Project description:Aspergillus niger is well known for its capability to produce citrate in high amounts but the detailed metabolic response causing citrate production has not been fully elucidated. Manganese is known to have an important effect as its limitation is a requirement to obtain high-level citrate formation. To identify the translational regulation causing citric acid overflow metabolism, transcriptome and proteome data from cultivations in manganese limitation and manganese excess conditions were analyzed. In addition to four already described main responses, two novel events were identified. The first metabolic response was down regulation of phosphoenolpyruvate carboxykinase (PEPCK) during manganese limited conditions, which was confirmed by in vivo experiments. Down regulation of the first step in the gluconeogenesis, while maintaining a high activity through glycolysis, promoted secretion of citrate into the medium as an alternative regulatory mechanism for adjusting the intracellular concentrations of TCA intermediates. The other novel observation was down regulation of two cation transporters at manganese limited conditions. It was hypothesized that lowered cation transport across the mitochondrial membrane reduced the ability of the cell to maintain homeostasis thereby favoring citric acid secretion. Finally, upregulation of an ABC transporter was measured, which was assumed to be a citrate permease. 9 samples in total. Three conditions in triplicates
Project description:Aspergillus niger is well known for its capability to produce citrate in high amounts but the detailed metabolic response causing citrate production has not been fully elucidated. Manganese is known to have an important effect as its limitation is a requirement to obtain high-level citrate formation. To identify the translational regulation causing citric acid overflow metabolism, transcriptome and proteome data from cultivations in manganese limitation and manganese excess conditions were analyzed. In addition to four already described main responses, two novel events were identified. The first metabolic response was down regulation of phosphoenolpyruvate carboxykinase (PEPCK) during manganese limited conditions, which was confirmed by in vivo experiments. Down regulation of the first step in the gluconeogenesis, while maintaining a high activity through glycolysis, promoted secretion of citrate into the medium as an alternative regulatory mechanism for adjusting the intracellular concentrations of TCA intermediates. The other novel observation was down regulation of two cation transporters at manganese limited conditions. It was hypothesized that lowered cation transport across the mitochondrial membrane reduced the ability of the cell to maintain homeostasis thereby favoring citric acid secretion. Finally, upregulation of an ABC transporter was measured, which was assumed to be a citrate permease.
Project description:Oxygen limitation is regarded as a useful strategy to improve enzyme production by mycelial fungus like Aspergillus niger. However, the intracellular metabolic response of A. niger to oxygen limitation is still obscure. To address this, the metabolism of A. niger was studied using multi-omics integrated analysis based on the latest GEMs (genome-scale metabolic model), including metabolomics, fluxomics and transcriptomics. Upon sharp reduction of the oxygen supply, A. niger metabolism shifted to higher redox level status, as well as lower energy supply, characterized by the accumulation of intermediates from the TCA cycle, down-regulation of genes for fatty acid synthesis and a rapid decrease of the specific growth rate. The gene expression of the glyoxylate bypass was activated, consistent with the increasing flux, which was assumed to reduce the NADH formation from TCA cycle and benefit maintenance of the cellular redox balance under hypoxic conditions. In addition, the relative fluxes of the EMP pathway were increased, which possibly relieved the energy demand for cell metabolism.
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
Project description:The aim of this study was to investigate the regulatory role of Aspergillus niger AmyR and InuR during growth on inulin and sucrose
Project description:Expression data from batch cultivations of Aspergillus niger wild type strain ATCC 1015 and adrA, facB and creA deletion mutants constructed on ATCC 1015 background strain with glucose or glycerol as carbon sources. Genome-wide transcriptome analysis was used to identify genes either affected directly or indirectly by each transcription factor investigated during growth on a repressing or a derepressing carbon source. For this purpose, batch cultivations under well-controlled conditions were performed with Aspergillus niger wild type strain ATCC 1015 and the three deletion mutants of the corresponding transcription factors AdrA, FacB and CreA. Samples for RNA extraction were collected and further processed for hybridization in custom-designed Affymetrix microarrays containing probes for three Aspergillus species, including A. niger.
Project description:We report the genes regulated during citrate fermentation. Examination of 5 different time points during fermentation in Aspergillus niger H915-1.
Project description:Using transcriptomics, the strain-specific metabolism was mapped for two whole-genome sequenced strains of Aspergillus niger Keywords: Strain comparison