesecluster für die man kein Produkt nachweisen kann auch nicht exprimiert werden. Stattdessen konnten klar definierbare Expressionsmuster beschrieben werden, was deutlich machte, dass die Naturstoffproduktion einer engen Regulation unterliegt und nur ein kleiner Teil der Biosynthesecluster unter Standardbedingungen tatsächlich still sind. Darüber hinaus führte die Erhöhung der Lichtintensität sowie der Kohlenstoffdioxid-Verfügbarkeit zusammen mit der Kultivierung von N. punctiforme zu extrem hohen Zelldichten zu einer starken Erhöhung der gesamten metabolischen Aktivität des Organismus. Nähere Untersuchungen der Zellextrakte dieser hoch-dichte Kultivierungen führten letztlich zur Entdeckung einer neuartigen Gruppe von Microviridinen mit verlängerter Peptidsequenz, welche Microviridin N3-N9 genannt wurden. Sowohl die Kultivierung der Transkriptionsreporter als auch die RTqPCR-basierte Untersuchung der Transkriptionslevel der verschiedenen Biosynthesecluster zeigten, dass die hoch-Zelldichte Kultivierung von N. punctiforme zu einer Aktivierung von 50% der vorhandenen Sekundärmetabolitcluster führt. Im Gegensatz zu dieser sehr breit-gefächerten Aktivierung, führt die Co-Kultivierung von N. punctiforme in chemischen oder physischen Kontakt zu einer N-gehungerten Wirtspflanze (Blasia pusilla) zu einer sehr spezifischen Aktivierung der RIPP4 und RiPP3 Biosynthesecluster. Obwohl dieser Effekt mittels verschiedener unabhängiger Methoden bestätigt werden konnte und trotz intensiver Analysebemühungen, konnte jedoch keinem der beiden Cluster ein Produkt zugeordnet werden. Diese Studie stellt die erste weitreichende, systematische Analyse eines cyanobakteriellen Sekundärmetaboloms durch einen kombinatorischen Ansatz aus Genomic Mining und unabhängigen Monitoring-Techniken dar und kann als neue strategische Herangehensweise für die Untersuchung anderer Organismen hinsichtlich ihrer Sekundärmetabolit-Produktion dienen. Obwohl es bereits gut beschriebene einzelne Sekundärmetabolite gibt, wie beispielweise den Zelldifferenzierungsfaktor PatS in Anabaena sp. PCC7120, so ist der Grad an Regulation der in dieser Studie gezeigt werden konnte bislang beispiellos und die Entschlüsselung dieser Mechanismen könnte die Entdeckung neuer Naturstoffe stark beschleunigen. Daneben lassen die Ergebnisse aber auch darauf schließen, dass die Induktion der Biosynthesewege nicht das eigentliche Problem darstellt, sondern vielmehr die verlässliche Detektion deren Produkte. Die Erarbeitung neuer Analytik-Strategien könnte somit auch einen deutlichen Einfluss auf die Geschwindigkeit der Entdeckung neuer Naturstoffe haben. N2 - Since the golden era of antibiotics natural products are of ever growing interest to both basic research and applied sciences as they are the main source of new bioactive compounds delivering lead structures for new pharmaceuticals with potent antibiotic, anti-inflammatory or anti-cancer activities. Alongside the technological advances in high-throughput genome sequencing and the better understanding of the general organization of those modular biosynthetic assembly lines of secondary metabolites, there was also a shift from wet-lab screening of active cell extracts towards algorithm-based in silico screening for new natural product biosynthesis gene clusters (BGCs). Although the increasing availability of full genome sequences revealed that such non-ribosomal peptide synthetases (NRPS), polyketide synthases (PKS) and ribosomally synthesized and post-translationally modified peptides (RiPPs) can be found in all three kingdoms of life, certain phyla like actinobacteria and cyanobacteria show a very high density of these secondary metabolite BGCs. The facultative symbiotic, N2-fixing model organism N. punctiforme PCC73102 is a terrestrial type IV cyanobacterium that not only dedicates are very large fraction of its genome to secondary metabolite production but is also amenable to genetic modification. AntiSMASH analysis of the genome showed that there are sixteen potential secondary metabolite BGCs encoded in N. punctiforme, but until now there were only two compounds assigned to their respective BGC leaving the remaining fourteen orphan. This makes the organism a perfect subject for the establishment of a novel combinatorial genomic mining approach for the detection of new natural products. In the course of this study a combinatorial approach of genomic mining, independent monitoring techniques and alteration of cultivation conditions lead to new insights in cyanobacterial natural product biosynthesis and ultimately to the description of a novel compound produced by N. punctiforme. With the generation and investigation of a reporter strain library consisting of CFP-producing transcriptional reporter mutants for every predicted secondary metabolite BGC of N. punctiforme, it could be shown that natural product expression is in fact not silent for all those BGCs where no compound can be detected. Instead several distinct expression patterns could be described highlighting that secondary metabolite production is under tight regulation and only a minor fraction of these BGCs is in fact silent under standard laboratory conditions. Furthermore, increasing light intensity and carbon dioxide availability and cultivating N. punctiforme to very high cell densities had a tremendous impact on the overall metabolic activity of the organism. Investigation of high density cultivated cell extracts ultimately lead to the detection of a so far undescribed set of microviridins with unusual extended peptide sequences named Microviridin N3 – N9. Both cultivation of the transcriptional reporter mutants as well as RTqPCR-based detection of secondary metabolite BGC transcription levels revealed that in fact 50% of N. punctiforme’s natural product BGCs are upregulated under high cell density conditions. In contrast to this very broad response, co-cultivation of N. punctiforme in chemical or physical contact with a N-deprived host plant (Blasia pusilla) lead to a very specific upregulation of two natural product BGCs, namely RIPP3 and RIPP4. Although this response could be confirmed by various independent monitoring techniques and heavy analytical efforts were spent, no compound could be assigned to either of these BGCs. This study is the first in-depth systematic investigation of a cyanobacterial secondary metabolome by a combinatorial approach of genome mining and independent monitoring techniques that can serve as a new strategic approach to gain further insight into natural product synthesis of various organisms. Although there are single well described examples of secondary metabolites like the cell differentiation factor PatS in Anabaena sp. strain PCC 7120, the level and extent of regulation observed in this study is unprecedented and understanding of these mechanisms might be the key to streamline natural product discovery. However, the results of this study also highlight that induction of secondary metabolite BGCs is not the real challenge. Instead the new insights point towards analytical issues being a severe hurdle and finding reliable strategies to overcome these problems might as well drive natural product discovery. T2 - Entwicklung von Konzepten für das Genomic Mining von neuartigen Sekundärmetaboliten in symbiotischen Cyanobakterien KW - Cyanobacteria KW - Cyanobakterien KW - Natural Products KW - Naturstoffe KW - Genomic Mining KW - Secondary Metabolites KW - Sekundärmetabolite KW - Nostoc punctiforme Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-478342 ER - TY - JOUR A1 - Krumbholz, Julia A1 - Ishida, Keishi A1 - Baunach, Martin A1 - Teikari, Jonna A1 - Rose, Magdalena M. A1 - Sasso, Severin A1 - Hertweck, Christian A1 - Dittmann, Elke T1 - Deciphering chemical mediators regulating specialized metabolism in a symbiotic cyanobacterium JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker. International edition N2 - Genomes of cyanobacteria feature a variety of cryptic biosynthetic pathways for complex natural products, but the peculiarities limiting the discovery and exploitation of the metabolic dark matter are not well understood. Here we describe the discovery of two cell density-dependent chemical mediators, nostoclide and nostovalerolactone, in the symbiotic model strain Nostoc punctiforme, and demonstrate their pronounced impact on the regulation of specialized metabolism. Through transcriptional, bioinformatic and labeling studies we assigned two adjacent biosynthetic gene clusters to the biosynthesis of the two polyketide mediators. Our findings provide insight into the orchestration of specialized metabolite production and give lessons for the genomic mining and high-titer production of cyanobacterial bioactive compounds. KW - Biosynthesis KW - Cyanobacteria KW - Genomic Mining KW - Quorum Sensing KW - Specialized KW - Metabolism Y1 - 2022 U6 - https://doi.org/10.1002/anie.202204545 SN - 1433-7851 SN - 1521-3773 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Frijia, Gianluca A1 - Forkner, R. A1 - Minisini, D. A1 - Pacton, M. A1 - Struck, Ulrich A1 - Mutti, Maria T1 - Cyanobacteria proliferation in the cenomanian-turonian boundary interval of the apennine carbonate platform: BT - immediate response to the environmental perturbations associated with OAE-2? JF - Geochemistry, geophysics, geosystems N2 - Oceanic Anoxic Event-2 (OAE-2; Cenomanian-Turonian) is characterized by extensive deposition of organic carbon-rich deposits (black shales) in ocean basins worldwide as result of a major perturbation of the global carbon cycle. While the sedimentological, geochemical, and paleontological aspects of deep water expressions of OAE-2 have been intensively studied in the last few decades, much less attention has been given to the coeval shallow water deposits. In this study, we present the results of a detailed facies and petrographic (optical microscope and scanning electron microscopy) and geochemical studies (delta C-13(carb), delta C-13 (org), delta N-15(bulk), TOC, and Rock-Eval pyrolysis) on two key shallow marine sections from the Apennine Carbonate Platform (ACP; Italy). Here a continuous record of shallow water carbonates through the OAE-2 interval is preserved, offering the unique opportunity to document the archive of paleoenvironmental changes in a neritic setting, at a tropical latitude and far from the influence of a large continental block. Two conspicuous intervals are characterized by abundant and closely spaced dark microbial laminites found at correlative stratigraphic horizons in the two stratigraphic sections. These laminites contain elevated concentrations of TOC (up to 1%) relative to microbial capping cycles laminites stratigraphically above and below. The organic matter preserved in these fine-grained laminites is dominated by cyanobacteria remains, which accounted for most of the organic matter produced on the ACP in these intervals. Our study suggests that Tethyan carbonate platforms experienced significant biological changes during OAE-2, alternating, in few kiloyears, between eutrophic phases dominated by microbial communities and mesotrophic/oligotrophic conditions favoring normal carbonate production/sedimentation. The synchronous occurrence of microbialite facies at different locations across the ACP and on other platforms worldwide (e.g., Mexico and Croatia) suggests a causal link between Large Igneous Province volcanism and the environmental conditions necessary to trigger cyanobacterial proliferation on shallow carbonate platforms. KW - OAE-2 KW - Apennine Carbonate Platform (ACP) KW - Cyanobacteria KW - C isotopes KW - N isotopes Y1 - 2019 U6 - https://doi.org/10.1029/2019GC008306 SN - 1525-2027 VL - 20 IS - 6 SP - 2698 EP - 2716 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Liaimer, Anton A1 - Jensen, John B. A1 - Dittmann, Elke T1 - A Genetic and Chemical Perspective on Symbiotic Recruitment of Cyanobacteria of the Genus Nostoc into the Host Plant Blasia pusilla L. JF - Frontiers in microbiology N2 - Liverwort Blasia pusilla L. recruits soil nitrogen-fixing cyanobacteria of genus Nostoc as symbiotic partners. In this work we compared Nostoc community composition inside the plants and in the soil around them from two distant locations in Northern Norway. STRR fingerprinting and 16S rDNA phylogeny reconstruction showed a remarkable local diversity among isolates assigned to several Nostoc clades. An extensive web of negative allelopathic interactions was recorded at an agricultural site, but not at the undisturbed natural site. The cell extracts of the cyanobacteria did not show antimicrobial activities, but four isolates were shown to be cytotoxic to human cells. The secondary metabolite profiles of the isolates were mapped by MALDI-TOF MS, and the most prominent ions were further analyzed by Q-TOF for MS/MS aided identification. Symbiotic isolates produced a great variety of small peptide-like substances, most of which lack any record in the databases. Among identified compounds we found microcystin and nodularin variants toxic to eukaryotic cells. Microcystin producing chemotypes were dominating as symbiotic recruits but not in the free-living community. In addition, we were able to identify several novel aeruginosins and banyaside-like compounds, as well as nostocyclopeptides and nosperin. KW - Cyanobacteria KW - secondary metabolites KW - symbiosis KW - Blasia KW - Nostoc KW - allelopathy Y1 - 2016 U6 - https://doi.org/10.3389/fmicb.2016.01693 SN - 1664-302X VL - 7 SP - 449 EP - 474 PB - Frontiers Research Foundation CY - Lausanne ER -