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Ulrich Kuck - One of the best experts on this subject based on the ideXlab platform.
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genome sequence and annotation of Acremonium chrysogenum producer of the β lactam antibiotic cephalosporin c
Genome Announcements, 2014Co-Authors: Dominik Terfehr, Tim A Dahlmann, Thomas Specht, Ivo Zadra, Hubert Kurnsteiner, Ulrich KuckAbstract:ABSTRACT The filamentous fungus Acremonium chrysogenum is the industrial producer of the β-lactam antibiotic cephalosporin C. Here, we present the genome sequence of strain ATCC 11550, which contains genes for 8,901 proteins, 127 tRNAs, and 22 rRNAs. Genome annotation led to the prediction of 42 gene clusters for secondary metabolites.
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tools for advanced and targeted genetic manipulation of the β lactam antibiotic producer Acremonium chrysogenum
Journal of Biotechnology, 2014Co-Authors: Sandra Bloemendal, Dominik Terfehr, D Loper, Katarina Kopke, Janina Kluge, Ines Teichert, Ulrich KuckAbstract:Acremonium chrysogenum is the major producer of the β-lactam antibiotic cephalosporin C and therefore of great importance for the pharmaceutical industry. However, this filamentous fungus is known to reproduce solely by asexual means, shows only sporadic conidiospore production, and has gradual fragmentation of the vegetative mycelium into arthrospores. Due to these peculiar growth characteristics and life style, strain improvement by recombinant technologies is much more challenging than for other biotechnologically relevant fungi. Here, we describe several molecular tools for genetic engineering of A. chrysogenum, including a ΔAcku70 deletion strain for homologous recombination. No physiological or morphological changes occurred due to deletion of the ku70 gene or integration of the nat1 cassette in this recipient strain. We also used a xylose-inducible promoter from Sordaria macrospora (Smxyl) to demonstrate induction of the gfp reporter gene in A. chrysogenum. The Smxyl promoter was used for construction of a vector molecule to develop a one-step FLP/FRT recombination system in A. chrysogenum. This system was then used in the ΔAcku70 deletion strain to construct a marker-free recipient strain for targeted DNA insertion into genomic DNA. The applicability of our tools was demonstrated by construction of a marker-free transgenic strain, lacking any foreign genes.
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asexual cephalosporin c producer Acremonium chrysogenum carries a functional mating type locus
Applied and Environmental Microbiology, 2008Co-Authors: Stefanie Poggeler, Birgit Hoff, Ulrich KuckAbstract:Acremonium chrysogenum, the fungal producer of the pharmaceutically relevant β-lactam antibiotic cephalosporin C, is classified as asexual because no direct observation of mating or meiosis has yet been reported. To assess the potential of A. chrysogenum for sexual reproduction, we screened an expressed sequence tag library from A. chrysogenum for the expression of mating type (MAT) genes, which are the key regulators of sexual reproduction. We identified two putative mating type genes that are homologues of the α-box domain gene, MAT1-1-1 and MAT1-1-2, encoding an HPG domain protein defined by the presence of the three invariant amino acids histidine, proline, and glycine. In addition, cDNAs encoding a putative pheromone receptor and pheromone-processing enzymes, as well as components of a pheromone response pathway, were found. Moreover, the entire A. chrysogenum MAT1-1 (AcMAT1-1) gene and regions flanking the MAT region were obtained from a genomic cosmid library, and sequence analysis revealed that in addition to AcMAT1-1-1 and AcMAT1-1-2, the AcMAT1-1 locus comprises a third mating type gene, AcMAT1-1-3, encoding a high-mobility-group domain protein. The α-box domain sequence of AcMAT1-1-1 was used to determine the phylogenetic relationships of A. chrysogenum to other ascomycetes. To determine the functionality of the AcMAT1-1 locus, the entire MAT locus was transferred into a MAT deletion strain of the heterothallic ascomycete Podospora anserina (the PaΔMAT strain). After fertilization with a P. anserina MAT1-2 (MAT+) strain, the corresponding transformants developed fruiting bodies with mature ascospores. Thus, the results of our functional analysis of the AcMAT1-1 locus provide strong evidence to hypothesize a sexual cycle in A. chrysogenum.
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Identification of a minimal cre1 promoter sequence promoting glucose-dependent gene expression in the β-lactam producer Acremonium chrysogenum
Current Genetics, 2008Co-Authors: Danielle Janus, Peter Hortschansky, Ulrich KuckAbstract:The promoter of the cre1 gene, encoding the glucose-dependent regulator CRE1 from the β-lactam producer Acremonium chrysogenum , carries 15 putative CRE1 binding sites (BS1 to BS15). For a detailed analysis, we fused cre1 promoter deletion derivatives with the DsRed reporter gene to perform a comparative gene expression analysis. Plate assays, Northern hybridizations, and spectrofluorometric measurements of DsRed identified the minimal D4 promoter sequence that promoted glucose-dependent expression. Truncated recombinant CRE1 interacted with D4 in electromobility shift analysis and these binding studies were further extended with two oligonucleotides, carrying putative CRE1 binding sites BS14 and BS15. Surface plasmon resonance analysis was performed using BS14 and BS15, along with four derivatives containing 2 or 4 bp substitutions within BS14 and BS15, respectively. Substitutions within BS14 abolished the high affinity interaction with CRE1, while mutations in BS15 only marginally diminished the affinity with CRE1. In vivo analysis of a modified D4 sequence with substitutions in the two binding sites confirmed the in vitro binding results and still promoted glucose-dependent gene expression. Our results will contribute to the construction of versatile expression vectors carrying a minimal cre1 promoter sequence that still confers glucose-dependent induction of gene expression.
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cpcr1 but not its interacting transcription factor acfkh1 controls fungal arthrospore formation in Acremonium chrysogenum
Molecular Microbiology, 2005Co-Authors: Birgit Hoff, Esther K Schmitt, Ulrich KuckAbstract:Fungal morphogenesis and secondary metabolism are frequently associated; however, the molecular determinants connecting both processes remain largely undefined. Here we demonstrate that CPCR1 (cephalosporin C regulator 1 from Acremonium chrysogenum), a member of the winged helix/regulator factor X (RFX) transcription factor family that regulates cephalosporin C biosynthesis, also controls morphological development in the beta-lactam producer A. chrysogenum. The use of a disruption strain, multicopy strains as well as several recombinant control strains revealed that CPCR1 is required for hyphal fragmentation, and thus the formation of arthrospores. In a DeltacpcR1 disruption strain that exhibits only hyphal growth, the wild-type cpcR1 gene was able to restore arthrospore formation; a phenomenon not observed for DeltacpcR1 derivatives or non-related genes. The intracellular expression of cpcR1, and control genes (pcbC, egfp) was determined by in vivo monitoring of fluorescent protein fusions. Further, the role of the forkhead transcription factor AcFKH1, which directly interacts with CPCR1, was studied by generating an Acfkh1 knockout strain. In contrast to CPCR1, AcFKH1 is not directly involved in the fragmentation of hyphae. Instead, the presence of AcFKH1 seems to be necessary for CPCR1 function in A. chrysogenum morphogenesis, as overexpression of a functional cpcR1 gene in a DeltaAcfkh1 background has no effect on arthrospore formation. Moreover, strains lacking Acfkh1 exhibit defects in cell separation, indicating an involvement of the forkhead transcription factor in mycelial growth of A. chrysogenum. Our data offer the potential to control fungal growth in biotechnical processes that require defined morphological stages for optimal production yields.
Gang Liu - One of the best experts on this subject based on the ideXlab platform.
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improvement of the crispr cas9 mediated gene disruption and large dna fragment deletion based on a chimeric promoter in Acremonium chrysogenum
Fungal Genetics and Biology, 2020Co-Authors: Chang Chen, Yuanyuan Pan, Jiajia Liu, Chengbao Duan, Gang LiuAbstract:Abstract Acremonium chrysogenum has been employed in the industrial production of cephalosporin C (CPC). However, there are still some impediments to understanding the regulation of CPC biosynthesis and improving strains due to the difficulty of genetic manipulation in A. chrysogenum, especially in the CPC high-producing strain C10. Here, an improved CRISPR-Cas9 system was constructed based on an U6/tRNA chimeric promoter. Using this system, high efficiency for single gene disruption was achieved in C10. In addition, double loci were simultaneously targeted when supplying with the homology-directed repair templates (donor DNAs). Based on this system, large DNA fragments up to 31.5 kb for the yellow compound sorbicillinoid biosynthesis were successfully deleted with high efficiency. Furthermore, CPC production was significantly enhanced when the sorbicillinoid biosynthetic genes were knocked out. This study provides a powerful tool for gene editing and strain improvement in A. chrysogenum.
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identification and characterization of an autophagy related gene acatg12 in Acremonium chrysogenum
Current Microbiology, 2019Co-Authors: Chang Chen, Wenyan Gao, Yanmin Wei, Gang LiuAbstract:Autophagy is a highly conserved mechanism to overcome various stresses and recycle cytoplasmic components and organelles. Ubiquitin-like (UBL) protein Atg12 is a key protein involved in autophagosome formation through stimulation of Atg8 conjugation to phosphatidylethanolamine. Here, we describe the identification of the autophagy-related gene Acatg12, encoding an Atg12 homologous protein in the cephalosporin C producing fungus Acremonium chrysogenum. Disruption of Acatg12 impaired the delivery and degradation of eGFP-Atg8, indicating that the autophagic process was blocked. Meanwhile, conidiation was dramatically reduced in the Acatg12 disruption mutant (∆Acatg12). In contrast, cephalosporin C production was increased twofold in ∆Acatg12, but fungal growth was reduced after 6 days fermentation. Consistent with these results, the transcriptional level of the cephalosporin biosynthetic genes was increased in ∆Acatg12. The results extend our understanding of autophagy in filamentous fungi.
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enhancing the production of cephalosporin c through modulating the autophagic process of Acremonium chrysogenum
Microbial Cell Factories, 2018Co-Authors: Ying Wang, Yuanyuan Pan, Gang LiuAbstract:Background Autophagy is used for degradation of cellular components and nutrient recycling. Atg8 is one of the core proteins in autophagy and used as a marker for autophagic detection. However, the autophagy of filamentous fungi is poorly understood compared with that of Saccharomyces cerevisiae. Our previous study revealed that disruption of the autophagy related gene Acatg1 significantly enhanced cephalosporin C yield through reducing degradation of cephalosporin biosynthetic proteins in Acremonium chrysogenum, suggesting that modulation of autophagic process is one promising way to increase antibiotic production in A. chrysogenum.
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a myb transcription factor represses conidiation and cephalosporin c production in Acremonium chrysogenum
Fungal Genetics and Biology, 2018Co-Authors: Ying Wang, Yuanyuan Pan, Yanling Wang, Liangkun Long, Xiaoling Zhang, Gang LiuAbstract:Acremonium chrysogenum is the industrial producer of cephalosporin C (CPC). We isolated a mutant (AC554) from a T-DNA inserted mutant library of A. chrysogenum. AC554 exhibited a reduced conidiation and lack of CPC production. In consistent with it, the transcription of cephalosporin biosynthetic genes pcbC and cefEF was significantly decreased in AC554. Thermal asymmetric interlaced polymerase chain reaction (TAIL-PCR) was performed and sequence analysis indicated that a T-DNA was inserted upstream of an open reading frame (ORF) which was designated AcmybA. On the basis of sequence analysis, AcmybA encodes a Myb domain containing transcriptional factor. Observation of red fluorescent protein (RFP) tagged AcMybA showed that AcMybA is naturally located in the nucleus of A. chrysogenum. Transcriptional analysis demonstrated that the AcmybA transcription was increased in AC554. In contrast, the AcmybA deleted mutant (ΔAcmybA) overproduced conidia and CPC. To screen the targets of AcmybA, we sequenced and compared the transcriptome of ΔAcmybA, AC554 and the wild-type strain at different developmental stages. Twelve differentially expressed regulatory genes were identified. Taken together, our results indicate that AcMybA negatively regulates conidiation and CPC production in A. chrysogenum.
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metabolic engineering of Acremonium chrysogenum for improving cephalosporin c production independent of methionine stimulation
Microbial Cell Factories, 2018Co-Authors: Jiajia Liu, Yuanyuan Pan, Wenyan Gao, Gang LiuAbstract:Cephalosporin C (CPC) produced by Acremonium chrysogenum is one of the most important drugs for treatment of bacterial infectious diseases. As the major stimulant, methionine is widely used in the industrial production of CPC. In this study, we found methionine stimulated CPC production through enhancing the accumulation of endogenous S-adenosylmethionine (SAM). To overcome the methionine dependent stimulation of CPC production, the methionine cycle of A. chrysogenum was reconstructed by metabolic engineering. Three engineered strains were obtained by overexpressing the SAM synthetase gene AcsamS and the cystathionine-γ-lyase gene mecB, and disrupting a SAM dependent methyltransferase gene Acppm1, respectively. Overexpression of AcsamS resulted in fourfold increase of CPC production which reached to 129.7 µg/mL. Disruption of Acppm1 also increased CPC production (up to 135.5 µg/mL) through enhancing the accumulation of intracellular SAM. Finally, an optimum recombinant strain (Acppm1DM-mecBOE) was constructed through overexpressing mecB in the Acppm1 disruption mutant. In this strain, CPC production reached to the maximum value (142.7 µg/mL) which was 5.5-fold of the wild-type level and its improvement was totally independent of methionine stimulation. In this study, we constructed a recombinant strain in which the improvement of CPC production was totally independent of methionine stimulation. This work provides an economic route for improving CPC production in A. chrysogenum through metabolic engineering.
Levente Karaffa - One of the best experts on this subject based on the ideXlab platform.
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[TTK] Assessment of the metabolic activity of Acremonium chrysogenum using Acridine Orange
'Springer Science and Business Media LLC', 2020Co-Authors: Erzsebet Sandor, Levente Karaffa, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R.thomas, Sándor Erzsébet, Karaffa Levente élettan és Biotechnológia), Pócsi István, Szentirmai AttilaAbstract:A method is described for the assessment of the metabolic activity of the filamentous fungus Acremonium chrysogenum using the fluorescent dye Acridine Orange. Changes in metabolic activity are indicated by a reversible red-green shift in the colour of the dye, quantifiable by image analysis. A. chrysogenum mycelia exhibited an overwhelmingly green colour in circumstances leading to high substrate uptake, while under carbon starvation they appeared orange-red. It is believed these colour changes reflected changes in internal pH. The method provides a visual tool for the investigation of the metabolic behaviour of filamentous fungi
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Regulation of the Cyanide-Resistant Alternative Respiratory Pathway in the Fungus Acremonium chrysogenum
University of Zagreb, 2003Co-Authors: Erzsebet Sandor, Erzsébet Fekete, Levente KaraffaAbstract:This review summarises the current knowledge on the biochemical and physiological events that directly or indirectly alter the engagement of the cyanide-resistant alternative respiratory pathway in the cephalosporin C producer filamentous fungus Acremonium chrysogenum. Particular emphasis is placed on the role this activity plays in the overproduction of antibiotic, and also on the critical fermentation technology background that supports its operation
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analysis of the relationship between growth cephalosporin c production and fragmentation in Acremonium chrysogenum
Canadian Journal of Microbiology, 2001Co-Authors: Erzsebet Sandor, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R Thomas, Levente KaraffaAbstract:Mycelial fragmentation in submerged cultures of the cephalosporin C (CPC) producing fungus Acremonium chrysogenum was characterized by image analysis. In both fed-batch and chemostat cultures, the ...
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analysis of the relationship between growth cephalosporin c production and fragmentation in Acremonium chrysogenum
Canadian Journal of Microbiology, 2001Co-Authors: Erzsebet Sandor, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R Thomas, Levente KaraffaAbstract:Mycelial fragmentation in submerged cultures of the cephalosporin C (CPC) producing fungus Acremonium chrysogenum was characterized by image analysis. In both fed-batch and chemostat cultures, the proportion of mycelial clumps seemed to be the most sensitive morphological indicator of fragmentation. In a fed-batch fermentation culture, this declined from roughly 60% at inoculation to less than 10% after 43 h. Subsequent additions of glucose resulted in a sharp increase back to near the initial value, an increase that reversed itself a few hours after glucose exhaustion. Meanwhile CPC production continued to decline steadily. On the other hand, the addition of soybean oil enhanced CPC production, but had no significant effect on the morphology. Although it may sometimes appear that morphology and productivity are related in batch or fed-batch cultures, this study suggests that this is because both respond simultaneously to more fundamental physiological changes, dependent on the availability of carbon. In ...
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cyanide resistant alternative respiration is strictly correlated to intracellular peroxide levels in Acremonium chrysogenum
Free Radical Research, 2001Co-Authors: Levente Karaffa, Erzsebet Sandor, Attila Szentirmai, Sándor Biró, Kalman Zoltan Vaczy, Imre PócsiAbstract:A strict correlation between the intensity of the cyanide-resistant alternative respiratory pathway and the intracellular peroxide levels in the cephalosporin C producer filamentous fungus Acremonium chrysogenum was demonstrated. Intracellular peroxide levels increased in a dose-dependent manner after addition of H2O2 to the culture media. A similar phenomenon was observed due to the specific inhibition of catalase by salicylic acid. In both cases, cyanide-resistant respiration was markedly stimulated. On the other hand, both cyanide-resistant respiration and intracellular peroxide levels were effectively suppressed by the lipid peroxyl radical scavenger DL-α-tocopherol, which breaks lipid peroxidation chains effectively. Our findings firmly supported the assumption that there is a connection between the intracellular peroxide levels and the intensity of the alternative respiratory pathway in fungi.
Erzsebet Sandor - One of the best experts on this subject based on the ideXlab platform.
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[TTK] Assessment of the metabolic activity of Acremonium chrysogenum using Acridine Orange
'Springer Science and Business Media LLC', 2020Co-Authors: Erzsebet Sandor, Levente Karaffa, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R.thomas, Sándor Erzsébet, Karaffa Levente élettan és Biotechnológia), Pócsi István, Szentirmai AttilaAbstract:A method is described for the assessment of the metabolic activity of the filamentous fungus Acremonium chrysogenum using the fluorescent dye Acridine Orange. Changes in metabolic activity are indicated by a reversible red-green shift in the colour of the dye, quantifiable by image analysis. A. chrysogenum mycelia exhibited an overwhelmingly green colour in circumstances leading to high substrate uptake, while under carbon starvation they appeared orange-red. It is believed these colour changes reflected changes in internal pH. The method provides a visual tool for the investigation of the metabolic behaviour of filamentous fungi
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Regulation of the Cyanide-Resistant Alternative Respiratory Pathway in the Fungus Acremonium chrysogenum
University of Zagreb, 2003Co-Authors: Erzsebet Sandor, Erzsébet Fekete, Levente KaraffaAbstract:This review summarises the current knowledge on the biochemical and physiological events that directly or indirectly alter the engagement of the cyanide-resistant alternative respiratory pathway in the cephalosporin C producer filamentous fungus Acremonium chrysogenum. Particular emphasis is placed on the role this activity plays in the overproduction of antibiotic, and also on the critical fermentation technology background that supports its operation
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glutathione metabolism of Acremonium chrysogenum in relation to cephalosporin c production is gamma glutamyltransferase in the center
Folia Microbiologica, 2003Co-Authors: Marta Nagy, Erzsebet Sandor, Erzsébet Fekete, Tamas Emri, Jeanyves Springael, Michel Penninckx, Imre PócsiAbstract:Methionine increased the intracellular glutathione (reduced) (GSH) pool and the specific gamma-glutamyltransferase (gamma-GT) activity in the cephalosporin C (CPC) producer Acremonium chrysogenum. The accelerated turnover of GSH might be indicative of the existence of a functioning gamma-glutamate cycle, and might supply the CPC biosynthetic machinery with L-cysteine. The gamma-GT was not subject to nitrogen metabolic repression but was more active in cells exposed to different oxidative-stress-generating agents. Exogenous cysteine hindered both the uptake of methionine and the induction of gamma-GT, and was not beneficial for CPC production. There was no causal relationship between the redox status of the cells and the observed cell morphology.
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analysis of the relationship between growth cephalosporin c production and fragmentation in Acremonium chrysogenum
Canadian Journal of Microbiology, 2001Co-Authors: Erzsebet Sandor, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R Thomas, Levente KaraffaAbstract:Mycelial fragmentation in submerged cultures of the cephalosporin C (CPC) producing fungus Acremonium chrysogenum was characterized by image analysis. In both fed-batch and chemostat cultures, the ...
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analysis of the relationship between growth cephalosporin c production and fragmentation in Acremonium chrysogenum
Canadian Journal of Microbiology, 2001Co-Authors: Erzsebet Sandor, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R Thomas, Levente KaraffaAbstract:Mycelial fragmentation in submerged cultures of the cephalosporin C (CPC) producing fungus Acremonium chrysogenum was characterized by image analysis. In both fed-batch and chemostat cultures, the proportion of mycelial clumps seemed to be the most sensitive morphological indicator of fragmentation. In a fed-batch fermentation culture, this declined from roughly 60% at inoculation to less than 10% after 43 h. Subsequent additions of glucose resulted in a sharp increase back to near the initial value, an increase that reversed itself a few hours after glucose exhaustion. Meanwhile CPC production continued to decline steadily. On the other hand, the addition of soybean oil enhanced CPC production, but had no significant effect on the morphology. Although it may sometimes appear that morphology and productivity are related in batch or fed-batch cultures, this study suggests that this is because both respond simultaneously to more fundamental physiological changes, dependent on the availability of carbon. In ...
Attila Szentirmai - One of the best experts on this subject based on the ideXlab platform.
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[TTK] Assessment of the metabolic activity of Acremonium chrysogenum using Acridine Orange
'Springer Science and Business Media LLC', 2020Co-Authors: Erzsebet Sandor, Levente Karaffa, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R.thomas, Sándor Erzsébet, Karaffa Levente élettan és Biotechnológia), Pócsi István, Szentirmai AttilaAbstract:A method is described for the assessment of the metabolic activity of the filamentous fungus Acremonium chrysogenum using the fluorescent dye Acridine Orange. Changes in metabolic activity are indicated by a reversible red-green shift in the colour of the dye, quantifiable by image analysis. A. chrysogenum mycelia exhibited an overwhelmingly green colour in circumstances leading to high substrate uptake, while under carbon starvation they appeared orange-red. It is believed these colour changes reflected changes in internal pH. The method provides a visual tool for the investigation of the metabolic behaviour of filamentous fungi
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analysis of the relationship between growth cephalosporin c production and fragmentation in Acremonium chrysogenum
Canadian Journal of Microbiology, 2001Co-Authors: Erzsebet Sandor, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R Thomas, Levente KaraffaAbstract:Mycelial fragmentation in submerged cultures of the cephalosporin C (CPC) producing fungus Acremonium chrysogenum was characterized by image analysis. In both fed-batch and chemostat cultures, the ...
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analysis of the relationship between growth cephalosporin c production and fragmentation in Acremonium chrysogenum
Canadian Journal of Microbiology, 2001Co-Authors: Erzsebet Sandor, Attila Szentirmai, Imre Pócsi, Gopal C Paul, Colin R Thomas, Levente KaraffaAbstract:Mycelial fragmentation in submerged cultures of the cephalosporin C (CPC) producing fungus Acremonium chrysogenum was characterized by image analysis. In both fed-batch and chemostat cultures, the proportion of mycelial clumps seemed to be the most sensitive morphological indicator of fragmentation. In a fed-batch fermentation culture, this declined from roughly 60% at inoculation to less than 10% after 43 h. Subsequent additions of glucose resulted in a sharp increase back to near the initial value, an increase that reversed itself a few hours after glucose exhaustion. Meanwhile CPC production continued to decline steadily. On the other hand, the addition of soybean oil enhanced CPC production, but had no significant effect on the morphology. Although it may sometimes appear that morphology and productivity are related in batch or fed-batch cultures, this study suggests that this is because both respond simultaneously to more fundamental physiological changes, dependent on the availability of carbon. In ...
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cyanide resistant alternative respiration is strictly correlated to intracellular peroxide levels in Acremonium chrysogenum
Free Radical Research, 2001Co-Authors: Levente Karaffa, Erzsebet Sandor, Attila Szentirmai, Sándor Biró, Kalman Zoltan Vaczy, Imre PócsiAbstract:A strict correlation between the intensity of the cyanide-resistant alternative respiratory pathway and the intracellular peroxide levels in the cephalosporin C producer filamentous fungus Acremonium chrysogenum was demonstrated. Intracellular peroxide levels increased in a dose-dependent manner after addition of H2O2 to the culture media. A similar phenomenon was observed due to the specific inhibition of catalase by salicylic acid. In both cases, cyanide-resistant respiration was markedly stimulated. On the other hand, both cyanide-resistant respiration and intracellular peroxide levels were effectively suppressed by the lipid peroxyl radical scavenger DL-α-tocopherol, which breaks lipid peroxidation chains effectively. Our findings firmly supported the assumption that there is a connection between the intracellular peroxide levels and the intensity of the alternative respiratory pathway in fungi.
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Assessment of the metabolic activity of Acremonium chrysogenum using Acridine Orange
Biotechnology Letters, 2000Co-Authors: Erzsebet Sandor, Levente Karaffa, Imre Pócsi, Gopal C Paul, Colin R Thomas, Attila SzentirmaiAbstract:A method is described for the assessment of the metabolic activity of the filamentous fungus Acremonium chrysogenum using the fluorescent dye Acridine Orange. Changes in metabolic activity are indicated by a reversible red-green shift in the colour of the dye, quantifiable by image analysis. A. chrysogenum mycelia exhibited an overwhelmingly green colour in circumstances leading to high substrate uptake, while under carbon starvation they appeared orange-red. It is believed these colour changes reflected changes in internal pH. The method provides a visual tool for the investigation of the metabolic behaviour of filamentous fungi.
