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Saucedo-Gutierrez JJ, Escamilla-García M, Amaro-Reyes A, Carrillo-Garmendia A, Madrigal-Pérez LA, Regalado-González C, Granados-Arvizu JÁ. Differential impacts of furfural and acetic acid on the bioenergetics and fermentation performance of Scheffersomyces stipitis. Fungal Genet Biol 2024; 174:103914. [PMID: 39032808 DOI: 10.1016/j.fgb.2024.103914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 07/10/2024] [Accepted: 07/13/2024] [Indexed: 07/23/2024]
Abstract
Lignocellulosic material is a leading carbon source for economically viable biotechnological processes; however, compounds such furfural and acetic acid exhibit toxicity to yeasts. Nonetheless, research about the molecular mechanism of furfural and acetic acid toxicity is still scarce in yeasts like Scheffersomyces stipitis. Thus, this study aims to elucidate the impact of furfural and acetic acid on S. stipitis regarding bioenergetic and fermentation parameters. Here, we provide evidence that furfural and acetic acid induce a delay in cell growth and extend the lag phase. The mitochondrial membrane potential decreased in all treatments with no significant differences between inhibitors or concentrations. Interestingly, reactive oxygen species increased when the inhibitor concentrations were from 0.1 to 0.3 % (v/v). The glycolytic flux was not significantly (p > 0.05) altered by acetic acid, but furfural caused different effects. Ethanol production decreased significantly (4.32 g·L-1 in furfural and 5.06 g·L-1 in acetic acid) compared to the control (26.3 g·L-1). In contrast, biomass levels were not significantly different in most treatments compared to the control. This study enhances our understanding of the effects of furfural and acetic acid at the mitochondrial level in a pentose-fermenting yeast like S. stipitis.
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Affiliation(s)
- José J Saucedo-Gutierrez
- Facultad de Química, Universidad Autónoma de Querétaro, C.U. Cerro de las Campanas s/n. Col. Las Campanas, C.P. 76010, Querétaro, Qro., México
| | - Monserrat Escamilla-García
- Facultad de Química, Universidad Autónoma de Querétaro, C.U. Cerro de las Campanas s/n. Col. Las Campanas, C.P. 76010, Querétaro, Qro., México
| | - Aldo Amaro-Reyes
- Facultad de Química, Universidad Autónoma de Querétaro, C.U. Cerro de las Campanas s/n. Col. Las Campanas, C.P. 76010, Querétaro, Qro., México
| | - Andrés Carrillo-Garmendia
- Facultad de Química, Universidad Autónoma de Querétaro, C.U. Cerro de las Campanas s/n. Col. Las Campanas, C.P. 76010, Querétaro, Qro., México
| | - Luis A Madrigal-Pérez
- Tecnológico Nacional de México/Instituto Tecnológico Superior de Ciudad Hidalgo, Av. Ing Carlos Rojas Gutiérrez #2120, 61100, Ciudad Hidalgo, Michoacán, México
| | - Carlos Regalado-González
- Facultad de Química, Universidad Autónoma de Querétaro, C.U. Cerro de las Campanas s/n. Col. Las Campanas, C.P. 76010, Querétaro, Qro., México
| | - José Á Granados-Arvizu
- Facultad de Química, Universidad Autónoma de Querétaro, C.U. Cerro de las Campanas s/n. Col. Las Campanas, C.P. 76010, Querétaro, Qro., México.
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Liu C, Choi B, Efimova E, Nygård Y, Santala S. Enhanced upgrading of lignocellulosic substrates by coculture of Saccharomyces cerevisiae and Acinetobacter baylyi ADP1. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:61. [PMID: 38711153 DOI: 10.1186/s13068-024-02510-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 04/23/2024] [Indexed: 05/08/2024]
Abstract
BACKGROUND Lignocellulosic biomass as feedstock has a huge potential for biochemical production. Still, efficient utilization of hydrolysates derived from lignocellulose is challenged by their complex and heterogeneous composition and the presence of inhibitory compounds, such as furan aldehydes. Using microbial consortia where two specialized microbes complement each other could serve as a potential approach to improve the efficiency of lignocellulosic biomass upgrading. RESULTS This study describes the simultaneous inhibitor detoxification and production of lactic acid and wax esters from a synthetic lignocellulosic hydrolysate by a defined coculture of engineered Saccharomyces cerevisiae and Acinetobacter baylyi ADP1. A. baylyi ADP1 showed efficient bioconversion of furan aldehydes present in the hydrolysate, namely furfural and 5-hydroxymethylfurfural, and did not compete for substrates with S. cerevisiae, highlighting its potential as a coculture partner. Furthermore, the remaining carbon sources and byproducts of S. cerevisiae were directed to wax ester production by A. baylyi ADP1. The lactic acid productivity of S. cerevisiae was improved approximately 1.5-fold (to 0.41 ± 0.08 g/L/h) in the coculture with A. baylyi ADP1, compared to a monoculture of S. cerevisiae. CONCLUSION The coculture of yeast and bacterium was shown to improve the consumption of lignocellulosic substrates and the productivity of lactic acid from a synthetic lignocellulosic hydrolysate. The high detoxification capacity and the ability to produce high-value products by A. baylyi ADP1 demonstrates the strain to be a potential candidate for coculture to increase production efficiency and economics of S. cerevisiae fermentations.
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Affiliation(s)
- Changshuo Liu
- Faculty of Engineering and Natural Sciences, Tampere University, Hervanta Campus, Tampere, Finland
| | - Bohyun Choi
- Department of Life Sciences, Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden
| | - Elena Efimova
- Faculty of Engineering and Natural Sciences, Tampere University, Hervanta Campus, Tampere, Finland
| | - Yvonne Nygård
- Department of Life Sciences, Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden
- VTT Technical Research Centre of Finland, Espoo, Finland
| | - Suvi Santala
- Faculty of Engineering and Natural Sciences, Tampere University, Hervanta Campus, Tampere, Finland.
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Gencturk E, Ulgen KO. Understanding HMF inhibition on yeast growth coupled with ethanol production for the improvement of bio-based industrial processes. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Du YH, Wang MY, Yang LH, Tong LL, Guo DS, Ji XJ. Optimization and Scale-Up of Fermentation Processes Driven by Models. Bioengineering (Basel) 2022; 9:bioengineering9090473. [PMID: 36135019 PMCID: PMC9495923 DOI: 10.3390/bioengineering9090473] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/05/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
In the era of sustainable development, the use of cell factories to produce various compounds by fermentation has attracted extensive attention; however, industrial fermentation requires not only efficient production strains, but also suitable extracellular conditions and medium components, as well as scaling-up. In this regard, the use of biological models has received much attention, and this review will provide guidance for the rapid selection of biological models. This paper first introduces two mechanistic modeling methods, kinetic modeling and constraint-based modeling (CBM), and generalizes their applications in practice. Next, we review data-driven modeling based on machine learning (ML), and highlight the application scope of different learning algorithms. The combined use of ML and CBM for constructing hybrid models is further discussed. At the end, we also discuss the recent strategies for predicting bioreactor scale-up and culture behavior through a combination of biological models and computational fluid dynamics (CFD) models.
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Affiliation(s)
- Yuan-Hang Du
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Min-Yu Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Lin-Hui Yang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Ling-Ling Tong
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Dong-Sheng Guo
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
- Correspondence: (D.-S.G.); (X.-J.J.)
| | - Xiao-Jun Ji
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
- Correspondence: (D.-S.G.); (X.-J.J.)
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Patra P, Das M, Kundu P, Ghosh A. Recent advances in systems and synthetic biology approaches for developing novel cell-factories in non-conventional yeasts. Biotechnol Adv 2021; 47:107695. [PMID: 33465474 DOI: 10.1016/j.biotechadv.2021.107695] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 12/14/2020] [Accepted: 01/09/2021] [Indexed: 12/14/2022]
Abstract
Microbial bioproduction of chemicals, proteins, and primary metabolites from cheap carbon sources is currently an advancing area in industrial research. The model yeast, Saccharomyces cerevisiae, is a well-established biorefinery host that has been used extensively for commercial manufacturing of bioethanol from myriad carbon sources. However, its Crabtree-positive nature often limits the use of this organism for the biosynthesis of commercial molecules that do not belong in the fermentative pathway. To avoid extensive strain engineering of S. cerevisiae for the production of metabolites other than ethanol, non-conventional yeasts can be selected as hosts based on their natural capacity to produce desired commodity chemicals. Non-conventional yeasts like Kluyveromyces marxianus, K. lactis, Yarrowia lipolytica, Pichia pastoris, Scheffersomyces stipitis, Hansenula polymorpha, and Rhodotorula toruloides have been considered as potential industrial eukaryotic hosts owing to their desirable phenotypes such as thermotolerance, assimilation of a wide range of carbon sources, as well as ability to secrete high titers of protein and lipid. However, the advanced metabolic engineering efforts in these organisms are still lacking due to the limited availability of systems and synthetic biology methods like in silico models, well-characterised genetic parts, and optimized genome engineering tools. This review provides an insight into the recent advances and challenges of systems and synthetic biology as well as metabolic engineering endeavours towards the commercial usage of non-conventional yeasts. Particularly, the approaches in emerging non-conventional yeasts for the production of enzymes, therapeutic proteins, lipids, and metabolites for commercial applications are extensively discussed here. Various attempts to address current limitations in designing novel cell factories have been highlighted that include the advances in the fields of genome-scale metabolic model reconstruction, flux balance analysis, 'omics'-data integration into models, genome-editing toolkit development, and rewiring of cellular metabolisms for desired chemical production. Additionally, the understanding of metabolic networks using 13C-labelling experiments as well as the utilization of metabolomics in deciphering intracellular fluxes and reactions have also been discussed here. Application of cutting-edge nuclease-based genome editing platforms like CRISPR/Cas9, and its optimization towards efficient strain engineering in non-conventional yeasts have also been described. Additionally, the impact of the advances in promising non-conventional yeasts for efficient commercial molecule synthesis has been meticulously reviewed. In the future, a cohesive approach involving systems and synthetic biology will help in widening the horizon of the use of unexplored non-conventional yeast species towards industrial biotechnology.
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Affiliation(s)
- Pradipta Patra
- School of Energy Science and Engineering, Indian Institute of Technology Kharagpur, West Bengal 721302, India
| | - Manali Das
- School of Bioscience, Indian Institute of Technology Kharagpur, West Bengal 721302, India
| | - Pritam Kundu
- School of Energy Science and Engineering, Indian Institute of Technology Kharagpur, West Bengal 721302, India
| | - Amit Ghosh
- School of Energy Science and Engineering, Indian Institute of Technology Kharagpur, West Bengal 721302, India; P.K. Sinha Centre for Bioenergy and Renewables, Indian Institute of Technology Kharagpur, West Bengal 721302, India.
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Cabaneros Lopez P, Udugama IA, Thomsen ST, Roslander C, Junicke H, Iglesias MM, Gernaey KV. Transforming data to information: A parallel hybrid model for real-time state estimation in lignocellulosic ethanol fermentation. Biotechnol Bioeng 2020; 118:579-591. [PMID: 33002188 PMCID: PMC7894558 DOI: 10.1002/bit.27586] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/17/2020] [Accepted: 09/26/2020] [Indexed: 11/21/2022]
Abstract
Operating lignocellulosic fermentation processes to produce fuels and chemicals is challenging due to the inherent complexity and variability of the fermentation media. Real‐time monitoring is necessary to compensate for these challenges, but the traditional process monitoring methods fail to deliver actionable information that can be used to implement advanced control strategies. In this study, a hybrid‐modeling approach is presented to monitor cellulose‐to‐ethanol (EtOH) fermentations in real‐time. The hybrid approach uses a continuous‐discrete extended Kalman filter to reconciliate the predictions of a data‐driven model and a kinetic model and to estimate the concentration of glucose (Glu), xylose (Xyl), and EtOH. The data‐driven model is based on partial least squares (PLS) regression and predicts in real‐time the concentration of Glu, Xyl, and EtOH from spectra collected with attenuated total reflectance mid‐infrared spectroscopy. The estimations made by the hybrid approach, the data‐driven models and the internal model were compared in two validation experiments showing that the hybrid model significantly outperformed the PLS and improved the predictions of the internal model. Furthermore, the hybrid model delivered consistent estimates even when disturbances in the measurements occurred, demonstrating the robustness of the method. The consistency of the proposed hybrid model opens the doors towards the implementation of advanced feedback control schemes.
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Affiliation(s)
- Pau Cabaneros Lopez
- Department of Chemical and Biochemical Engineering, Process and Systems Engineering Center (PROSYS), Technical University of Denmark (DTU), Lyngby, Denmark
| | - Isuru A Udugama
- Department of Chemical and Biochemical Engineering, Process and Systems Engineering Center (PROSYS), Technical University of Denmark (DTU), Lyngby, Denmark
| | - Sune T Thomsen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark
| | | | - Helena Junicke
- Department of Chemical and Biochemical Engineering, Process and Systems Engineering Center (PROSYS), Technical University of Denmark (DTU), Lyngby, Denmark
| | - Miguel M Iglesias
- Department of Chemical Engineering, CRETUS Institute, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Krist V Gernaey
- Department of Chemical and Biochemical Engineering, Process and Systems Engineering Center (PROSYS), Technical University of Denmark (DTU), Lyngby, Denmark
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Terán Hilares R, Dionízio RM, Sánchez Muñoz S, Prado CA, de Sousa Júnior R, da Silva SS, Santos JC. Hydrodynamic cavitation-assisted continuous pre-treatment of sugarcane bagasse for ethanol production: Effects of geometric parameters of the cavitation device. ULTRASONICS SONOCHEMISTRY 2020; 63:104931. [PMID: 31945566 DOI: 10.1016/j.ultsonch.2019.104931] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 06/10/2023]
Abstract
For biotechnological conversion of lignocellulosic biomass, a pre-treatment step is required before enzymatic hydrolysis of carbohydrate fractions of the material, which is required to produce fermentable sugars for generation of ethanol or other products in a biorefinery. The most of the reported pre-treatment technologies are in batch operation mode, presenting some disadvantages as dead times in the process. In this context, hydrodynamic cavitation (HC)-assisted alkaline hydrogen peroxide (AHP) pre-treatment in continuous process was proposed for pre-treatment of sugarcane bagasse (SCB). The system was designed with a main reactor containing two devices to generate cavitation by passing liquid medium through orifice plates. For SCB pretreated in continuous process, 52.79, 34.31, 22.13 and 15.81 g of total reducing sugars (TRS) per 100 g of SCB were released in samples pretreated using orifice plates with a number of holes of 24 (d = 0.45 mm), 16 (d = 0.65 mm), 12 (d = 0.8 mm) and 8 (d = 1 mm), respectively. Computational Fluid Dynamics (CFD) tools showed that 0.94 of vapor phase volume fraction and 0.19 of cavitation number were achieved at 31 m/s of throat velocity and upstream pressure of 350,000 Pa. By using pretreated SCB, 28.44 g of ethanol/L (84.31% of yield respect to theoretical value) was produced by immobilized Scheffersomyces stipitis NRRL-Y7124 in a simultaneous hydrolysis and fermentation process at high solid loading (16% S/L). Thus, HC-assisted process was proved as a promising technology for valorization of lignocellulosic biomass.
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Affiliation(s)
- Ruly Terán Hilares
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CEP: 12602-810 Lorena, SP, Brazil; Laboratório de Materiales, Universidad Católica de Santa Maria - UCSM, Urb. San José, San Jose s/n, Yanahuara, Arequipa, Perú.
| | - Rafaela Medeiros Dionízio
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CEP: 12602-810 Lorena, SP, Brazil
| | - Salvador Sánchez Muñoz
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CEP: 12602-810 Lorena, SP, Brazil
| | - Carina Aline Prado
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CEP: 12602-810 Lorena, SP, Brazil
| | - Ruy de Sousa Júnior
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rod. Washington Luís-km 235, CEP: 13565-905 São Carlos, SP, Brazil
| | - Silvio Silvério da Silva
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CEP: 12602-810 Lorena, SP, Brazil
| | - Júlio César Santos
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CEP: 12602-810 Lorena, SP, Brazil.
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Ravikrishnan A, Blank LM, Srivastava S, Raman K. Investigating metabolic interactions in a microbial co-culture through integrated modelling and experiments. Comput Struct Biotechnol J 2020; 18:1249-1258. [PMID: 32551031 PMCID: PMC7286961 DOI: 10.1016/j.csbj.2020.03.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 02/10/2020] [Accepted: 03/20/2020] [Indexed: 01/13/2023] Open
Abstract
Microbial co-cultures have been used in several biotechnological applications. Within these co-cultures, the microorganisms tend to interact with each other and perform complex actions. Investigating metabolic interactions in microbial co-cultures is crucial in designing microbial consortia. Here, we present a pipeline integrating modelling and experimental approaches to understand metabolic interactions between organisms in a community. We define a new index named "Metabolic Support Index (MSI)", which quantifies the benefits derived by each organism in the presence of the other when grown as a co-culture. We computed MSI for several experimentally demonstrated co-cultures and showed that MSI, as a metric, accurately identifies the organism that derives the maximum benefit. We also computed MSI for a commonly used yeast co-culture consisting of Saccharomyces cerevisiae and Pichia stipitis and observed that the latter derives higher benefit from the interaction. Further, we designed two-stage experiments to study mutual interactions and showed that P. stipitis indeed derives the maximum benefit from the interaction, as shown from our computational predictions. Also, using our previously developed computational tool MetQuest, we identified all the metabolic exchanges happening between these organisms by analysing the pathways spanning the two organisms. By analysing the HPLC profiles and studying the isotope labelling, we show that P. stipitis consumes the ethanol produced by S. cerevisiae when grown on glucose-rich medium under aerobic conditions, as also indicated by our in silico pathway analyses. Our approach represents an important step in understanding metabolic interactions in microbial communities through an integrated computational and experimental workflow.
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Affiliation(s)
- Aarthi Ravikrishnan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology (IIT) Madras, Chennai 600 036, India
- Initiative for Biological Systems Engineering, IIT Madras, India
- Robert Bosch Centre for Data Science and Artificial Intelligence, IIT Madras, India
- Institute of Applied Microbiology - iAMB, Aachen Biology and Biotechnology – ABBt, Worringer Weg 1, RWTH Aachen University, D-52074 Aachen, Germany
| | - Lars M. Blank
- Institute of Applied Microbiology - iAMB, Aachen Biology and Biotechnology – ABBt, Worringer Weg 1, RWTH Aachen University, D-52074 Aachen, Germany
| | - Smita Srivastava
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology (IIT) Madras, Chennai 600 036, India
| | - Karthik Raman
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology (IIT) Madras, Chennai 600 036, India
- Initiative for Biological Systems Engineering, IIT Madras, India
- Robert Bosch Centre for Data Science and Artificial Intelligence, IIT Madras, India
- Corresponding author.
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Bridging substrate intake kinetics and bacterial growth phenotypes with flux balance analysis incorporating proteome allocation. Sci Rep 2020; 10:4283. [PMID: 32152336 PMCID: PMC7062752 DOI: 10.1038/s41598-020-61174-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 02/24/2020] [Indexed: 11/08/2022] Open
Abstract
Empirical kinetic models such as the Monod equation have been widely applied to relate the cell growth with substrate availability. The Monod equation shares a similar form with the mechanistically-based Michaelis-Menten kinetics for enzymatic processes, which has provoked long-standing and un-concluded conjectures on their relationship. In this work, we integrated proteome allocation principles into a Flux Balance Analysis (FBA) model of Escherichia coli, which quantitatively revealed potential mechanisms that underpin the phenomenological Monod parameters: the maximum specific growth rate could be dictated by the abundance of growth-controlling proteome and growth-pertinent proteome cost; more importantly, the Monod constant (Ks) was shown to relate to the Michaelis constant for substrate transport (Km,g), with the link being dependent on the cell's metabolic strategy. Besides, the proposed model was able to predict glucose uptake rate at given external glucose concentration through the size of available proteome resource for substrate transport and its enzymatic cost, while growth rate and acetate overflow were accurately simulated for two E. coli strains. Bridging the enzymatic kinetics of substrate intake and overall growth phenotypes, this work offers a mechanistic interpretation to the empirical Monod law, and demonstrates the potential of coupling local and global cellular constrains in predictive modelling.
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Yan Y, Bu C, He Q, Zheng Z, Ouyang J. Efficient bioconversion of furfural to furfuryl alcohol by Bacillus coagulans NL01. RSC Adv 2018; 8:26720-26727. [PMID: 35541055 PMCID: PMC9083097 DOI: 10.1039/c8ra05098h] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 07/06/2018] [Indexed: 11/21/2022] Open
Abstract
Bio-catalysis is an attractive alternative to replace chemical methods due to its high selectivity and mild reaction conditions. Furfural is an important bio-based platform compound generated from biomass. Herein, the bio-catalytic reduction of furfural (FAL) to furfuryl alcohol (FOL) was performed by using a furfural tolerant strain, Bacillus coagulans NL01. An efficient co-substrate was explored and a high conversion and selectivity of FAL to FOL was reported over this bio-catalytic system using glucose as co-substrate. As the bioconversion occurred over 42 mM FAL, 20 g L-1 glucose and 9 mg mL-1 at 50 °C, a high conversion and selectivity was obtained by 3 h reaction. This transformation rate of FAL was the highest compared with other reactions. Furthermore, about 98 mM FOL was produced from FAL within 24 h by a fed-batch strategy with a conversion of 92% and selectivity of 96%. These results indicate that this bio-catalytic reduction of FAL has high potential for application to upgrading of FAL and B. coagulans NL01 is a promising biocatalyst for the synthesis of FOL. In addition, this bio-catalytic reduction shows a high potential application for catalytic upgrading of FAL from biomass.
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Affiliation(s)
- Yuxiu Yan
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University 159 Longpan Road Nanjing 210037 China
- College of Forestry, Nanjing Forestry University Nanjing 210037 China
| | - Chongyang Bu
- College of Chemical Engineering, Nanjing Forestry University Nanjing 210037 China
| | - Qin He
- College of Chemical Engineering, Nanjing Forestry University Nanjing 210037 China
| | - Zhaojuan Zheng
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University 159 Longpan Road Nanjing 210037 China
| | - Jia Ouyang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University 159 Longpan Road Nanjing 210037 China
- College of Chemical Engineering, Nanjing Forestry University Nanjing 210037 China
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Perna MDSC, Bastos RG, Ceccato-Antonini SR. Single and combined effects of acetic acid, furfural, and sugars on the growth of the pentose-fermenting yeast Meyerozyma guilliermondii. 3 Biotech 2018; 8:119. [PMID: 29430380 PMCID: PMC5803134 DOI: 10.1007/s13205-018-1143-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/30/2018] [Indexed: 01/25/2023] Open
Abstract
The tolerance of the pentose-fermenting yeast Meyerozyma guilliermondii to the inhibitors released after the biomass hydrolysis, such as acetic acid and furfural, was surveyed. We first verified the effects of acetic acid and cell concentrations and initial pH on the growth of a M. guilliermondii strain in a semi-synthetic medium containing acetic acid as the sole carbon source. Second, the single and combined effects of furfural, acetic acid, and sugars (xylose, arabinose, and glucose) on the sugar uptake, cell growth, and ethanol production were also analysed. Growth inhibition occurred in concentrations higher than 10.5 g l-1 acetic acid and initial pH 3.5. The maximum specific growth rate (µ) was 0.023 h-1 and the saturation constant (ks) was 0.75 g l-1 acetic acid. Initial cell concentration also influenced µ. Acetic acid (initial concentration 5 g l-1) was co-consumed with sugars even in the presence of 20 mg l-1 furfural without inhibition to the yeast growth. The yeast grew and fermented sugars in a sugar-based medium with acetic acid and furfural in concentrations much higher than those usually found in hemicellulosic hydrolysates.
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Affiliation(s)
- Michelle dos Santos Cordeiro Perna
- Laboratory of Molecular and Agricultural Microbiology, Dept Tecnologia Agroindustrial e Sócio-Economia Rural, Centro de Ciências Agrárias, Universidade Federal de São Carlos, P.O. Box 153, Araras, São Paulo State 13600-970 Brazil
| | - Reinaldo Gaspar Bastos
- Laboratory of Molecular and Agricultural Microbiology, Dept Tecnologia Agroindustrial e Sócio-Economia Rural, Centro de Ciências Agrárias, Universidade Federal de São Carlos, P.O. Box 153, Araras, São Paulo State 13600-970 Brazil
| | - Sandra Regina Ceccato-Antonini
- Laboratory of Molecular and Agricultural Microbiology, Dept Tecnologia Agroindustrial e Sócio-Economia Rural, Centro de Ciências Agrárias, Universidade Federal de São Carlos, P.O. Box 153, Araras, São Paulo State 13600-970 Brazil
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Acevedo A, Conejeros R, Aroca G. Ethanol production improvement driven by genome-scale metabolic modeling and sensitivity analysis in Scheffersomyces stipitis. PLoS One 2017; 12:e0180074. [PMID: 28658270 PMCID: PMC5489217 DOI: 10.1371/journal.pone.0180074] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 06/11/2017] [Indexed: 11/18/2022] Open
Abstract
The yeast Scheffersomyces stipitis naturally produces ethanol from xylose, however reaching high ethanol yields is strongly dependent on aeration conditions. It has been reported that changes in the availability of NAD(H/+) cofactors can improve fermentation in some microorganisms. In this work genome-scale metabolic modeling and phenotypic phase plane analysis were used to characterize metabolic response on a range of uptake rates. Sensitivity analysis was used to assess the effect of ARC on ethanol production indicating that modifying ARC by inhibiting the respiratory chain ethanol production can be improved. It was shown experimentally in batch culture using Rotenone as an inhibitor of the mitochondrial NADH dehydrogenase complex I (CINADH), increasing ethanol yield by 18%. Furthermore, trajectories for uptakes rates, specific productivity and specific growth rate were determined by modeling the batch culture, to calculate ARC associated to the addition of CINADH inhibitor. Results showed that the increment in ethanol production via respiratory inhibition is due to excess in ARC, which generates an increase in ethanol production. Thus ethanol production improvement could be predicted by a change in ARC.
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Affiliation(s)
- Alejandro Acevedo
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2085, Valparaíso, Chile
| | - Raúl Conejeros
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2085, Valparaíso, Chile
- * E-mail:
| | - Germán Aroca
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2085, Valparaíso, Chile
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14
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Bosi E, Bacci G, Mengoni A, Fondi M. Perspectives and Challenges in Microbial Communities Metabolic Modeling. Front Genet 2017; 8:88. [PMID: 28680442 PMCID: PMC5478693 DOI: 10.3389/fgene.2017.00088] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/09/2017] [Indexed: 01/31/2023] Open
Abstract
Bacteria have evolved to efficiently interact each other, forming complex entities known as microbial communities. These "super-organisms" play a central role in maintaining the health of their eukaryotic hosts and in the cycling of elements like carbon and nitrogen. However, despite their crucial importance, the mechanisms that influence the functioning of microbial communities and their relationship with environmental perturbations are obscure. The study of microbial communities was boosted by tremendous advances in sequencing technologies, and in particular by the possibility to determine genomic sequences of bacteria directly from environmental samples. Indeed, with the advent of metagenomics, it has become possible to investigate, on a previously unparalleled scale, the taxonomical composition and the functional genetic elements present in a specific community. Notwithstanding, the metagenomic approach per se suffers some limitations, among which the impossibility of modeling molecular-level (e.g., metabolic) interactions occurring between community members, as well as their effects on the overall stability of the entire system. The family of constraint-based methods, such as flux balance analysis, has been fruitfully used to translate genome sequences in predictive, genome-scale modeling platforms. Although these techniques have been initially developed for analyzing single, well-known model organisms, their recent improvements allowed engaging in multi-organism in silico analyses characterized by a considerable predictive capability. In the face of these advances, here we focus on providing an overview of the possibilities and challenges related to the modeling of metabolic interactions within a bacterial community, discussing the feasibility and the perspectives of this kind of analysis in the (near) future.
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Affiliation(s)
| | | | - Alessio Mengoni
- Department of Biology, University of FlorenceFlorence, Italy
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15
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Peng X“N, Gilmore SP, O’Malley MA. Microbial communities for bioprocessing: lessons learned from nature. Curr Opin Chem Eng 2016. [DOI: 10.1016/j.coche.2016.09.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Sánchez BJ, Nielsen J. Genome scale models of yeast: towards standardized evaluation and consistent omic integration. Integr Biol (Camb) 2016; 7:846-58. [PMID: 26079294 DOI: 10.1039/c5ib00083a] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Genome scale models (GEMs) have enabled remarkable advances in systems biology, acting as functional databases of metabolism, and as scaffolds for the contextualization of high-throughput data. In the case of Saccharomyces cerevisiae (budding yeast), several GEMs have been published and are currently used for metabolic engineering and elucidating biological interactions. Here we review the history of yeast's GEMs, focusing on recent developments. We study how these models are typically evaluated, using both descriptive and predictive metrics. Additionally, we analyze the different ways in which all levels of omics data (from gene expression to flux) have been integrated in yeast GEMs. Relevant conclusions and current challenges for both GEM evaluation and omic integration are highlighted.
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Affiliation(s)
- Benjamín J Sánchez
- Department of Biology and Biological Engineering, Chalmers University of Technology, SE41296 Gothenburg, Sweden.
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17
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Unrean P. Bioprocess modelling for the design and optimization of lignocellulosic biomass fermentation. BIORESOUR BIOPROCESS 2016. [DOI: 10.1186/s40643-015-0079-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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18
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Abstract
Most natural microbial systems have evolved to function in environments with temporal and spatial variations. A major limitation to understanding such complex systems is the lack of mathematical modelling frameworks that connect the genomes of individual species and temporal and spatial variations in the environment to system behaviour. The goal of this review is to introduce the emerging field of spatiotemporal metabolic modelling based on genome-scale reconstructions of microbial metabolism. The extension of flux balance analysis (FBA) to account for both temporal and spatial variations in the environment is termed spatiotemporal FBA (SFBA). Following a brief overview of FBA and its established dynamic extension, the SFBA problem is introduced and recent progress is described. Three case studies are reviewed to illustrate the current state-of-the-art and possible future research directions are outlined. The author posits that SFBA is the next frontier for microbial metabolic modelling and a rapid increase in methods development and system applications is anticipated.
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Affiliation(s)
- Michael A Henson
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, U.S.A.
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19
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Zomorrodi AR, Segrè D. Synthetic Ecology of Microbes: Mathematical Models and Applications. J Mol Biol 2015; 428:837-61. [PMID: 26522937 DOI: 10.1016/j.jmb.2015.10.019] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 10/17/2015] [Accepted: 10/21/2015] [Indexed: 12/29/2022]
Abstract
As the indispensable role of natural microbial communities in many aspects of life on Earth is uncovered, the bottom-up engineering of synthetic microbial consortia with novel functions is becoming an attractive alternative to engineering single-species systems. Here, we summarize recent work on synthetic microbial communities with a particular emphasis on open challenges and opportunities in environmental sustainability and human health. We next provide a critical overview of mathematical approaches, ranging from phenomenological to mechanistic, to decipher the principles that govern the function, dynamics and evolution of microbial ecosystems. Finally, we present our outlook on key aspects of microbial ecosystems and synthetic ecology that require further developments, including the need for more efficient computational algorithms, a better integration of empirical methods and model-driven analysis, the importance of improving gene function annotation, and the value of a standardized library of well-characterized organisms to be used as building blocks of synthetic communities.
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Affiliation(s)
| | - Daniel Segrè
- Bioinformatics Program, Boston University, Boston, MA; Department of Biology, Boston University, Boston, MA; Department of Biomedical Engineering, Boston University, Boston, MA.
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20
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Unrean P, Khajeeram S. Model-based optimization of Scheffersomyces stipitis and Saccharomyces cerevisiae co-culture for efficient lignocellulosic ethanol production. BIORESOUR BIOPROCESS 2015. [DOI: 10.1186/s40643-015-0069-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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21
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Biggs MB, Medlock GL, Kolling GL, Papin JA. Metabolic network modeling of microbial communities. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2015; 7:317-34. [PMID: 26109480 DOI: 10.1002/wsbm.1308] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/07/2015] [Accepted: 05/13/2015] [Indexed: 12/15/2022]
Abstract
Genome-scale metabolic network reconstructions and constraint-based analyses are powerful methods that have the potential to make functional predictions about microbial communities. Genome-scale metabolic networks are used to characterize the metabolic functions of microbial communities via several techniques including species compartmentalization, separating species-level and community-level objectives, dynamic analysis, the 'enzyme-soup' approach, multiscale modeling, and others. There are many challenges in the field, including a need for tools that accurately assign high-level omics signals to individual community members, the need for improved automated network reconstruction methods, and novel algorithms for integrating omics data and engineering communities. As technologies and modeling frameworks improve, we expect that there will be corresponding advances in the fields of ecology, health science, and microbial community engineering.
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Affiliation(s)
- Matthew B Biggs
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Gregory L Medlock
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Glynis L Kolling
- Department of Medicine, Infectious Diseases, University of Virginia, Charlottesville, VA, USA
| | - Jason A Papin
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
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22
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Pornkamol U, Franzen CJ. Dynamic flux balancing elucidates NAD(P)H production as limiting response to furfural inhibition in Saccharomyces cerevisiae. Biotechnol J 2015; 10:1248-58. [PMID: 25880365 DOI: 10.1002/biot.201400833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 02/13/2015] [Accepted: 04/13/2015] [Indexed: 12/20/2022]
Abstract
Achieving efficient and economical lignocellulose-based bioprocess requires a robust organism tolerant to furfural, a major inhibitory compound present in lignocellulosic hydrolysate. The aim of this study was to develop a model that could generate quantitative descriptions of cell metabolism for elucidating the cell's adaptive response to furfural. Such a modelling tool could provide strategies for the design of more robust cells. A dynamic flux balance (dFBA) model of Saccharomyces cerevisiae was created by coupling a kinetic fermentation model with a previously published genome-scale stoichiometric model. The dFBA model was used for studying intracellular and extracellular flux responses to furfural perturbations under steady state and dynamic conditions. The predicted effects of furfural on dynamic flux profiles agreed well with previously published experimental results. The model showed that the yeast cell adjusts its metabolism in response to furfural challenge by increasing fluxes through the pentose phosphate pathway, TCA cycle, and proline and serine biosynthesis in order to meet the high demand of NAD(P)H cofactors. The model described here can be used to aid in systematic optimization of the yeast, as well as of the fermentation process, for efficient lignocellulosic ethanol production.
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Affiliation(s)
- Unrean Pornkamol
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand.
| | - Carl J Franzen
- Chalmers University of Technology, Department of Chemical and Biological Engineering, Division of Life Science - Industrial Biotechnology, Gothenburg, Sweden
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23
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Kerkhoven EJ, Lahtvee PJ, Nielsen J. Applications of computational modeling in metabolic engineering of yeast. FEMS Yeast Res 2015; 15:1-13. [PMID: 25156867 DOI: 10.1111/1567-1364.12199] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 05/28/2014] [Accepted: 08/19/2014] [Indexed: 12/13/2022] Open
Abstract
Generally, a microorganism's phenotype can be described by its pattern of metabolic fluxes. Although fluxes cannot be measured directly, inference of fluxes is well established. In biotechnology the aim is often to increase the capacity of specific fluxes. For this, metabolic engineering methods have been developed and applied extensively. Many of these rely on balancing of intracellular metabolites, redox, and energy fluxes, using genome-scale models (GEMs) that in combination with appropriate objective functions and constraints can be used to predict potential gene targets for obtaining a preferred flux distribution. These methods point to strategies for altering gene expression; however, fluxes are often controlled by post-transcriptional events. Moreover, GEMs are usually not taking into account metabolic regulation, thermodynamics and enzyme kinetics. To facilitate metabolic engineering, tools from synthetic biology have emerged, enabling integration and assembly of naturally nonexistent, but well-characterized components into a living organism. To describe these systems kinetic models are often used and to integrate these systems with the standard metabolic engineering approach, it is necessary to expand the modeling of metabolism to consider kinetics of individual processes. This review will give an overview about models available for metabolic engineering of yeast and discusses their applications.
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Affiliation(s)
- Eduard J Kerkhoven
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Petri-Jaan Lahtvee
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Gothenburg, Sweden
| | - Jens Nielsen
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden .,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Gothenburg, Sweden.,Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Gothenburg, Sweden
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24
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Senger RS, Yen JY, Fong SS. A review of genome-scale metabolic flux modeling of anaerobiosis in biotechnology. Curr Opin Chem Eng 2014. [DOI: 10.1016/j.coche.2014.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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25
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Henson MA, Hanly TJ. Dynamic flux balance analysis for synthetic microbial communities. IET Syst Biol 2014; 8:214-29. [PMID: 25257022 PMCID: PMC8687154 DOI: 10.1049/iet-syb.2013.0021] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 01/14/2023] Open
Abstract
Dynamic flux balance analysis (DFBA) is an extension of classical flux balance analysis that allows the dynamic effects of the extracellular environment on microbial metabolism to be predicted and optimised. Recently this computational framework has been extended to microbial communities for which the individual species are known and genome-scale metabolic reconstructions are available. In this review, the authors provide an overview of the emerging DFBA approach with a focus on two case studies involving the conversion of mixed hexose/pentose sugar mixtures by synthetic microbial co-culture systems. These case studies illustrate the key requirements of the DFBA approach, including the incorporation of individual species metabolic reconstructions, formulation of extracellular mass balances, identification of substrate uptake kinetics, numerical solution of the coupled linear program/differential equations and model adaptation for common, suboptimal growth conditions and identified species interactions. The review concludes with a summary of progress to date and possible directions for future research.
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Affiliation(s)
- Michael A Henson
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01007, USA.
| | - Timothy J Hanly
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01007, USA
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26
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Acevedo A, Aroca G, Conejeros R. Genome-scale NAD(H/(+)) availability patterns as a differentiating feature between Saccharomyces cerevisiae and Scheffersomyces stipitis in relation to fermentative metabolism. PLoS One 2014; 9:e87494. [PMID: 24489927 PMCID: PMC3906188 DOI: 10.1371/journal.pone.0087494] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/26/2013] [Indexed: 11/18/2022] Open
Abstract
Scheffersomyces stipitis is a yeast able to ferment pentoses to ethanol, unlike Saccharomyces cerevisiae, it does not present the so-called overflow phenomenon. Metabolic features characterizing the presence or not of this phenomenon have not been fully elucidated. This work proposes that genome-scale metabolic response to variations in NAD(H/+) availability characterizes fermentative behavior in both yeasts. Thus, differentiating features in S. stipitis and S. cerevisiae were determined analyzing growth sensitivity response to changes in available reducing capacity in relation to ethanol production capacity and overall metabolic flux span. Using genome-scale constraint-based metabolic models, phenotypic phase planes and shadow price analyses, an excess of available reducing capacity for growth was found in S. cerevisiae at every metabolic phenotype where growth is limited by oxygen uptake, while in S. stipitis this was observed only for a subset of those phenotypes. Moreover, by using flux variability analysis, an increased metabolic flux span was found in S. cerevisiae at growth limited by oxygen uptake, while in S. stipitis flux span was invariant. Therefore, each yeast can be characterized by a significantly different metabolic response and flux span when growth is limited by oxygen uptake, both features suggesting a higher metabolic flexibility in S. cerevisiae. By applying an optimization-based approach on the genome-scale models, three single reaction deletions were found to generate in S. stipitis the reducing capacity availability pattern found in S. cerevisiae, two of them correspond to reactions involved in the overflow phenomenon. These results show a close relationship between the growth sensitivity response given by the metabolic network and fermentative behavior.
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Affiliation(s)
- Alejandro Acevedo
- Escuela de Ingeniería Bioquímica/Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Bioenercel S.A., Barrio Universitario, Concepción, Chile
| | - German Aroca
- Escuela de Ingeniería Bioquímica/Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Bioenercel S.A., Barrio Universitario, Concepción, Chile
| | - Raul Conejeros
- Escuela de Ingeniería Bioquímica/Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Bioenercel S.A., Barrio Universitario, Concepción, Chile
- * E-mail:
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