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Hung YHR, Chae M, Sauvageau D, Bressler DC. Adapted feeding strategies in fed-batch fermentation improve sugar delivery and ethanol productivity. Bioengineered 2023; 14:2250950. [PMID: 37655550 PMCID: PMC10478740 DOI: 10.1080/21655979.2023.2250950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/16/2023] [Accepted: 05/25/2023] [Indexed: 09/02/2023] Open
Abstract
Bioethanol is a renewable fuel widely used in road transportation and is generally regarded as a clean energy source. Although fermentation is one of the major processes in bioethanol production, studies on improving its efficiency through operational design are limited, especially compared to other steps (pretreatment and hydrolysis/saccharification). In this study, two adapted feeding strategies, in which feed medium addition (sugar delivery) was adjusted to increase the supply of fermentable sugar, were developed to improve ethanol productivity in 5-L fed-batch fermentation by Saccharomyces cerevisiae. Specifically, a linear adapted feeding strategy was established based on changes in cell biomass, and an exponential adapted feeding strategy was developed based on cell biomass accumulation. By implementing these two feeding strategies, the overall ethanol productivity reached 0.88± 0.04 and 0.87± 0.06 g/L/h, respectively. This corresponded to ~20% increases in ethanol productivity compared to fixed pulsed feeding operations. Additionally, there was no residual glucose at the end of fermentation, and final ethanol content reached 95± 3 g/L under the linear adapted operation and 104± 3 g/L under the exponential adapted feeding strategy. No statistical difference was observed in the overall ethanol yield (ethanol-to-sugar ratio) between fixed and adapted feeding strategies (~91%). These results demonstrate that sugar delivery controlled by adapted feeding strategies was more efficient than fixed feeding operations, leading to higher ethanol productivity. Overall, this study provides novel adapted feeding strategies to improve sugar delivery and ethanol productivity. Integration into the current practices of the ethanol industry could improve productivity and reduce production costs of fermentation processes.
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Affiliation(s)
- Yueh-Hao Ronny Hung
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Michael Chae
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Dominic Sauvageau
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - David C. Bressler
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
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2
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Adsul MG, Dixit P, Saini JK, Gupta RP, Ramakumar SSV, Mathur AS. Morphologically favorable mutant of Trichoderma reesei for low viscosity cellulase production. Biotechnol Bioeng 2022; 119:2167-2181. [PMID: 35470437 DOI: 10.1002/bit.28121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/22/2022] [Indexed: 11/07/2022]
Abstract
Metabolite production by filamentous fungi hampered because of high viscosity generated during growth. Low viscosity fermentation by mold is one of the preferred ways of large scale enzymes production. Cellulolytic enzymes play a key role during the process of lignocellulosic biomass conversion. In this study a mutant RC-23-1 was isolated through mutagenesis (diethyl sulfate followed by UV) of T. reesei RUT-C30. RC-23-1 not only gave higher cellulase production but also generated lower viscosity during enzyme production. Viscosity of mutant growth was more than three times lower than parent strain. RC-23-1 shows unique, yeast like colony morphology on solid media and small pellet like growth in liquid media. This mutant did not spread like mold on solid media. This mutant produces cellulases constitutively when grown in sugars. Using only glucose, the cellulase production was 4.1 FPU/ml. Among polysaccharides (avicel, xylan and pectin), avicel gave maximum of 6.2 FPU/ml and pretreated biomass (rice straw, wheat straw and sugarcane bagasse) produced 5.1-5.8 FPU/ml. At 7L scale reactor, fed-batch process was designed for cellulase production using different carbon and nitrogen sources. Maximum yield of cellulases was 182 FPU/g of lactose consumed was observed in fed-batch process. The produced enzyme used for hydrolysis of acid pretreated rice straw (20% solid loading) and maximum of 60 % glucan conversion was observed. RC-23-1 mutant is good candidate for large scale cellulase production and could be a model strain to study mold to yeast-like transformation. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Mukund G Adsul
- DBT-IOC Centre for Advanced Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad, 121007, India
| | - Pooja Dixit
- DBT-IOC Centre for Advanced Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad, 121007, India
| | - Jitendra K Saini
- DBT-IOC Centre for Advanced Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad, 121007, India
| | - Ravi P Gupta
- DBT-IOC Centre for Advanced Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad, 121007, India
| | - S S V Ramakumar
- DBT-IOC Centre for Advanced Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad, 121007, India
| | - Anshu S Mathur
- DBT-IOC Centre for Advanced Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad, 121007, India
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3
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Maumela P, Rose S, van Rensburg E, Chimphango AFA, Görgens JF. Bioprocess Optimisation for High Cell Density Endoinulinase Production from Recombinant Aspergillus niger. Appl Biochem Biotechnol 2021; 193:3271-3286. [PMID: 34117627 DOI: 10.1007/s12010-021-03592-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/28/2021] [Indexed: 10/21/2022]
Abstract
Endoinulinase gene was expressed in recombinant Aspergillus niger for selective and high-level expression using an exponential fed-batch fermentation. The effects of the growth rate (μ), glucose feed concentration, nitrogen concentration and fungal morphology on enzyme production were evaluated. A recombinant endoinulinase with a molecular weight of 66 kDa was secreted. Endoinulinase production was growth associated at μ> 0.04 h-1, which is characteristic of the constitutive gpd promoter used for the enzyme production. The highest volumetric activity (670 U/ml) was achieved at a growth rate of 93% of μmax (0.07 h-1), while enzyme activity (506 U/ml) and biomass substrate yield (0.043 gbiomassDW/gglucose) significantly decreased at low μ (0.04 h-1). Increasing the feed concentration resulted in high biomass concentrations and viscosity, which necessitated high agitation to enhance the mixing efficiency and oxygen. However, the high agitation and low DO levels (ca. 8% of saturation) led to pellet disruption and growth in dispersed morphology. Enzyme production profiles, product (Yp/s) and biomass (Yx/s) yield coefficients were not affected by feed concentration and morphological change. The gradual increase in the concentration of nitrogen sources showed that, a nitrogen limited culture was not suitable for endoinulinase production in recombinant A. niger. Moreover, the increase in enzyme volumetric activity was still directly related to an increase in biomass concentration. An increase in nitrogen concentration, from 3.8 to 12 g/L, resulted in volumetric activity increase from 393 to 670 U/ml, but the Yp/s (10053 U/gglucose) and Yx/s (0.049 gbiomasDWs/gglucose) did not significantly change. The data demonstrated the potential of recombinant A. niger and high cell density fermentation for the development of large-scale endoinulinase production system.
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Affiliation(s)
- Pfariso Maumela
- Department of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Shaunita Rose
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Eugéne van Rensburg
- Department of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
| | | | - Johann Ferdinand Görgens
- Department of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
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4
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Liu P, Wang S, Li C, Zhuang Y, Xia J, Noorman H. Dynamic response of Aspergillus niger to periodical glucose pulse stimuli in chemostat cultures. Biotechnol Bioeng 2021; 118:2265-2282. [PMID: 33666237 DOI: 10.1002/bit.27739] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 01/05/2021] [Accepted: 01/21/2021] [Indexed: 12/15/2022]
Abstract
In industrial large-scale bioreactors, microorganisms encounter heterogeneous substrate concentration conditions, which can impact growth or product formation. Here we carried out an extended (12 h) experiment of repeated glucose pulsing with a 10-min period to simulate fluctuating glucose concentrations with Aspergillus niger producing glucoamylase, and investigated its dynamic response by rapid sampling and quantitative metabolomics. The 10-min period represents worst-case conditions, as in industrial bioreactors the average cycling duration is usually in the order of 1 min. We found that cell growth and the glucoamylase productivity were not significantly affected, despite striking metabolomic dynamics. Periodical dynamic responses were found across all central carbon metabolism pathways, with different time scales, and the frequently reported ATP paradox was confirmed for this A. niger strain under the dynamic conditions. A thermodynamics analysis revealed that several reactions of the central carbon metabolism remained in equilibrium even under periodical dynamic conditions. The dynamic response profiles of the intracellular metabolites did not change during the pulse exposure, showing no significant adaptation of the strain to the more than 60 perturbation cycles applied. The apparent high tolerance of the glucoamylase producing A. niger strain for extreme variations in the glucose availability presents valuable information for the design of robust industrial microbial hosts.
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Affiliation(s)
- Peng Liu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Shuai Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Chao Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Yingping Zhuang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Jianye Xia
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Henk Noorman
- DSM Biotechnology Center, Delft, The Netherlands
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5
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Liu E, Segato F, Wilkins MR. Fed-batch production of Thermothelomyces thermophilus lignin peroxidase using a recombinant Aspergillus nidulans strain in stirred-tank bioreactor. BIORESOURCE TECHNOLOGY 2021; 325:124700. [PMID: 33461124 DOI: 10.1016/j.biortech.2021.124700] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Enzymatic lignin depolymerization is considered a favorable approach to utilize lignin due to the higher selectivity and less energy requirement when compared to thermochemical lignin valorization. Lignin peroxidase (LiP) is one of the key enzymes involved in lignin degradation and possesses high redox potential to oxidize non-phenolic structures and phenolic compounds in lignin. However, the production of LiP is mainly from white-rot fungi at small scales. It is critical to discover new LiP from other microorganisms and produce LiP at large scales. This study aims to produce a novel LiP originally from Thermothelomyces thermophiles using a recombinant Aspergillus nidulans strain. The LiP production medium was optimized, and different fed-batch strategies for LiP production were investigated to improve LiP activity, yield, and productivity. Results demonstrated that LiP production was enhanced by using multi-pulse fed-batch fermentation. A maximum LiP activity of 1,645 mU/L with a protein concentration of 0.26 g/L was achieved.
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Affiliation(s)
- Enshi Liu
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Fernando Segato
- Department of Biotechnology, University of São Paulo, Lorena, SP, Brazil
| | - Mark R Wilkins
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583, USA; Industrial Agricultural Products Center, University of Nebraska-Lincoln, Lincoln, NE 68583, USA; Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
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6
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Understanding gradients in industrial bioreactors. Biotechnol Adv 2020; 46:107660. [PMID: 33221379 DOI: 10.1016/j.biotechadv.2020.107660] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/22/2020] [Accepted: 11/14/2020] [Indexed: 01/07/2023]
Abstract
Gradients in industrial bioreactors have attracted substantial research attention since exposure to fluctuating environmental conditions has been shown to lead to changes in the metabolome, transcriptome as well as population heterogeneity in industrially relevant microorganisms. Such changes have also been found to impact key process parameters like the yield on substrate and the productivity. Hence, understanding gradients is important from both the academic and industrial perspectives. In this review the causes of gradients are outlined, along with their impact on microbial physiology. Quantifying the impact of gradients requires a detailed understanding of both fluid flow inside industrial equipment and microbial physiology. This review critically examines approaches used to investigate gradients including large-scale experimental work, computational methods and scale-down approaches. Avenues for future work have been highlighted, particularly the need for further coordinated development of both in silico and experimental tools which can be used to further the current understanding of gradients in industrial equipment.
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7
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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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8
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Wang G, Zhao J, Haringa C, Tang W, Xia J, Chu J, Zhuang Y, Zhang S, Deshmukh AT, van Gulik W, Heijnen JJ, Noorman HJ. Comparative performance of different scale-down simulators of substrate gradients in Penicillium chrysogenum cultures: the need of a biological systems response analysis. Microb Biotechnol 2018; 11:486-497. [PMID: 29333753 PMCID: PMC5902331 DOI: 10.1111/1751-7915.13046] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/18/2017] [Accepted: 12/18/2017] [Indexed: 12/22/2022] Open
Abstract
In a 54 m3 large‐scale penicillin fermentor, the cells experience substrate gradient cycles at the timescales of global mixing time about 20–40 s. Here, we used an intermittent feeding regime (IFR) and a two‐compartment reactor (TCR) to mimic these substrate gradients at laboratory‐scale continuous cultures. The IFR was applied to simulate substrate dynamics experienced by the cells at full scale at timescales of tens of seconds to minutes (30 s, 3 min and 6 min), while the TCR was designed to simulate substrate gradients at an applied mean residence time (τc) of 6 min. A biological systems analysis of the response of an industrial high‐yielding P. chrysogenum strain has been performed in these continuous cultures. Compared to an undisturbed continuous feeding regime in a single reactor, the penicillin productivity (qPenG) was reduced in all scale‐down simulators. The dynamic metabolomics data indicated that in the IFRs, the cells accumulated high levels of the central metabolites during the feast phase to actively cope with external substrate deprivation during the famine phase. In contrast, in the TCR system, the storage pool (e.g. mannitol and arabitol) constituted a large contribution of carbon supply in the non‐feed compartment. Further, transcript analysis revealed that all scale‐down simulators gave different expression levels of the glucose/hexose transporter genes and the penicillin gene clusters. The results showed that qPenG did not correlate well with exposure to the substrate regimes (excess, limitation and starvation), but there was a clear inverse relation between qPenG and the intracellular glucose level.
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Affiliation(s)
- Guan Wang
- State key laboratory of Bioreactor Engineering, East China University of Science and Technology (ECUST), Shanghai, China
| | - Junfei Zhao
- State key laboratory of Bioreactor Engineering, East China University of Science and Technology (ECUST), Shanghai, China
| | - Cees Haringa
- Transport Phenomena, Chemical Engineering Department, Delft University of Technology, Delft, The Netherlands
| | - Wenjun Tang
- State key laboratory of Bioreactor Engineering, East China University of Science and Technology (ECUST), Shanghai, China
| | - Jianye Xia
- State key laboratory of Bioreactor Engineering, East China University of Science and Technology (ECUST), Shanghai, China
| | - Ju Chu
- State key laboratory of Bioreactor Engineering, East China University of Science and Technology (ECUST), Shanghai, China
| | - Yingping Zhuang
- State key laboratory of Bioreactor Engineering, East China University of Science and Technology (ECUST), Shanghai, China
| | - Siliang Zhang
- State key laboratory of Bioreactor Engineering, East China University of Science and Technology (ECUST), Shanghai, China
| | | | - Walter van Gulik
- Cell Systems Engineering, Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Joseph J Heijnen
- Cell Systems Engineering, Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Henk J Noorman
- DSM Biotechnology Center, Delft, The Netherlands.,Bio Process Engineering, Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
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9
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Lee H, Lee YM, Heo YM, Hong JH, Jang S, Ahn BJ, Lee SS, Kim JJ. Optimization of Fungal Enzyme Production by Trichoderma harzianum KUC1716 through Surfactant-Induced Morphological Changes. MYCOBIOLOGY 2017; 45:48-51. [PMID: 28435355 PMCID: PMC5395501 DOI: 10.5941/myco.2017.45.1.48] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 11/30/2016] [Accepted: 01/04/2017] [Indexed: 06/07/2023]
Abstract
The morphological optimization of Trichoderma harzianum was carried out using several surfactants to achieve increased cellulase production. Addition of the surfactants to the culture medium successfully modified the fungal morphology from an aggregated form to a dispersed form. Optimization of the fungal morphology increased cellulase activity up to 177%. The morphologically optimized conditions enhanced the accessibility of the fungus to substrates and thus promoted cellulase production.
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Affiliation(s)
- Hanbyul Lee
- Division of Environmental Science & Ecological Engineering, College of Life Science & Biotechnology, Korea University, Seoul 02841, Korea
| | - Young Min Lee
- Division of Environmental Science & Ecological Engineering, College of Life Science & Biotechnology, Korea University, Seoul 02841, Korea
| | - Young Mok Heo
- Division of Environmental Science & Ecological Engineering, College of Life Science & Biotechnology, Korea University, Seoul 02841, Korea
| | - Joo-Hyun Hong
- Division of Environmental Science & Ecological Engineering, College of Life Science & Biotechnology, Korea University, Seoul 02841, Korea
| | - Seokyoon Jang
- Division of Environmental Science & Ecological Engineering, College of Life Science & Biotechnology, Korea University, Seoul 02841, Korea
| | - Byoung Jun Ahn
- Division of Wood Chemistry and Microbiology, National Institute of Forest Science, Seoul 02455, Korea
| | - Sung-Suk Lee
- Division of Wood Chemistry and Microbiology, National Institute of Forest Science, Seoul 02455, Korea
| | - Jae-Jin Kim
- Division of Environmental Science & Ecological Engineering, College of Life Science & Biotechnology, Korea University, Seoul 02841, Korea
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10
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11
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Lu H, Li C, Tang W, Wang Z, Xia J, Zhang S, Zhuang Y, Chu J, Noorman H. Dependence of fungal characteristics on seed morphology and shear stress in bioreactors. Bioprocess Biosyst Eng 2015; 38:917-28. [DOI: 10.1007/s00449-014-1337-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 12/07/2014] [Indexed: 11/30/2022]
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12
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Quintanilla D, Hagemann T, Hansen K, Gernaey KV. Fungal Morphology in Industrial Enzyme Production--Modelling and Monitoring. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2015; 149:29-54. [PMID: 25724310 DOI: 10.1007/10_2015_309] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Filamentous fungi are widely used in the biotechnology industry for the production of industrial enzymes. Thus, considerable work has been done with the purpose of characterizing these processes. The ultimate goal of these efforts is to be able to control and predict fermentation performance on the basis of "standardized" measurements in terms of morphology, rheology, viscosity, mass transfer and productivity. However, because the variables are connected or dependent on each other, this task is not trivial. The aim of this review article is to gather available information in order to explain the interconnectivity between the different variables in submerged fermentations. An additional factor which makes the characterization of a fermentation broth even more challenging is that the data obtained are also dependent on the way they have been collected-meaning which technologies or probes have been used, and on the way the data is interpreted-i.e. which models were applied. The main filamentous fungi used in industrial fermentation are introduced, ranging from Trichoderma reesei to Aspergillus species. Due to the fact that secondary metabolites, like antibiotics, are not to be considered bulk products, organisms like e.g. Penicillium chrysogenum are just briefly touched upon for the description of some characterization techniques. The potential for development of different morphological phenotypes is discussed as well, also in view of what this could mean to productivity and-equally important-the collection of the data. An overview of the state of the art techniques for morphology characterization is provided, discussing methods that finally can be employed as the computational power has grown sufficiently in the recent years. Image analysis (IA) clearly benefits most but it also means that methods like near infrared measurement (NIR), capacitance and on-line viscosity now provide potential alternatives as powerful tools for characterizing morphology. These measuring techniques, and to some extent their combination, allow obtaining the data necessary for supporting the creation of mathematical models describing the fermentation process. An important part of this article will indeed focus on describing the different models, and on discussing their importance to fermentations of filamentous fungi in general. The main conclusion is that it has not yet been attempted to develop an overarching model that spans across strains and scales, as most studies indeed conclude that their respective results might be strain specific and not necessarily valid across scales.
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Affiliation(s)
- Daniela Quintanilla
- Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Building 229, 2800, Lyngby, Denmark
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13
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Chen Y, Wang Z, Chu J, Zhuang Y, Zhang S, Yu X. Significant decrease of broth viscosity and glucose consumption in erythromycin fermentation by dynamic regulation of ammonium sulfate and phosphate. BIORESOURCE TECHNOLOGY 2013; 134:173-9. [PMID: 23500575 DOI: 10.1016/j.biortech.2013.02.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 02/08/2013] [Accepted: 02/09/2013] [Indexed: 06/01/2023]
Abstract
In this study, the effects of nitrogen sources on broth viscosity and glucose consumption in erythromycin fermentation were investigated. By controlling ammonium sulfate concentration, broth viscosity and glucose consumption were decreased by 18.2% and 61.6%, respectively, whereas erythromycin biosynthesis was little affected. Furthermore, erythromycin A production was increased by 8.7% still with characteristics of low broth viscosity and glucose consumption through the rational regulations of phosphate salt, soybean meal and ammonium sulfate. It was found that ammonium sulfate could effectively control proteinase activity, which was correlated with the utilization of soybean meal as well as cell growth. The pollets formation contributed much to the decrease of broth viscosity. The accumulation of extracellular propionate and succinate under the new regulation strategy indicated that higher propanol consumption might increase the concentration of methylmalonyl-CoA and propionyl-CoA and thus could increase the flux leading to erythromycin A.
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Affiliation(s)
- Yong Chen
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China
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14
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Motta FL, Santana MHA. Biomass production from Trichoderma viride in nonconventional oat medium. Biotechnol Prog 2012; 28:1245-50. [PMID: 22736524 DOI: 10.1002/btpr.1578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/15/2012] [Indexed: 11/06/2022]
Abstract
Oatmeal, an alternative, renewable, and low-cost substrate, was used for the production of Trichoderma viride spores by submerged fermentation. The nonconventional oat medium was only supplemented with potato peptone, which is a green source of nitrogen for the microorganism. Because particles are suspended in the nonconventional oat medium, the characterization was based on viscosity, average particle diameter, size distribution, and porosity of the particles. Because of the complexity of the fungal biomass extraction, the dry weight and protein content were used as methods for quantifying the growth of T. viride. The inversion between the proportion of mycelia and spores was captured in the microscopic image analysis during the fermentation process. After 60 h, spores began to appear, accounting for most of the form present at 120 h of fermentation. The decrease in pH and the increase in glucose concentration during fermentation indicate that glucan hydrolysis occurs and that glucose is released into the medium. The potential for industrial applications of submerged fermentation with oats for biomass production of T. viride is noted in the results. This simple and easily controllable process has several advantages, including the use of low-cost substrates for the propagation of a microorganism that is widely used in scientific and commercial settings.
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Affiliation(s)
- F L Motta
- Development of Biotechnological Processes Laboratory, Dept of Biotechnological Processes, University of Campinas, 13081-970 Campinas, SP, Brazil
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15
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Rønnest NP, Stocks SM, Lantz AE, Gernaey KV. Comparison of laser diffraction and image analysis for measurement of Streptomyces coelicolor cell clumps and pellets. Biotechnol Lett 2012; 34:1465-73. [PMID: 22538546 DOI: 10.1007/s10529-012-0936-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 04/17/2012] [Indexed: 10/28/2022]
Abstract
Morphology is important in industrial processes involving filamentous organisms because it affects the mixing and mass transfer and can be linked to productivity. Image analysis provides detailed information about the morphology but, in practice, it is often laborious including both collection of high quality images and image processing. Laser diffraction is rapid and fully automatic and provides a volume-weighted distribution of the particle sizes. However, it is based on a number of assumptions that do not always apply to samples. We have evaluated laser diffraction to measure cell clumps and pellets of Streptomyces coelicolor compare to image analysis. Samples, taken five times during fed-batch cultivation, were analyzed by image analysis and laser diffraction. The volume-weighted size distribution was calculated for each sample. Laser diffraction and image analysis yielded similar size distributions, i.e. unimodal or bimodal distributions. Both techniques produced similar estimations of the population means, whereas the estimates of the standard deviations were generally higher using laser diffraction compared to image analysis. Therefore, laser diffraction measurements are high quality and the technique may be useful when rapid measurements of filamentous cell clumps and pellets are required.
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Affiliation(s)
- Nanna Petersen Rønnest
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, 2800, Kgs. Lyngby, Denmark
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16
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Kim Y, Islam N, Moss BJ, Nandakumar MP, Marten MR. Autophagy induced by rapamycin and carbon-starvation have distinct proteome profiles in Aspergillus nidulans. Biotechnol Bioeng 2011; 108:2705-15. [DOI: 10.1002/bit.23223] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 04/06/2011] [Accepted: 05/09/2011] [Indexed: 11/09/2022]
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17
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Albaek MO, Gernaey KV, Hansen MS, Stocks SM. Modeling enzyme production with Aspergillus oryzae in pilot scale vessels with different agitation, aeration, and agitator types. Biotechnol Bioeng 2011; 108:1828-40. [DOI: 10.1002/bit.23121] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2010] [Revised: 02/16/2011] [Accepted: 02/22/2011] [Indexed: 11/06/2022]
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18
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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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19
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Junker B, Walker A, Hesse M, Lester M, Vesey D, Christensen J, Burgess B, Connors N. Pilot-scale process development and scale up for antifungal production. Bioprocess Biosyst Eng 2008; 32:443-58. [PMID: 18853195 DOI: 10.1007/s00449-008-0264-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 09/18/2008] [Indexed: 11/25/2022]
Abstract
A pilot-scale fermentation was developed for an antifungal compound produced by a filamentous fungus. Replacement of galactose with lactose (20-fold cost savings) and a threefold phosphate reduction (15 to 5 g/L) improved productivity 2.5-fold. Addition of supplements--glycine, cobalt chloride, and trace elements--resulted in a further twofold productivity increase, greater process robustness, and less foaming which reduced antifoam addition tenfold (30 to <3 mL/L). Mid-cycle lactose limitations were addressed by raising initial lactose levels (40 to 120 g/L) resulting in another twofold productivity increase. Overall, peak titers increased tenfold from 45 +/- 9 to 448 +/- 39 mg/L, and productivities improved from 3 to 25 mg/L day. Despite its high productivity, process scale up was challenged by high broth viscosity (5,000-6,000 cP at 16.8 s(-1)). Gassed power requirements at the 600 L scale (4.7 kW/1,000 L) exceeded available power at the 15,000 L scale (3.0 kW/1,000 L), and broth transfer to the downstream isolation facility was hindered. Mid-cycle broth dilution with up to five 10 vol% additions of 12 wt% lactose solution or whole medium-reduced viscosity three- to fivefold (1,000-1,500 cP at 16.8 s(-1)), gassed power within scale-up limits (2.5 kW/1,000 L), and peak titer by up to 45%. The process was scaled up to the 15,000 L working volume based on constant aeration rate (vvm) and peak impeller tip speed, raising superficial velocities at similar shear. This strategy maximized mass transfer rates at target gassed power per unit volume levels, and along with controlled broth viscosity, precluded multiple dilution additions. A final titer of 333 mg/L with one dilution addition was achieved, somewhat lower than expected, likely owing to inhibition from some unmeasured volatile compound (not believed to be carbon dioxide) during an extended period of high back-pressure in the early production phase.
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Affiliation(s)
- Beth Junker
- Fermentation Development and Operations, Merck Research Laboratories, Rahway, NJ, USA.
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20
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Feast or famine: autophagy control and engineering in eukaryotic cell culture. Curr Opin Biotechnol 2008; 19:518-26. [DOI: 10.1016/j.copbio.2008.07.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 07/25/2008] [Accepted: 07/29/2008] [Indexed: 12/15/2022]
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21
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Zhao L, Schaefer D, Xu H, Modi SJ, LaCourse WR, Marten MR. Elastic Properties of the Cell Wall of Aspergillus nidulans Studied with Atomic Force Microscopy. Biotechnol Prog 2008; 21:292-9. [PMID: 15903268 DOI: 10.1021/bp0497233] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Currently, little is known about the mechanical properties of filamentous fungal hyphae. To study this topic, atomic force microscopy (AFM) was used to measure cell wall mechanical properties of the model fungus Aspergillus nidulans. Wild type and a mutant strain (deltacsmA), lacking one of the chitin synthase genes, were grown in shake flasks. Hyphae were immobilized on polylysine-coated coverslips and AFM force--displacement curves were collected. When grown in complete medium, wild-type hyphae had a cell wall spring constant of 0.29 +/- 0.02 N/m. When wild-type and mutant hyphae were grown in the same medium with added KCl (0.6 M), hyphae were significantly less rigid with spring constants of 0.17 +/- 0.01 and 0.18 +/- 0.02 N/m, respectively. Electron microscopy was used to measure the cell wall thickness and hyphal radius. By use of finite element analysis (FEMLAB v 3.0, Burlington, MA) to simulate AFM indentation, the elastic modulus of wild-type hyphae grown in complete medium was determined to be 110 +/- 10 MPa. This decreased to 64 +/- 4 MPa for hyphae grown in 0.6 M KCl, implying growth medium osmotic conditions have significant effects on cell wall elasticity. Mutant hyphae grown in KCl-supplemented medium were found to have an elastic modulus of 67 +/- 6 MPa. These values are comparable with other microbial systems (e.g., yeast and bacteria). It was also found that under these growth conditions axial variation in elastic modulus along fungal hyphae was small. To determine the relationship between composition and mechanical properties, cell wall composition was measured by anion-exchange liquid chromatography and pulsed electrochemical detection. Results show similar composition between wild-type and mutant strains. Together, these data imply differences in mechanical properties may be dependent on varying molecular structure of hyphal cell walls as opposed to wall composition.
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Affiliation(s)
- Liming Zhao
- Department of Chemical and Biochemical Engineering, University of Maryland-Baltimore County, Baltimore, Maryland 21250, USA
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22
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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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23
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Fazenda ML, Seviour R, McNeil B, Harvey LM. Submerged Culture Fermentation of “Higher Fungi”: The Macrofungi. ADVANCES IN APPLIED MICROBIOLOGY 2008; 63:33-103. [DOI: 10.1016/s0065-2164(07)00002-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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Verma M, Brar SK, Tyagi R, Sahai V, Prévost D, Valéro J, Surampalli R. Bench-scale fermentation of Trichoderma viride on wastewater sludge: Rheology, lytic enzymes and biocontrol activity. Enzyme Microb Technol 2007. [DOI: 10.1016/j.enzmictec.2007.06.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Verma M, Brar SK, Tyagi RD, Surampalli RY, Valéro JR. Dissolved oxygen as principal parameter for conidia production of biocontrol fungi Trichoderma viride in non-Newtonian wastewater. J Ind Microbiol Biotechnol 2006; 33:941-52. [PMID: 16909264 DOI: 10.1007/s10295-006-0164-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Accepted: 07/23/2006] [Indexed: 10/24/2022]
Abstract
Dissolved oxygen (DO) concentration was selected as a principal parameter for translating results of shake flask fermentation of Trichoderma viride (biocontrol fungi) to a fermenter scale. All fermentations were carried out in a 7.5 l automated fermenter with a working volume of 4 l. Fermentation performance parameters such as volumetric oxygen transfer coefficient (k (L) a), oxygen uptake rate (OUR), rheology, conidia concentration, glucose consumption, soluble chemical oxygen demand, entomotoxicity and inhibition index were measured. The conidia concentration, entomotoxicity and inhibition index were either stable or improved at lower DO concentration (30%). Variation of OUR aided in assessing the oxygen supply capacity of the fermenter and biomass growth. Meanwhile, rheological profiles demonstrated the variability of wastewater during fermentation due to mycelial growth and conidiation. In order to estimate power consumption, the agitation and the aeration requirements were quantified in terms of area under the curves, agitation vs. time (rpm h), and aeration vs. time (lpm h). This simple and novel strategy of fermenter operation proved to be highly successful which can be adopted to other biocontrol fungi.
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Affiliation(s)
- M Verma
- INRS-ETE, Université du Québec, 490, de la Couronne, Quebéc, Canada G1K 9A9
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26
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Liu Y, Sha Q, Wu S, Wang J, Yang L, Sun W. Enzymatic resolution of racemic phenyloxirane by a novel epoxide hydrolase from Aspergillus niger SQ-6 and its fed-batch fermentation. J Ind Microbiol Biotechnol 2005; 33:274-82. [PMID: 16320035 DOI: 10.1007/s10295-005-0062-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Accepted: 10/27/2005] [Indexed: 10/25/2022]
Abstract
A microorganism with the ability to catalyze the resolution of racemic phenyloxirane was isolated and identified as Aspergillus niger SQ-6. Chiral capillary electrophoresis was successfully applied to separate both phenyloxirane and phenylethanediol. The epoxide hydrolase (EH) involved in this resolution process was (R)-stereospecific and constitutively expressed. When whole cells were used during the biotransformation process, the optimum temperature and pH for stereospecific vicinal diol production were 35 degrees C and 7.0, respectively. After a 24-h conversion, the enantiomer excess of (R)-phenylethanediol produced was found to be >99%, with a conversion rate of 56%. In fed-batch fermentations at 30 degrees C for 44 h, glycerol (20 g L(-1)) and corn steep liquor (CSL) (30 g L(-1)) were chosen as the best initial carbon and nitrogen sources, and EH production was markedly improved by pulsed feeding of sucrose (2 g L(-1) h(-1)) and continuous feeding of CSL (1 g L(-1) h(-1)) at a fermentation time of 28 h. After optimization, the maximum dry cell weight achieved was 24.5+/-0.8 g L(-1); maximum EH production was 351.2+/-13.1 U L(-1) with a specific activity of 14.3+/-0.5 U g(-1). Partially purified EH exhibited a temperature optimum at 37 degrees C and pH optimum at 7.5 in 0.1 M phosphate buffer. This study presents the first evidence for the existence of a predicted epoxide racemase, which might be important in the synthesis of epoxide intermediates.
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Affiliation(s)
- Yanbin Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beiyitiao 13, Zhongguancun, Haidian, Beijing, 100080, People's Republic of China
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27
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Zhao L, Schaefer D, Marten MR. Assessment of elasticity and topography of Aspergillus nidulans spores via atomic force microscopy. Appl Environ Microbiol 2005; 71:955-60. [PMID: 15691953 PMCID: PMC546822 DOI: 10.1128/aem.71.2.955-960.2005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies have described both surface morphology and adhesive properties of fungal spores, but little information is currently available on their mechanical properties. In this study, atomic force microscopy (AFM) was used to investigate both surface topography and micromechanical properties of Aspergillus nidulans spores. To assess the influence of proteins covering the spore surface, wild-type spores were compared with spores from isogenic rodA(+) and rodA(-) strains. Tapping-mode AFM images of wild-type and rodA(+) spores in air showed characteristic "rodlet" protein structures covering a granular spore surface. In comparison, rodA(-) spores were rodlet free but showed a granular surface structure similar to that of the wild-type and rodA(+) spores. Rodlets were removed from rodA(+) spores by sonication, uncovering the underlying granular layer. Both rodlet-covered and rodlet-free spores were subjected to nanoindentation measurements, conducted in air, which showed the stiffnesses to be 110 +/- 10, 120 +/- 10, and 300 +/- 20 N/m and the elastic moduli to be 6.6 +/- 0.4, 7.0 +/- 0.7, and 22 +/- 2 GPa for wild-type, rodA(+) and rodA(-) spores, respectively. These results imply the rodlet layer is significantly softer than the underlying portion of the cell wall.
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Affiliation(s)
- Liming Zhao
- Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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28
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Bhargava S, Wenger KS, Rane K, Rising V, Marten MR. Effect of cycle time on fungal morphology, broth rheology, and recombinant enzyme productivity during pulsed addition of limiting carbon source. Biotechnol Bioeng 2005; 89:524-9. [PMID: 15643626 DOI: 10.1002/bit.20355] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
For many years, high broth viscosity has remained a key challenge in large-scale filamentous fungal fermentations. In previous studies, we showed that broth viscosity could be reduced by pulsed addition of limiting carbon during fed-batch fermentation. The objective in this study was to determine how changing the frequency of pulsed substrate addition affects fungal morphology, broth rheology, and recombinant enzyme productivity. To accomplish this, a series of duplicate fed-batch fermentations were performed in 20-L fermentors with a recombinant glucoamylase producing strain of Aspergillus oryzae. The total cycle time for substrate pulsing was varied over a wide range (30-2,700 s), with substrate added only during the first 30% of each cycle. As a control, a fermentation was conducted with continuous substrate feeding, and in all fermentations the same total amount of substrate was added. Results show that the total biomass concentration remained relatively unaltered, while a substantial decrease in the mean projected area of fungal elements (i.e., average size) was observed with increasing cycle time. This led to reduced broth viscosity and increased oxygen uptake rate. However, high values of cycle time (i.e., 900-2,700 s) showed a significant increase in fungal conidia formation and significantly reduced recombinant enzyme productivity, suggesting that the fungi channeled substrate to storage compounds rather than to recombinant protein. In addition to explaining the effect of cycle time on fermentation performance, these results may aid in explaining the discrepancies observed on scale-up to larger fermentors.
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Affiliation(s)
- Swapnil Bhargava
- University of Maryland, Baltimore County, Department of Chemical and Biochemical Engineering, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA
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29
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Wang L, Ridgway D, Gu T, Moo-Young M. Bioprocessing strategies to improve heterologous protein production in filamentous fungal fermentations. Biotechnol Adv 2004; 23:115-29. [PMID: 15694123 DOI: 10.1016/j.biotechadv.2004.11.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2004] [Revised: 11/15/2004] [Accepted: 11/17/2004] [Indexed: 11/24/2022]
Abstract
Filamentous fungi have long been used for the production of metabolites and enzymes. With developments in genetic engineering and molecular biology, filamentous fungi have also achieved increased attention as hosts for recombinant DNA. However, the production levels of non-fungal proteins are usually low. Despite the achievements obtained using molecular tools, the heterologous protein loss caused by extracellular fungal protease degradation persists. This review provides an overview of the potential bioprocessing strategies that can be applied to inhibit protease activity thereby enhancing heterologous protein production.
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Affiliation(s)
- Liping Wang
- Department of Chemical Engineering, Ohio University, Athens, OH 45701, USA
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30
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Impeller types and feeding modes influence the morphology and protein expression in the submerged culture ofAspergillus oryzae. BIOTECHNOL BIOPROC E 2004. [DOI: 10.1007/bf02942290] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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31
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Bhargava S, Wenger KS, Marten MR. Pulsed addition of limiting-carbon during Aspergillus oryzae fermentation leads to improved productivity of a recombinant enzyme. Biotechnol Bioeng 2003; 82:111-7. [PMID: 12569630 DOI: 10.1002/bit.10548] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Fungal morphology in many filamentous fungal fermentations leads to high broth viscosity which limits oxygen mass transfer, and often results in reduced productivity. The objective in this study was to determine if a simple, fed-batch, process strategy-pulsed addition of limiting-carbon source-could be used to reduce fungal broth viscosity, and increase productivity of an industrially relevant recombinant enzyme (glucoamylase). As a control, three Aspergillus oryzae fed-batch fermentations were carried out with continuous addition of limiting-carbon. To determine the effect of pulse-feeding, three additional fermentations were carried out with limiting-carbon added in 90-second pulses, during repeated five-minute cycles. In both cases, overall carbon feed-rate was used to control dissolved oxygen concentration, such that increased oxygen availability led to increased addition of limiting-carbon. Pulse-fed fermentations were found to have smaller fungal mycelia, lower broth viscosity, and improved oxygen mass transfer. As a result, more carbon was added to pulse-fed fermentations that led to increased enzyme productivity by as much as 75%. This finding has significant implications for the bioprocessing industry, as a simple process modification which is likely to cost very little to implement in most production facilities, has the potential to substantially increase productivity.
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Affiliation(s)
- Swapnil Bhargava
- Department of Chemical and Biochemical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA
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