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Horikiri S, Harada M, Asada R, Tsuchido T, Furuta M. Gamma-irradiated Aspergillus conidia show a growth curve with a reproductive death phase. JOURNAL OF RADIATION RESEARCH 2024; 65:28-35. [PMID: 37948456 PMCID: PMC10803171 DOI: 10.1093/jrr/rrad081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/09/2023] [Indexed: 11/12/2023]
Abstract
In this study, we evaluated the effects of gamma irradiation on the germination of Aspergillus conidia and mycelial growth using microscopy and predictive microbiological modeling methods. A dose of 0.4 kGy reduced the germination rate by 20% compared to the untreated control, indicating interphase death due to the high radiation dose. The number of colonies formed (5.5%) was lower than the germination rate (69%), suggesting that most colonies died after germination. Microscopic observations revealed that mycelial elongation ceased completely in the middle of the growth phase, indicating reproductive death. The growth curves of irradiated conidia exhibited a delayed change in the growth pattern, and a decrease in slope during the early stages of germination and growth at low densities. A modified logistic model, which is a general purpose growth model that allows for the evaluation of subpopulations, was used to fit the experimental growth curves. Dose-dependent waveform changes may reflect the dynamics of the subpopulations during germination and growth. These methods revealed the occurrence of two cell death populations resulting from gamma irradiation of fungal conidia and contribute to the understanding of irradiation-induced cell death in fungi.
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Affiliation(s)
- Shigetoshi Horikiri
- Department of Quantum and Radiation Engineering, Graduate School of Engineering, Osaka Prefecture University , 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Research Center of Microorganism Control, Organization for Research Promotion, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
| | - Mami Harada
- Department of Quantum and Radiation Engineering, Graduate School of Engineering, Osaka Prefecture University , 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
| | - Ryoko Asada
- Research Center of Microorganism Control, Organization for Research Promotion, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Department of Quantum and Radiation Engineering, Graduate School of Engineering, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Osaka International Research Center for Infectious Diseases, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
| | - Tetsuaki Tsuchido
- Research Center of Microorganism Control, Organization for Research Promotion, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
| | - Masakazu Furuta
- Research Center of Microorganism Control, Organization for Research Promotion, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Department of Quantum and Radiation Engineering, Graduate School of Engineering, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
- Osaka International Research Center for Infectious Diseases, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan
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Fang X, Zhao G, Dai J, Liu H, Wang P, Wang L, Song J, Zheng Z. Macro-morphological characterization and kinetics of Mortierella alpina colonies during batch cultivation. PLoS One 2018; 13:e0192803. [PMID: 30086137 PMCID: PMC6080745 DOI: 10.1371/journal.pone.0192803] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 01/30/2018] [Indexed: 11/19/2022] Open
Abstract
An effective method for research of macro-morphological characterization and its kinetics was developed by studying the macro-morphological characteristics of Mortierella alpina, an oleaginous zygomycete widely used to produce lipids rich in PUFA, in function of culture medium composition and to link morphological features of fungus with the level of lipid production. A number of distinct morphological forms including hollow pellets, fluffy pellets and freely dispersed mycelia were obtained by changing the fermentation factors. By fitting a Logistic curve, the maximum specific growth rate (μmax)was obtained, which determined the final mycelia morphology. μmax of 0.6584 in three kind of morphological forms is the more appropriate. According to the Luedeking-Piret equation fitting, α≠0 and β≠0, lipid production was partially associated with the hyphal growth, fluffy pellets which turn glucose into lipidwas more effective than the other two kinds of morphological forms.
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Affiliation(s)
- Xue Fang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
- University of Science and Technology of China, Hefei, China
| | - Genhai Zhao
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Jun Dai
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Hui Liu
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Peng Wang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Li Wang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Junying Song
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Zhiming Zheng
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Insitutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
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Novy V, Schmid M, Eibinger M, Petrasek Z, Nidetzky B. The micromorphology of Trichoderma reesei analyzed in cultivations on lactose and solid lignocellulosic substrate, and its relationship with cellulase production. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:169. [PMID: 27512503 PMCID: PMC4979124 DOI: 10.1186/s13068-016-0584-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 07/27/2016] [Indexed: 05/05/2023]
Abstract
BACKGROUND Trichoderma reesei is the principal producer of cellulolytic enzymes. Because of the strong influence on the enzyme production, the morphology of the filamentous fungi is a key parameter for process optimization. For cost-effective production of cellulolytic enzymes, the cultivation of T. reesei is performed on lignocellulosic waste streams. These insoluble substrates prevent the application of the conventional light microscopy for the analysis of fungal morphology. Here, we present a novel method for the micromorphological analysis based on confocal laser-scanning microscopy (CLSM) and the computer-aided image analysis. This method enabled the quantification of the dimensions of the single cell (intercalary length and cell width) and the degree of branching in cultivations on the industrially relevant substrates wheat straw and lactose. The micromorphology of two T. reesei strains, QM9414 and a carbon catabolite derepressed cre1 knockout mutant (Δcre1), was analyzed in dependence of substrate, inoculation method, and agitation velocity. RESULTS Trichoderma reesei strain Δcre1 formed shorter cells (10.09 µm) on average and developed more ramified mycelia (0.36 branches/cell) than strain QM9414 (12.03 µm, 0.22 branches/cell). Cultivated on wheat straw, the average cell length of QM9414 (10.87 µm) and Δcre1 (9.74 µm) was 10 and 21 % shorter as compared to reference cultivations on lactose. When inoculation was done with spores as compared to hyphal biomass, cell lengths of QM9414 (10.97 µm) and Δcre1 (9.10 µm) were on average about 20 % shorter. Strain performance was evaluated in protein concentration and total cellulase activity, which varied between 0.69 and 2.31 FPU/mL for Δcre1 and between 0.84 and 1.64 FPU/mL for QM9414. The cell length exhibited slightly negative correlation with the protein (regression coefficient -0.04 g/(L µm), R (2) 0.33) and the cellulase (-0.30 FPU/(mL µm), R (2) 0.53) production. CONCLUSIONS The dimensions of the single cell of T. reesei were dependent on strain background, substrate used and process conditions applied. Micromorphological changes were correlated semi-quantitatively with the efficiency of enzyme production. In providing a process analytical tool for enzyme production by T. reesei on lignocellulosic substrate, this study has relevance for the characterization and optimization of a critical step in the overall saccharification process.
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Affiliation(s)
- Vera Novy
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12/I, 8010 Graz, Austria
| | - Maximilian Schmid
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12/I, 8010 Graz, Austria
| | - Manuel Eibinger
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12/I, 8010 Graz, Austria
| | - Zdenek Petrasek
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12/I, 8010 Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12/I, 8010 Graz, Austria
- Austrian Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria
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Nitsche BM, Jørgensen TR, Akeroyd M, Meyer V, Ram AFJ. The carbon starvation response of Aspergillus niger during submerged cultivation: insights from the transcriptome and secretome. BMC Genomics 2012; 13:380. [PMID: 22873931 PMCID: PMC3527191 DOI: 10.1186/1471-2164-13-380] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 07/26/2012] [Indexed: 01/13/2023] Open
Abstract
Background Filamentous fungi are confronted with changes and limitations of their carbon source during growth in their natural habitats and during industrial applications. To survive life-threatening starvation conditions, carbon from endogenous resources becomes mobilized to fuel maintenance and self-propagation. Key to understand the underlying cellular processes is the system-wide analysis of fungal starvation responses in a temporal and spatial resolution. The knowledge deduced is important for the development of optimized industrial production processes. Results This study describes the physiological, morphological and genome-wide transcriptional changes caused by prolonged carbon starvation during submerged batch cultivation of the filamentous fungus Aspergillus niger. Bioreactor cultivation supported highly reproducible growth conditions and monitoring of physiological parameters. Changes in hyphal growth and morphology were analyzed at distinct cultivation phases using automated image analysis. The Affymetrix GeneChip platform was used to establish genome-wide transcriptional profiles for three selected time points during prolonged carbon starvation. Compared to the exponential growth transcriptome, about 50% (7,292) of all genes displayed differential gene expression during at least one of the starvation time points. Enrichment analysis of Gene Ontology, Pfam domain and KEGG pathway annotations uncovered autophagy and asexual reproduction as major global transcriptional trends. Induced transcription of genes encoding hydrolytic enzymes was accompanied by increased secretion of hydrolases including chitinases, glucanases, proteases and phospholipases as identified by mass spectrometry. Conclusions This study is the first system-wide analysis of the carbon starvation response in a filamentous fungus. Morphological, transcriptomic and secretomic analyses identified key events important for fungal survival and their chronology. The dataset obtained forms a comprehensive framework for further elucidation of the interrelation and interplay of the individual cellular events involved.
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Affiliation(s)
- Benjamin M Nitsche
- Institute of Biology Leiden, Molecular Microbiology and Biotechnology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands.
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BARRY D, WILLIAMS G. Microscopic characterisation of filamentous microbes: towards fully automated morphological quantification through image analysis. J Microsc 2011; 244:1-20. [DOI: 10.1111/j.1365-2818.2011.03506.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Vanzela APDFC, Said S, Prade RA. Phosphatidylinositol phospholipase C mediates carbon sensing and vegetative nuclear duplication rates in Aspergillus nidulans. Can J Microbiol 2011; 57:611-6. [DOI: 10.1139/w11-034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this work, we disrupted one of three putative phosphatidylinositol phospholipase C genes of Aspergillus nidulans and studied its effect on carbon source sensing linked to vegetative mitotic nuclear division. We showed that glucose does not affect nuclear division rates during early vegetative conidial germination (6–7 h) in either the wild type or the plcA-deficient mutant. Only after 8 h of cultivation on glucose did the mutant strain present some decrease in nuclear duplication. However, decreased nuclear division rates were observed in the wild type when cultivated in media amended with polypectate, whereas our plcA-deficient mutant did not show slow nuclear duplication rates when grown on this carbon source, even though it requires induction and secretion of multiple pectinolytic enzymes to be metabolized. Thus, plcA appears to be directly linked to high-molecular-weight carbon source sensing.
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Affiliation(s)
- Ana Paula de Figueiredo Conte Vanzela
- Laboratório de Enzimologia Industrial, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café S/No., Ribeirão Preto-SP 14040-903, Brazil
- Fungal Genetics Laboratory, Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Suraia Said
- Laboratório de Enzimologia Industrial, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café S/No., Ribeirão Preto-SP 14040-903, Brazil
| | - Rolf Alexander Prade
- Fungal Genetics Laboratory, Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
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Coumans JVF, Moens PDJ, Poljak A, Al-Jaaidi S, Pereg L, Raftery MJ. Plant-extract-induced changes in the proteome of the soil-borne pathogenic fungus Thielaviopsis basicola. Proteomics 2010; 10:1573-91. [PMID: 20186748 DOI: 10.1002/pmic.200900301] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Thielaviopsis basicola is a hemibiotroph fungus that causes black root rot disease in diverse plants with significant impact on cotton production in Australia. To elucidate how T. basicola growth and proteome are influenced by interactions with natural sources, this fungus was cultured in the presence of root extracts from non-host (wheat, hairy vetch) and susceptible host (cotton, lupin) plants. We found that T. basicola growth was significantly favored in the presence of host extracts, while hierarchical clustering analysis of 2-DE protein profiles of T. basicola showed plant species had a larger effect on the proteome than host/non-host status. Analysis by LC-MS/MS of unique and differentially expressed spots and identification using cross-species similarity searching and de novo sequencing allowed successful identification of 41 spots. These proteins were principally involved in primary metabolism with smaller numbers implicated in other diverse functions. Identification of several "morpho" proteins suggested morphological differences that were further microscopically investigated. Identification of several highly expressed spots suggested that vitamin B(6) is important in the T. basicola response to components present in hairy vetch extract, and finally, three spots, induced in the presence of lupin extract, may correspond to malic enzyme and be involved in lipid accumulation.
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Affiliation(s)
- Joëlle V F Coumans
- Molecular and Cellular Biology, School of Science and Technology, University of New England, Armidale, NSW, Australia.
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Role of phospholipase C and protein kinase C in Aspergillus nidulans during growth on pectin or glucose: Effects on germination and duplication cycle. Folia Microbiol (Praha) 2010; 55:228-32. [PMID: 20526834 DOI: 10.1007/s12223-010-0033-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 01/07/2010] [Indexed: 10/19/2022]
Abstract
The effects of PLC and Pkc inhibitors on Aspergillus nidulans depend on the carbon source. PLC inhibitors Spm and C48/80 delayed the first nuclear division in cultures growing on glucose, but stimulated it in media supplemented with pectin. Less intense were these effects on the mutant transformed with PLC-A gene rupture (AP27). Neomycin also delayed the germination in cultures growing on glucose or pectin; however, on glucose, the nuclear division was inhibited whereas in pectin it was stimulated. These effects were minor in AP27. The effects of Ro-31-8425 and BIM (both Pkc inhibitors) were also opposite for cultures growing on glucose or pectin. On glucose cultures of both strains BIM delayed germination and the first nuclear division, whereas on pectin both parameters were stimulated. Opposite effects were also detected when the cultures were growing on glucose or pectin in the presence of Ro-31-8425.
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Trutnau M, Suckale N, Groeger G, Bley T, Ondruschka J. Enhanced chitosan production and modeling hyphal growth of Mucor rouxii interpreting the dependence of chitosan yields on processing and cultivation time. Eng Life Sci 2009. [DOI: 10.1002/elsc.200900012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Ahamed A, Vermette P. Effect of culture medium composition on Trichoderma reesei's morphology and cellulase production. BIORESOURCE TECHNOLOGY 2009; 100:5979-87. [PMID: 19592237 DOI: 10.1016/j.biortech.2009.02.070] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 02/03/2009] [Accepted: 02/03/2009] [Indexed: 05/05/2023]
Abstract
The objective of this study was to determine how fungal morphology influences the volumetric cellulase productivity of Trichoderma reesei cultured in four media with lactose and lactobionic acid as fed-batch in a 7 L stirred tank bioreactor. The use of a cellulose-yeast extract culture medium yielded the highest enzyme production with a volumetric enzyme activity of 69.8 U L(-1) h(-1), and a maximum fungal biomass of 14.7 g L(-1). These findings were associated with the following morphological characteristics of the fungus: total mycelia was 98% of total mean projected area, mean hyphae length of 10 mm, mean hyphae volume of 45.1 mm(3), mean hyphae diameter of 7.9 microm, number of branches 9, and number of tips per hypha 29. A positive correlation was found between the total mycelia, the number of tips and the volumetric enzyme productivity, indicating the weight of these variables on the enzyme productivity.
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Affiliation(s)
- Aftab Ahamed
- Laboratoire de Bioingénierie et de Biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, 2500, Blvd de l'Université, Sherbrooke, Québec, Canada J1K 2R1
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Barry DJ, Chan C, Williams GA. Morphological quantification of filamentous fungal development using membrane immobilization and automatic image analysis. J Ind Microbiol Biotechnol 2009; 36:787-800. [PMID: 19277741 DOI: 10.1007/s10295-009-0552-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 02/17/2009] [Indexed: 10/21/2022]
Abstract
Mycelial morphology is a critically important process property in industrial fermentations of filamentous micro-organisms, as particular phenotypes are associated with maximum productivity. However, the accurate quantification of complex morphologies still represents a significant challenge in elucidating this relationship. A system has been developed for high-resolution characterisation of filamentous fungal growth on a solid substrate, using membrane immobilization and fully-automatic plug-ins developed for the public domain, Java-based, image-processing software, ImageJ. The system has been used to quantify the microscopic development of Aspergillus oryzae on malt agar, by measuring spore projected area and circularity, the total length of a hyphal element, the number of tips per element, and the hyphal growth unit. Two different stages of growth are described, from the swelling of a population of conidiospores up to fully developed, branched hyphae 24 h after inoculation. Spore swelling expressed as an increase in mean equivalent spore diameter was found to be approximately linear with time. Widespread germination of spores was observed by 8 h after inoculation. From approximately 12 h, the number of tips was found to increase exponentially. The specific growth rate of a population of hyphae was calculated as approximately 0.24-0.27 h(-1). A wide variation in growth kinetics was found within the population. The robustness of the image-analysis system was verified by testing the effect of small variations in the input data.
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Affiliation(s)
- David J Barry
- School of Biological Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland.
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Clemons KV, Stevens DA. Conventional or molecular measurement ofAspergillusload. Med Mycol 2009; 47 Suppl 1:S132-7. [DOI: 10.1080/13693780802213340] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Pollack JK, Li ZJ, Marten MR. Fungal mycelia show lag time before re-growth on endogenous carbon. Biotechnol Bioeng 2008; 100:458-65. [DOI: 10.1002/bit.21779] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Askolin S, Penttilä M, Wösten HAB, Nakari-Setälä T. TheTrichoderma reeseihydrophobin geneshfb1andhfb2have diverse functions in fungal development. FEMS Microbiol Lett 2005; 253:281-8. [PMID: 16243453 DOI: 10.1016/j.femsle.2005.09.047] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 09/26/2005] [Accepted: 09/28/2005] [Indexed: 10/25/2022] Open
Abstract
Hydrophobins are fungal self-assembling proteins. Here, the hydrophobin genes hfb1 and hfb2 were deleted in Trichoderma reesei and their biological roles studied. Our results suggest that HFBI has a role in hyphal development and HFBII in sporulation. Sporulating colonies of the Deltahfb2 strain were wettable and sporulation was only 50% of the parent strain. Colonies of Deltahfb1 showed wettable and fluffy phenotype. In shaken liquid cultures, the hyphae of Deltahfb1 were thinner and biomass formation was slower compared to the parent strain while in static liquid cultures no aerial hyphae were formed. Expressing the Schizophyllum commune hydrophobin SC3 in the Deltahfb1 strain restored the formation of aerial hyphae.
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Grimm LH, Kelly S, Krull R, Hempel DC. Morphology and productivity of filamentous fungi. Appl Microbiol Biotechnol 2005; 69:375-84. [PMID: 16317480 DOI: 10.1007/s00253-005-0213-5] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 10/06/2005] [Accepted: 10/10/2005] [Indexed: 10/25/2022]
Abstract
Cultivation processes involving filamentous fungi have been optimised for decades to obtain high product yields. Several bulk chemicals like citric acid and penicillin are produced this way. A simple adaptation of cultivation parameters for new production processes is not possible though. Models explaining the correlation between process-dependent growth behaviour and productivity are therefore necessary to prevent long-lasting empiric test series. Yet, filamentous growth consists of a complex microscopic differentiation process from conidia to hyphae resulting in various macroscopically visible appearances. Early approaches to model this morphologic development are recapitulated in this review to explain current trends in this area of research. Tailoring morphology by adjusting process parameters is one side of the coin, but an ideal morphology has not even been found. This article reviews several reasons for this fact starting with nutrient supply in a fungal culture and presents recent advances in the investigation of fungal metabolism. It illustrates the challenge to unfold the relationship between morphology and productivity.
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Affiliation(s)
- L H Grimm
- Institute of Biochemical Engineering, Technical University of Braunschweig, Gaussstrasse 17, 38106 Braunschweig, Germany
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Singh G, Imai J, Clemons KV, Stevens DA. Efficacy of caspofungin against central nervous system Aspergillus fumigatus infection in mice determined by TaqMan PCR and CFU methods. Antimicrob Agents Chemother 2005; 49:1369-76. [PMID: 15793114 PMCID: PMC1068651 DOI: 10.1128/aac.49.4.1369-1376.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have reported previously that prolonged caspofungin (CAS) dosing enhances survival in a murine model of central nervous system aspergillosis. In this study we determined by quantitative PCR (qPCR) and CFU enumeration whether CAS could reduce fungal burdens, prior to the deaths of untreated animals, and also assessed progressive infection in untreated mice. Mice were infected intracranially and treated for 4 days with CAS (1, 5, or 10 mg/kg of body weight/day) or amphotericin B (AMB) (3 mg/kg/day) starting 1 day postinfection. Fungal burdens in brains and kidneys of untreated controls were determined on days 1, 3, and 5 to assess progressive infection; burdens in treated animals were determined on day 5. qPCR showed higher burdens than CFU enumeration in all comparisons. In untreated animals, qPCR showed transiently increased burdens in brains, while CFU enumeration showed a decrease. qPCR showed increased burdens in kidneys, but CFU enumeration did not. Neither method indicated drug efficacy in the brain. Both methods showed AMB efficacy in the kidneys, and qPCR demonstrated CAS efficacy at all doses. Spearman correlations of qPCR and CFU determination results showed a significant correlation for most untreated groups; results correlated well for kidneys (P < or = 0.03) but not for brains in treated mice. Regression analyses of qPCR and CFU groups indicated different slopes for progressive infection in untreated animals but the same slopes for CAS dose-response efficacy. qPCR appeared to better reflect the progression of untreated infection. The lack of demonstration of efficacy in the brain suggests that longer dosing is necessary to cause burden reduction. These results also suggest that, when there is drug efficacy in a therapeutic study, either method appears to be useful for determining Aspergillus fumigatus burdens.
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Affiliation(s)
- Gaurav Singh
- California Institute for Medical Research, California, USA
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Model-based prediction of substrate conversion and protein synthesis and excretion in recombinant Aspergillus niger biopellets. Chem Eng Sci 2005. [DOI: 10.1016/j.ces.2004.12.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
The use of fungi for the production of commercial products is ancient, but it has increased rapidly over the last 50 years. Fungi are morphologically complex organisms, differing in structure at different times in their life cycle, differing in form between surface and submerged growth, differing also with the nature of the growth medium and physical environment. Many genes and physiological mechanisms are involved in the process of morphogenesis. In submerged culture, a large number of factors contribute to the development of any particular morphological form. Factors affecting morphology include the type and concentration of carbon substrate, levels of nitrogen and phosphate, trace minerals, dissolved oxygen and carbon dioxide, pH and temperature. Physical factors affecting morphology include fermenter geometry, agitation systems, rheology and the culture modes, whether batch, fed-batch or continuous. In many cases, particular morphological forms achieve maximum performance. It is a very difficult task to deduce unequivocal general relationships between process variables, product formation and fungal morphology since too many parameters influence these interrelationships and the role of many of them is still not fully understood. The use of automatic image analysis systems during the last decade proved an invaluable tool for characterizing complex mycelial morphologies, physiological states and relationships between morphology and productivity. Quantified morphological information can be used to build morphologically structured models of predictive value. The mathematical modeling of the growth and process performance has led to improved design and operation of mycelial fermentations and has improved the ability of scientists to translate laboratory observations into commercial practice. However, it is still necessary to develop improved and new experimental techniques for understanding phenomena such as the mechanisms of mycelial fragmentation and non-destructive measurement of concentration profiles in mycelial aggregates. This would allow the establishment of a process control on a physiological basis. This review is focused on the factors influencing the fungal morphology and metabolite production in submerged culture.
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Affiliation(s)
- Maria Papagianni
- Department of Hygiene and Technology of Food of Animal Origin, School of Veterinary Medicine, Aristotle University of Thessaloniki, 54006 Thessaloniki, Greece.
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19
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Abstract
Cytokinesis is the ultimate step of a cell cycle resulting in the generation of two progeny. Failure of correct cell division may be lethal for both, mother and daughter cells, and thus such a process must be tightly regulated with other events of the cell cycle. Differing solutions to the same problem have been developed in bacteria and plants while cytokinesis in animal and fungal cells is highly similar and requires a contractile ring containing actomyosin. Cytokinesis in fungi can be viewed as a three-stage process: (i) selection of a division site, (ii) orderly assembly of protein complexes, and finally (iii) dynamic events that lead to a constriction of the contractile ring and septum construction. Elaborate mechanisms known as the Mitotic Exit Network (MEN) and the Septation Initiation Network (SIN) have evolved to link these events, particularly the final steps of cytokinesis, with nuclear division. The purpose of this review was to discuss the latest developments in the fungal field and to describe the central known players required for key steps on the road to cell division. Differences in the cytokinesis of yeast-like fungi that result in complete cell separation in contrast to septation which leads to the compartmentalization of fungal hyphae are highlighted.
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Affiliation(s)
- Andrea Walther
- Department of Microbiology, Hans-Knöll Institute, Friedrich-Schiller University Jena, Winzerlaer, Germany
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20
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Lübbehüsen TL, Nielsen J, McIntyre M. Characterization of the Mucor circinelloides life cycle by on-line image analysis. J Appl Microbiol 2003; 95:1152-60. [PMID: 14633045 DOI: 10.1046/j.1365-2672.2003.02098.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The life cycle of the dimorphic fungus Mucor circinelloides was studied in a temperature-controlled flow-through cell, which constitutes an ideal tool when following the development of individual cells, with a view to understanding the growth and differentiation processes occurring in and between the different morphological forms of the organism. METHODS AND RESULTS Mycelial growth and the transformation of hyphae into chains of arthrospores were characterized by image analysis techniques and described quantitatively. The influence of the nature (glucose and xylose) and concentration of the carbon source on specific growth rate and hyphal growth unit length were studied. The organism branched more profusely on xylose than on glucose while the specific growth rates determined were rather similar. Methods were developed to study the yeast-like growth phase of M. circinelloides in the flow-through cell, and combined with fluorescent microscopy which allowed new insights to bud formation. Additionally, numbers and distribution of nuclei in arthrospores, hyphae and yeasts were studied. CONCLUSIONS The results give essential information on the morphological development of the organism. SIGNIFICANCE AND IMPACT OF STUDY Development of any industrial process utilizing this organism will be dependent on the information obtained here for effective process optimization.
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Affiliation(s)
- T L Lübbehüsen
- Center for Process Biotechnology, BioCentrum-DTU, Building 223, Technical University of Denmark, DK-2800 Lyngby, Denmark
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21
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Dynesen J, Nielsen J. Branching is coordinated with mitosis in growing hyphae of Aspergillus nidulans. Fungal Genet Biol 2003; 40:15-24. [PMID: 12948510 DOI: 10.1016/s1087-1845(03)00053-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Filamentous fungi like Aspergillus nidulans can effectively colonize their surroundings by the formation of new branches along the existing hyphae. While growth conditions, chemical perturbations, and mutations affecting branch formation have received great attention during the last decades, the mechanisms that regulates branching is still poorly understood. In this study, a possible relation between cell cycle progression and branching was studied by testing the effect of a nuclei distribution mutation, cell cycle inhibitors, and conditional cell cycle mutations in combination with tip-growth inhibitors and varying substrate concentrations on branch initiation. Formation of branches was blocked after inhibition of nuclear division, which was not caused by a reduced growth rate. In hyphae of a nuclei distribution mutant branching was severely reduced in anucleated hyphae whereas the number of branches per hyphal length was linearly correlated to the concentration of nuclei, in the nucleated hyphae. In wild type cells, branching intensity was increased when the tip extension was reduced, and reduced when growing on poor substrates. In these situations, the hyphal concentration of nuclei was maintained and it is suggested that branching is correlated to cell cycle progression in order to maintain a minimum required cytoplasmic volume per nucleus and to avoid the formation of anucleated hyphae in the absence of nuclear divisions. The presented results further suggest the hyphal diameter as a key point through which the hyphal element regulates its branching intensity in response to the surrounding substrate concentrations.
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Affiliation(s)
- Jens Dynesen
- Center for Process Biotechnology, Biocentrum-DTU, Building 223, Technical University of Denmark, Lyngby 2800, Denmark
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22
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Vanzela APDFC, Said S. Evidence for carbon source regulated protein kinase A and protein kinase C signaling in the duplication cycle, polarization and septum formation in Aspergillus nidulans. Microbiol Res 2003; 157:239-47. [PMID: 12398295 DOI: 10.1078/0944-5013-00156] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The effects of glucose and of a pectic substrate in the duplication cycle, spore polarization and septation of Aspergillus nidulans were tested in poor and rich media. Growth on poor conditions and on sodium polypectate slowed nuclear duplication and reduced the coupling of polarization to mitosis. Coupling of septation to the third mitosis was also reduced by changing growth conditions. When protein kinase A (PKA) and protein kinase C (PKC) activators were added to the media the results suggested a role for PKA in slowing the duplication cycle, while allowing polarization. Addition of a PKC activator to poor media uncoupled the first septum formation from the third mitosis in a carbon source-regulated manner, suggesting a role for PKC in coordinating cell cycle signals, growth and cytokinesis.
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Müller C, Hjort CM, Hansen K, Nielsen J. Altering the expression of two chitin synthase genes differentially affects the growth and morphology of Aspergillus oryzae. MICROBIOLOGY (READING, ENGLAND) 2002; 148:4025-4033. [PMID: 12480906 DOI: 10.1099/00221287-148-12-4025] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In Aspergillus oryzae, one full-length chitin synthase (chsB) and fragments of two other chitin synthases (csmA and chsC) were identified. The deduced amino acid sequence of chsB was similar (87% identity) to chsB from Aspergillus nidulans, which encodes a class III chitin synthase. The sequence obtained for csmA indicated that it had high similarity to class V chitin synthases. chsB and csmA disruption strains and a strain in which chsB transcription was controlled were constructed using the nitrite reductase (niiA) promoter. The strains were examined during hyphal growth by Northern analysis, analysis of the cell-wall composition and growth in the presence of Calcofluor white (CFW). The chsB disrupted strain and the uninduced p(niiA)-chsB strain exhibited hyperbranching, they had a lower level of conidiation than the wild-type and were sensitive to CFW at 50 mg l(-1). When chsB transcription was induced in the strain containing the p(niiA)-chsB construct, the strain displayed wild-type morphology on solid medium and at sub-maximum growth rates but the wild-type morphology was not fully restored during rapid growth in batch cultivation. The csmA disruption strain displayed morphological abnormalities, such as ballooning cells, intrahyphal hyphae and conidial scars. The growth was severely inhibited in the presence of 10 mg CFW l(-1). In none of the constructed strains did the cell-wall composition differ from the wild-type. Northern analysis indicated no change in the transcription of the chitin synthase genes csmA and chsC when chsB expression was altered, and there was no change in the transcription of chsB and chsC when csmA was disrupted.
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Affiliation(s)
- Christian Müller
- Center for Process Biotechnology, BioCentrum-DTU building, 223, Søltofts Plads, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark1
| | | | | | - Jens Nielsen
- Center for Process Biotechnology, BioCentrum-DTU building, 223, Søltofts Plads, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark1
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24
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Müller C, McIntyre M, Hansen K, Nielsen J. Metabolic engineering of the morphology of Aspergillus oryzae by altering chitin synthesis. Appl Environ Microbiol 2002; 68:1827-36. [PMID: 11916702 PMCID: PMC123896 DOI: 10.1128/aem.68.4.1827-1836.2002] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2001] [Accepted: 01/14/2002] [Indexed: 11/20/2022] Open
Abstract
Morphology and alpha-amylase production during submerged cultivation were examined in a wild-type strain (A1560) and in strains of Aspergillus oryzae in which chitin synthase B (chsB) and chitin synthesis myosin A (csmA) have been disrupted (ChsB/G and CM101). In a flowthrough cell, the growth of submerged hyphal elements was studied online, making it possible to examine the growth kinetics of the three strains. The average tip extension rates of the CM101 and ChsB/G strains were 25 and 88% lower, respectively, than that of the wild type. The branching intensity in the CM101 strain was 25% lower than that in the wild type, whereas that in the ChsB/G strain was 188% higher. During batch cultivation, inseparable clumps were formed in the wild-type strain, while no or fewer large inseparable clumps existed in the cultivations of the ChsB/G and CM101 strains. The alpha-amylase productivity was not significantly different in the three strains. A strain in which the transcription of chsB could be controlled by the nitrogen source-regulated promoter niiA (NiiA1) was examined during chemostat cultivation, and it was found that the branching intensity could be regulated by regulating the promoter, signifying an important role for chsB in branching. However, the pattern of branching responded very slowly to the change in transcription, and increased branching did not affect alpha-amylase productivity. alpha-Amylase residing in the cell wall was stained by immunofluorescence, and the relationship between tip number and enzyme secretion is discussed.
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Affiliation(s)
- Christian Müller
- Center for Process Biotechnology, BioCentrum-DTU, Technical University of Denmark, 2800 Kgs. Lyngby
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25
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McIntyre M, Müller C, Dynesen J, Nielsen J. Metabolic engineering of the morphology of Aspergillus. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2002; 73:103-28. [PMID: 11816809 DOI: 10.1007/3-540-45300-8_6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The morphology of filamentous organisms in submerged cultivation is a subject of considerable interest, notably due to the influence of morphology on process productivity. The relationship between process parameters and morphology is complex: the interactions between process variables, productivity, rheology, and macro- and micro-morphology create difficulties in defining and separating cause and effect. Additionally, organism physiology contributes a further level of complexity which means that the desired morphology (for optimum process performance and productivity) is likely to be process specific. However, a number of studies with increasingly powerful image analysis systems have yielded valuable information on what these desirable morphologies are likely to be. In parallel, studies on a variety of morphological mutants means that information on the genes involved in morphology is beginning to emerge. Indeed, we are now beginning to understand how morphology may be controlled at the molecular level. Coupling this knowledge with the tools of molecular biology means that it is now possible to design and engineer the morphology of organisms for specific bioprocesses. Tailor making strains with defined morphologies represents a clear advantage in optimization of submerged bioprocesses with filamentous organisms.
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Affiliation(s)
- M McIntyre
- Center for Process Biotechnology, Department of Biotechnology, Building 223, Technical University of Denmark, 2800 Lyngby, Denmark
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26
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McIntyre M, Dynesen J, Nielsen J. Morphological characterization of Aspergillus nidulans: growth, septation and fragmentation. MICROBIOLOGY (READING, ENGLAND) 2001; 147:239-46. [PMID: 11160817 DOI: 10.1099/00221287-147-1-239] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The influence of the sepA gene on the growth of Aspergillus nidulans has been investigated by characterizing and comparing the parental strain A28 (pabaA6 biA1) with the sepA null mutant (sepA4DeltaBM:). The sepA gene is known to affect the septation process in A. nidulans, therefore the sepA4DeltaBM: strain does not produce any septa during the first hours of growth. During batch cultivations sepA4DeltaBM: shows an abrupt decrease in specific growth rate and more pronounced fragmentation (in response to elevated stirrer speed) than the parental strain. Higher specific fragmentation rates (q(frag)) were obtained for the sepA4DeltaBM: strain. The physiological reasons for the differences have been investigated by employing fluorescent stains. Computerized image analysis revealed that the more pronounced fragmentation in the mutant was due to the lower number and irregular spacing of septa (visualized by calcofluor white staining), which resulted in a weaker hyphal structure that is more vulnerable to shear stress and fragmentation than the parental strain. This led to a loss of active biomass (determined by Mag fura staining) from the hyphae of the mutant, which had failed to compartmentalize by formation of septa, in turn resulting in decreased specific growth rates for the culture.
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Affiliation(s)
- M McIntyre
- Centre for Process Biotechnology, Department of Biotechnology, Building 223, Technical University of Denmark, 2800 Lyngby, Denmark
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