Aspergillus niger
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ABSTRACT:
PROVIDER: PRJNA147445 | ENA |
REPOSITORIES: ENA
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Project description:A. niger undergoes dramatic changes during asexual development. We tried to identify the differences in RNA expression levels that are important for this development. We used micro-arrays to determine which genes were up- or down-regulated in the aerial structures, the part of the colony that is formed during asexual development. A. niger was grown as a sandwiched culture (Wösten et al., 1991,Journal of General Microbiology 137: 2017–2023) in a 0.25 mm layer of 0.6 % agarose between two porous polycarbonate membranes (diameter 76 mm, pore size 0.1 µm; Profiltra; www.profiltra.nl). After six days of growth, the top membrane of the sandwich was replaced by a membrane with pores of 10 µm (Profiltra), allowing formation of aerial hyphae and conidiophores for 24 h. Vegetative mycelium and aerial structures of 7-day-old maltose-grown cultures of A. niger were harvested from 3 and 5 sandwiched colonies, respectively. The aerial structures were scraped from the top membrane of the sandwiched culture with a razor blade. From other colonies, vegetative mycelium was harvested by flipping over the top membrane and scraping it off with a razor blade.
2012-02-24 | E-GEOD-32123 | biostudies-arrayexpress
Project description:This work presents an exploration of submerged differentiation of the ubiquitous saprophyte and industrially important fungus, Aspergillus niger, in response to a limited availability of a sole carbon and energy source, maltose. In aspergilli and other mold fungi, asexual reproduction through formation of elaborate conidiogenic structures normally requires an aerial interface. This requirement is bypassed in submerged culture in response to severe nutrient limitation. Continuous cultures with cell retention (retentostat cultures) were applied to generate a fundamental physiological state, where the specific growth rate approaches zero, as the density of the cell population adapts to the supply of the limiting energy source. Temporal differentiation of mycelium structure and commitment to asexual reproduction were major phenomena, apparent on biochemical, morphological, physiological, and transcriptomic level. The severe substrate limitation had a rapid negative impact on cytoplasmic processes, and promoted endo- and exogenous nutrient mobilization, and hyphal compartmentalisation. The first conidiogenic structures appeared after one day with little additional differentiation until Day 4 to 6, where a transition to full commitment to reproductive growth took place. Submerged conidiation in A. niger involved transcriptional regulation of homologs of the regulatory pathway, centered around the Bristle gene (brlA), and structural genes previously described in other aspergilli. Comparison of transcriptomes, revealed a number of co-regulated gene clusters, which appear to encode secondary metabolite biosynthetic potential. We discuss the concept of maintenance energy in the context of differentiation, a possible physiological trigger for sporulation and the special physiological adaptations of the starved mycelium. We also present a simple and efficient method for in situ retention of filamentous organisms.
2010-07-07 | GSE21752 | GEO
Project description:This work presents an exploration of submerged differentiation of the ubiquitous saprophyte and industrially important fungus, Aspergillus niger, in response to a limited availability of a sole carbon and energy source, maltose. In aspergilli and other mold fungi, asexual reproduction through formation of elaborate conidiogenic structures normally requires an aerial interface. This requirement is bypassed in submerged culture in response to severe nutrient limitation. Continuous cultures with cell retention (retentostat cultures) were applied to generate a fundamental physiological state, where the specific growth rate approaches zero, as the density of the cell population adapts to the supply of the limiting energy source. Temporal differentiation of mycelium structure and commitment to asexual reproduction were major phenomena, apparent on biochemical, morphological, physiological, and transcriptomic level. The severe substrate limitation had a rapid negative impact on cytoplasmic processes, and promoted endo- and exogenous nutrient mobilization, and hyphal compartmentalisation. The first conidiogenic structures appeared after one day with little additional differentiation until Day 4 to 6, where a transition to full commitment to reproductive growth took place. Submerged conidiation in A. niger involved transcriptional regulation of homologs of the regulatory pathway, centered around the Bristle gene (brlA), and structural genes previously described in other aspergilli. Comparison of transcriptomes, revealed a number of co-regulated gene clusters, which appear to encode secondary metabolite biosynthetic potential. We discuss the concept of maintenance energy in the context of differentiation, a possible physiological trigger for sporulation and the special physiological adaptations of the starved mycelium. We also present a simple and efficient method for in situ retention of filamentous organisms. The dataset consists of 9 Affymetrix arrays derived from defined growth conditions of lab-scale bioreactor cultures (5L). Total RNA was extracted from biomass harvested at three different growth phases: exponential growth phase, 2 and 8 days of retentostat cultivation. For each of the phases, the data is derived from three biological replicates.
2010-07-07 | E-GEOD-21752 | biostudies-arrayexpress
Project description:A. niger undergoes dramatic changes during asexual development. We tried to identify the differences in RNA expression levels that are important for this development. We used micro-arrays to determine which genes were up- or down-regulated in the aerial structures, the part of the colony that is formed during asexual development.
2012-02-24 | GSE32123 | GEO
Project description:Conidia of Aspergillus niger are characterized by a dormant state and are moderate stress-resistant. Upon contact with a moist substrate, germination of conidia occurs by changing from a dormant stabilized state towards a growing vegetative cell. The RNA expression levels of dormant conidia and conidia that were in various stages of germination were studied. The RNA composition of dormant conidia was substantially different than all the subsequent stages of germination. This indicates that the distinct morphological changes that occur during germination are not correlated with the highest change in the transcriptome. Samples of germinating conidia of Aspergillus niger N402 were taken in triple at 0h (dormant), 2h, 4h, 6h and 8h after inoculation in CM.
2012-03-13 | E-GEOD-36439 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series: GSE37758: Aspergillus niger : Control (fructose) vs. steam-exploded sugarcane induction (SEB) GSE37760: Aspergillus niger : Control (fructose) vs. xylose + arabinose (XA) Refer to individual Series
2012-05-06 | E-GEOD-37795 | biostudies-arrayexpress
Project description:Colonies of Aspergillus niger secrete proteins throughout the colony except for the sporulating zone. Inactivation of flbA results in colonies that are unable to reproduce asexually and that secrete proteins throughout the mycelium. In addition, the ΔflbA strain shows cell lysis and has thinner cell walls. This pleiotropic phenotype is associated with differential expression of 38 transcription factor genes. Here, the impact of inactivation of one of these regulatory genes, fusR, was assessed. Mycelium of ΔfusR and its control strain MA234.1 was subjected to whole genome expression analysis, which revealed that 10 out of 15 genes of the fumonisin biosynthetic gene cluster were strongly downregulated in ΔfusR.
2018-02-21 | GSE93990 | GEO
Project description:Conidia of Aspergillus niger are characterized by a dormant state and are moderate stress-resistant. Upon contact with a moist substrate, germination of conidia occurs by changing from a dormant stabilized state towards a growing vegetative cell. The RNA expression levels of dormant conidia and conidia that were in various stages of germination were studied. The RNA composition of dormant conidia was substantially different than all the subsequent stages of germination. This indicates that the distinct morphological changes that occur during germination are not correlated with the highest change in the transcriptome.
2012-03-13 | GSE36439 | GEO
Project description:An Aspergillus niger colony can produce a few billion conidia. Formation of conidia producing conidiophores starts in the centre of the colony and moves outwards ending a few millimetres from the edge of the radial extending mycelium. As a result, the conidia within the colony centre are older than those in the intermediate and sub-peripheral zones. Here, it was assessed whether this results in heterogeneity of conidia within the colony. Conidia were harvested from conidiophores of cultures resulting from a confluent inoculated plate. A total number of 645-2421 genes were differentially expressed (fold change ≥ 2) when expression profiles of 2-, 5-, and 8-day-old conidia freshly harvested from conidiophores were compared. Genes without a PFAM or KEGG annotation were enriched in the up-regulated genes.
2017-01-01 | GSE83819 | GEO
Project description:Colonies of Aspergillus niger secrete proteins throughout the colony except for the sporulating zone. Strains in which the sporulation gene flbA is deleted do not reproduce asexually and secrete proteins throughout the mycelium. Moreover, ΔflbA hyphae lyse and have thinner cell walls. This pleiotropic phenotype is associated with differential expression of 36 transcription factor genes, of which msnB was inactivated in this study. Whole genome expression analysis of wild-type and ΔmsnB colonies showed differential expression of genes encoding secreted proteins, genes involved in the oxidoreductive balance, and in (secondary) metabolism. Biomass formation, sporulation, and the secretome in the medium were not affected in strain ΔmsnB. In contrast, ΔmsnB secreted more protein when compared to wild type. Taken together, msnB affects protein secretion and is a potential lead for improving A. niger as a cell factory.
2018-10-01 | GSE104669 | GEO