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153 Publications visible to you, out of a total of 153
Bacteria induce pigment formation in the basidiomycete Serpula lacrymans

Abstract (Expand)

Basidiomycete fungi are characterized ecologically for their vital functional role in ecosystem carbon recycling and chemically for their capacity to produce a diverse array of small molecules. … Chromophoric natural products derived from the quinone precursor atromentin, such as variegatic acid and involutin, have been shown to function in redox cycling. Yet, in the context of an inter-kingdom natural system these pigments are still elusive. Here, we co-cultured the model saprotrophic basidiomycete Serpula lacrymans with an ubiquitous terrestrial bacterium, either Bacillus subtilis, Pseudomonas putida, or Streptomyces iranensis. For each, there was induction of the gene cluster encoding a non-ribosomal peptide synthetase-like enzyme (atromentin synthetase) and an aminotransferase which together produce atromentin. Correspondingly during co-culturing there was an increase in secreted atromentin-derived pigments, i.e., variegatic, xerocomic, isoxerocomic and atromentic acid. Bioinformatic analyses from 14 quinone synthetase genes, twelve of which are encoded in a cluster, identified a common promoter motif indicating a general regulatory mechanism for numerous basidiomycetes. This article is protected by copyright. All rights reserved.

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Date Published: 5th Oct 2016

Publication Type: Not specified

Bacteria-induced morphogenesis of Ulva intestinalis and Ulva mutabilis (Chlorophyta): a contribution to the lottery theory.

Abstract (Expand)

The green marine macroalgae of the class Ulvophyceae (Ulvophytes) are common algae distributed worldwide particularly in intertidal areas, which play a key role in aquatic ecosystems. They are potentially … valuable resources for food, animal feed and fuel but can also cause massive nuisance blooms. Members of Ulvaceae, like many other seaweeds, harbour a rich diversity of epiphytic bacteria with functions related to host growth and morphological development. In the absence of appropriate bacterially derived signals, germ cells of the genus Ulva develop into 'atypical' colonies consisting of undifferentiated cells with abnormal cell walls. This paper examines the specificity of bacteria-induced morphogenesis in Ulva, by cross-testing bacteria isolated from several Ulva species on two Ulva species, the emerging model system Ulva mutabilis and the prominent biofouler species Ulva intestinalis. We show that pairs of bacterial strains isolated from species other than U. mutabilis and U. intestinalis can fully rescue axenic plantlets generated either from U. mutabilis or U. intestinalis gametes. This laboratory-based study demonstrates that different compositions of microbial communities with similar functional characteristics can enable complete algal morphogenesis and thus supports the 'competitive lottery' theory for how symbiotic bacteria drive algal development.

Authors: F. Ghaderiardakani, J. C. Coates, T. Wichard

Date Published: 16th Aug 2017

Publication Type: Not specified

Bacterial endosymbionts protect beneficial soil fungus from nematode attack.

Abstract (Expand)

Fungi of the genus Mortierella occur ubiquitously in soils where they play pivotal roles in carbon cycling, xenobiont degradation, and promoting plant growth. These important fungi are, however, … threatened by micropredators such as fungivorous nematodes, and yet little is known about their protective tactics. We report that Mortierella verticillata NRRL 6337 harbors a bacterial endosymbiont that efficiently shields its host from nematode attacks with anthelmintic metabolites. Microscopic investigation and 16S ribosomal DNA analysis revealed that a previously overlooked bacterial symbiont belonging to the genus Mycoavidus dwells in M. verticillata hyphae. Metabolic profiling of the wild-type fungus and a symbiont-free strain obtained by antibiotic treatment as well as genome analyses revealed that highly cytotoxic macrolactones (CJ-12,950 and CJ-13,357, syn necroxime C and D), initially thought to be metabolites of the soil-inhabiting fungus, are actually biosynthesized by the endosymbiont. According to comparative genomics, the symbiont belongs to a new species (Candidatus Mycoavidus necroximicus) with 12% of its 2.2 Mb genome dedicated to natural product biosynthesis, including the modular polyketide-nonribosomal peptide synthetase for necroxime assembly. Using Caenorhabditis elegans and the fungivorous nematode Aphelenchus avenae as test strains, we show that necroximes exert highly potent anthelmintic activities. Effective host protection was demonstrated in cocultures of nematodes with symbiotic and chemically complemented aposymbiotic fungal strains. Image analysis and mathematical quantification of nematode movement enabled evaluation of the potency. Our work describes a relevant role for endofungal bacteria in protecting fungi against mycophagous nematodes.

Authors: H. Buttner, S. P. Niehs, K. Vandelannoote, Z. Cseresnyes, B. Dose, I. Richter, R. Gerst, M. T. Figge, T. P. Stinear, S. J. Pidot, C. Hertweck

Date Published: 14th Sep 2021

Publication Type: Journal

Bakterien-induzierte Morphogenese der marinen Makroalge Ulva

Abstract (Expand)

The morphogenesis of the marine green algae Ulva mutabilis depends on bacteria that release diffusible morphogenetic compounds. Axenic U. mutabilis gametes develop into callus-like colonies without … normal cell walls. From the accompanying microbial flora two specific bacteria were isolated, which form a symbiotic tripartite community and induce readily algal morphogenesis. We use axenic algal cultures as a powerful tool to investigate the multiple cross-kingdom interactions on a molecular level.

Author: Thomas Wichard

Date Published: 2nd Oct 2016

Publication Type: Not specified

Benefits of jasmonate-dependent defenses against vertebrate herbivores in nature.

Abstract (Expand)

Endogenous jasmonates are important regulators of plant defenses. If and how they enable plants to maintain their reproductive output when facing community-level herbivory under natural conditions, … however, remains unknown. We demonstrate that jasmonate-deficient Nicotiana attenuata plants suffer more damage by arthropod and vertebrate herbivores than jasmonate-producing plants in nature. However, only damage by vertebrate herbivores translates into a significant reduction in flower production. Vertebrate stem peeling has the strongest negative impact on plant flower production. Stems are defended by jasmonate-dependent nicotine, and the native cottontail rabbit Sylvilagus nuttallii avoids jasmonate-producing N. attenuata shoots because of their high levels of nicotine. Thus, endogenous jasmonates enable plants to resist different types of herbivores in nature, and jasmonate-dependent defenses are important for plants to maintain their reproductive potential when facing vertebrate herbivory. Ecological and evolutionary models on plant defense signaling should aim at integrating arthropod and vertebrate herbivory at the community level.

Authors: R. A. Machado, M. McClure, M. R. Herve, I. T. Baldwin, M. Erb

Date Published: 30th Jun 2016

Publication Type: Not specified

Biocatalytic Production of Psilocybin and Derivatives in Tryptophan Synthase-Enhanced Reactions.

Abstract (Expand)

Psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine) is the main alkaloid of the fungal genus Psilocybe, the so-called "magic mushrooms." The pharmaceutical interest in this psychotropic natural … product as a future medication to treat depression and anxiety is strongly re-emerging. Here, we present an enhanced enzymatic route of psilocybin production by adding TrpB, the tryptophan synthase of the mushroom Psilocybe cubensis, to the reaction. We capitalized on its substrate flexibility and show psilocybin formation from 4-hydroxyindole and l-serine, which are less cost-intensive substrates, compared to the previous method. Furthermore, we show enzymatic production of 7-phosphoryloxytryptamine (isonorbaeocystin), a non-natural congener of the Psilocybe alkaloid norbaeocystin (4-phosphoryloxytryptamine), and of serotonin (5-hydroxytryptamine) by means of the same in vitro approach.

Authors: F. Blei, F. Baldeweg, J. Fricke, D. Hoffmeister

Date Published: 11th May 2018

Publication Type: Journal

Biodiversity and Activity of the Gut Microbiota across the Life History of the Insect Herbivore Spodoptera littoralis

Abstract (Expand)

Microbes that live inside insects play critical roles in host nutrition, physiology, and behavior. Although Lepidoptera (butterflies and moths) are one of the most diverse insect taxa, their microbial … symbionts are little-studied, particularly during metamorphosis. Here, using ribosomal tag pyrosequencing of DNA and RNA, we investigated biodiversity and activity of gut microbiotas across the holometabolous life cycle of Spodoptera littoralis, a notorious agricultural pest worldwide. Proteobacteria and Firmicutes dominate but undergo a structural "metamorphosis" in tandem with its host. Enterococcus, Pantoea and Citrobacter were abundant and active in early-instar, while Clostridia increased in late-instar. Interestingly, only enterococci persisted through metamorphosis. Female adults harbored high proportions of Enterococcus, Klebsiella and Pantoea, whereas males largely shifted to Klebsiella. Comparative functional analysis with PICRUSt indicated that early-instar larval microbiome was more enriched for genes involved in cell motility and carbohydrate metabolism, whereas in late-instar amino acid, cofactor and vitamin metabolism increased. Genes involved in energy and nucleotide metabolism were abundant in pupae. Female adult microbiome was enriched for genes relevant to energy metabolism, while an increase in the replication and repair pathway was observed in male. Understanding the metabolic activity of these herbivore-associated microbial symbionts may assist the development of novel pest-management strategies.

Authors: B. Chen, , C. Sun, S. Hu, X. Lu, , Y. Shao

Date Published: 9th Jul 2016

Publication Type: Not specified

Biophysical characterization and antineoplastic activity of new bis(thiosemicarbazonato) Cu(II) complexes

Abstract (Expand)

Aiming to explore alternative mechanisms of cellular uptake and cytotoxicity, we have studied a new family of copper(II) complexes (CuL1-CuL4) with bis(thiosemicarbazone) (BTSC) ligands containing … pendant protonable cyclic amines (morpholine and piperidine). Herein, we report on the synthesis and characterization of these new complexes, as well as on their biological performance (cytotoxic activity, cellular uptake, protein and DNA binding), in comparison with the parental CuIIATSM (ATSM=diacetyl-bis(N4-methylthiosemicarbazonate) complex without pendant cyclic amines. The new compounds have been characterized by a range of analytical techniques including ESI-MS, IR spectroscopy, cyclic voltammetry, reverse-phase HPLC and X-ray spectroscopy. In vitro cytotoxicity studies revealed that the copper complexes are cytotoxic, unlike the corresponding ligands, with a similar potency to that of CuATSM. Unlike CuATSM, the new complexes were able to circumvent cisplatin cross-resistance. The presence of the protonable cyclic amines did not lead to an enhancement of the interaction of the complexes with human serum albumin or calf thymus DNA. However, CuL1-CuL4 showed a remarkably augmented cellular uptake compared with CuATSM, as proved by uptake, internalization and externalization studies that were performed using the radioactive congeners 64CuL1-64CuL4. The enhanced cellular uptake of CuL1-CuL4 indicates that this new family of CuIIBTSC complexes deserves to be further evaluated in the design of metallodrugs for cancer theranostics.

Authors: E. Palma, F. Mendes, G. R. Morais, I. Rodrigues, I. C. Santos, M. P. Campello, P. Raposinho, I. Correia, S. Gama, D. Belo, V. Alves, A. J. Abrunhosa, I. Santos, A. Paulo

Date Published: 3rd Dec 2016

Publication Type: Not specified

Biosynthesis of Sinapigladioside, an Antifungal Isothiocyanate from Burkholderia Symbionts.

Abstract (Expand)

Sinapigladioside is a rare isothiocyanate-bearing natural product from beetle-associated bacteria ( Burkholderia gladioli ) that may protect the beetle offspring against entomopathogenic fungi. The … biosynthetic origin of sinapigladioside has been elusive, and little is known about bacterial isothiocyanate biosynthesis in general. On the basis of stable-isotope labeling, bioinformatics, and mutagenesis we identified the sinapigladioside biosynthesis gene cluster in the symbiont and found that an isonitrile synthase plays a key role in the biosynthetic pathway. Genome mining and network analyses indicate that related gene clusters are distributed across various bacterial phyla including producers of both nitriles and isothiocyanates. Our findings support a model for bacterial isothiocyanate biosynthesis by sulfur transfer onto isonitrile precursors.

Authors: B. Dose, S. P. Niehs, K. Scherlach, S. Shahda, L. V. Florez, M. Kaltenpoth, C. Hertweck

Date Published: 19th Mar 2021

Publication Type: Journal

Both Biosynthesis and Transport Are Involved in Glucosinolate Accumulation During Root-Herbivory in Brassica rapa.

Abstract (Expand)

The optimal defense theory predicts that plants invest most energy in those tissues that have the highest value, but are most vulnerable to attacks. In Brassica species, root-herbivory leads to the … accumulation of glucosinolates (GSLs) in the taproot, the most valuable belowground plant organ. Accumulation of GSLs can result from local biosynthesis in response to herbivory. In addition, transport from distal tissues by specialized GSL transporter proteins can play a role as well. GSL biosynthesis and transport are both inducible, but the role these processes play in GSL accumulation during root-herbivory is not yet clear. To address this issue, we performed two time-series experiments to study the dynamics of transport and biosynthesis in local and distal tissues of Brassica rapa. We exposed roots of B. rapa to herbivory by the specialist root herbivore Delia radicum for 7 days. During this period, we sampled above- and belowground plant organs 12 h, 24 h, 3 days and 7 days after the start of herbivory. Next, we measured the quantity and composition of GSL profiles together with the expression of genes involved in GSL biosynthesis and transport. We found that both benzyl and indole GSLs accumulate in the taproot during root-herbivory, whereas we did not observe any changes in aliphatic GSL levels. The rise in indole GSL levels coincided with increased local expression of biosynthesis and transporter genes, which suggest that both biosynthesis and GSL transport play a role in the accumulation of GSLs during root herbivory. However, we did not observe a decrease in GSL levels in distal tissues. We therefore hypothesize that GSL transporters help to retain GSLs in the taproot during root-herbivory.

Authors: A. J. Touw, A. Verdecia Mogena, A. Maedicke, R. Sontowski, N. M. van Dam, T. Tsunoda

Date Published: 31st Jan 2020

Publication Type: Journal

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