1
|
Tiang MF, Hanipa MAF, Mahmod SS, Zainuddin MT, Lutfi AAI, Jahim JM, Takriff MS, Reungsang A, Wu SY, Abdul PM. Impact of light spectra on photo-fermentative biohydrogen production by Rhodobacter sphaeroides KKU-PS1. BIORESOURCE TECHNOLOGY 2024; 394:130222. [PMID: 38109981 DOI: 10.1016/j.biortech.2023.130222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 12/15/2023] [Accepted: 12/15/2023] [Indexed: 12/20/2023]
Abstract
Purple non-sulphur bacteria can only capture up to 10 % light spectra and only 1-5 % of light is converted efficiently for biohydrogen production. To enhance light capture and conversion efficiencies, it is necessary to understand the impact of various light spectra on light harvesting pigments. During photo-fermentation, Rhodobacter sphaeroides KKU-PS1 cultivated at 30 °C and 150 rpm under different light spectra has been investigated. Results revealed that red light is more beneficial for biomass accumulation, whereas green light showed the greatest impact on photo-fermentative biohydrogen production. Light conversion efficiency by green light is 2-folds of that under control white light, hence photo-hydrogen productivity is ranked as green > red > orange > violet > blue > yellow. These experimental data demonstrated that green and red lights are essential for photo-hydrogen and biomass productions of R. sphaeroides and a clearer understanding that possibly pave the way for further photosynthetic enhancement research.
Collapse
Affiliation(s)
- Ming Foong Tiang
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia
| | - Muhammad Alif Fitri Hanipa
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia
| | - Safa Senan Mahmod
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia; Faculty of Chemical Engineering & Technology, Universiti Malaysia Perlis, UniMAP, 02600 Arau, Perlis, Malaysia; Centre of Excellence for Biomass Utilization, Universiti Malaysia Perlis, UniMAP, 02600 Arau, Perlis, Malaysia
| | - Muhammad Tarmidzi Zainuddin
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia
| | - Abdullah Amru Indera Lutfi
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia; Research Centre for Sustainable Process Technology (CESPRO), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bandar Baru Bangi, Selangor Darul Ehsan, Malaysia
| | - Jamaliah Md Jahim
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia; Research Centre for Sustainable Process Technology (CESPRO), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bandar Baru Bangi, Selangor Darul Ehsan, Malaysia
| | - Mohd Sobri Takriff
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia; Research Centre for Sustainable Process Technology (CESPRO), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bandar Baru Bangi, Selangor Darul Ehsan, Malaysia; Department of Mechanical and Nuclear Engineering, College of Engineering, University of Sharjah, United Arab Emirates
| | - Alissara Reungsang
- Department of Biotechnology, Faculty of Technology, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Shu-Yii Wu
- Department of Chemical Engineering, Feng Chia University, Taichung 40724, Taiwan; Green Energy Development Center, Feng Chia University, Taichung 40724, Taiwan
| | - Peer Mohamed Abdul
- Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia; Centre of Excellence for Biomass Utilization, Universiti Malaysia Perlis, UniMAP, 02600 Arau, Perlis, Malaysia; Research Centre for Sustainable Process Technology (CESPRO), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bandar Baru Bangi, Selangor Darul Ehsan, Malaysia.
| |
Collapse
|
2
|
Helmy M, Elhalis H, Liu Y, Chow Y, Selvarajoo K. Perspective: Multiomics and Machine Learning Help Unleash the Alternative Food Potential of Microalgae. Adv Nutr 2023; 14:1-11. [PMID: 36811582 PMCID: PMC9780023 DOI: 10.1016/j.advnut.2022.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 10/31/2022] [Accepted: 11/09/2022] [Indexed: 12/24/2022] Open
Abstract
Food security has become a pressing issue in the modern world. The ever-increasing world population, ongoing COVID-19 pandemic, and political conflicts together with climate change issues make the problem very challenging. Therefore, fundamental changes to the current food system and new sources of alternative food are required. Recently, the exploration of alternative food sources has been supported by numerous governmental and research organizations, as well as by small and large commercial ventures. Microalgae are gaining momentum as an effective source of alternative laboratory-based nutritional proteins as they are easy to grow under variable environmental conditions, with the added advantage of absorbing carbon dioxide. Despite their attractiveness, the utilization of microalgae faces several practical limitations. Here, we discuss both the potential and challenges of microalgae in food sustainability and their possible long-term contribution to the circular economy of converting food waste into feed via modern methods. We also argue that systems biology and artificial intelligence can play a role in overcoming some of the challenges and limitations; through data-guided metabolic flux optimization, and by systematically increasing the growth of the microalgae strains without negative outcomes, such as toxicity. This requires microalgae databases rich in omics data and further developments on its mining and analytics methods.
Collapse
Affiliation(s)
- Mohamed Helmy
- Bioinformatics Institute, Agency for Science, Technology and Research (A∗STAR), Singapore; Department of Computer Science, Lakehead University, Ontario, Canada
| | - Hosam Elhalis
- Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A∗STAR), Singapore, Singapore
| | - Yan Liu
- Institute of Sustainability for Chemistry, Energy and Environment (ISCE(2)), Agency for Science, Technology and Research (A∗STAR), Singapore, Singapore
| | - Yvonne Chow
- Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A∗STAR), Singapore, Singapore
| | - Kumar Selvarajoo
- Bioinformatics Institute, Agency for Science, Technology and Research (A∗STAR), Singapore; Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A∗STAR), Singapore, Singapore; Synthetic Biology for Clinical and Technological Innovation, National University of Singapore, Singapore, Singapore; School of Biological Sciences, Nanyang Technological University, Singapore.
| |
Collapse
|
3
|
Construction of a Rhodobacter sphaeroides Strain That Efficiently Produces Hydrogen Gas from Acetate without Poly(β-Hydroxybutyrate) Accumulation: Insight into the Role of PhaR in Acetate Metabolism. Appl Environ Microbiol 2022; 88:e0050722. [PMID: 35670584 DOI: 10.1128/aem.00507-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The purple nonsulfur phototrophic bacterium Rhodobacter sphaeroides produces hydrogen gas (H2) from acetate. An approach to improve the H2 production is preventing accumulation of an intracellular energy storage molecule known as poly(β-hydroxybutyrate) (PHB), which competes with H2 production for reducing power. However, disruption of PHB biosynthesis has been reported to severely impair the acetate assimilation depending on the genetic backgrounds and/or culture conditions. To solve this problem, we analyzed the relationship between PHB accumulation and acetate metabolism in R. sphaeroides. Gene deletion analyses based on the wild-type strain revealed that among the two polyhydroxyalkanoate synthase genes in the genome, phaC1, but not phaC2, is essential for PHB accumulation, and the phaC1 deletion mutant exhibited slow growth with acetate. On the other hand, a strain with the deletion of phaC1 together with phaR, which encodes a transcriptional regulator capable of sensing PHB accumulation, exhibited growth comparable to that of the wild-type strain despite no accumulation of PHB. These results suggest that PHB accumulation is required for normal growth with acetate by altering the expression of genes under the control of phaR. This hypothesis was supported by a transcriptome sequencing (RNA-seq) analysis revealing that phaR is involved in the regulation of the ethylmalonyl coenzyme A pathway for acetate assimilation. Consistent with these findings, deletion of phaC1 in a genetically engineered H2-producing strain resulted in lower H2 production from acetate due to growth defects, whereas deletion of phaR together with phaC1 restored growth with acetate and increased H2 production from acetate without PHB accumulation. IMPORTANCE This study provides a novel approach for increasing the yield of photofermentative H2 production from acetate by purple nonsulfur phototrophic bacteria. This study further suggests that polyhydroxyalkanoate is not only a storage substance for carbon and energy in bacteria, but may also act as a signaling molecule that mediates bacterial metabolic adaptations to specific environments. This notion will be helpful for understanding the physiology of polyhydroxyalkanoate-producing bacteria, as well as for their metabolic engineering via synthetic biology.
Collapse
|
4
|
Fitriana HN, Lee S, Kim HS, Lee J, Lee Y, Lee JS, Park H, Ko CH, Lim SY, Lee SY. Enhanced CO 2 electroconversion of Rhodobacter sphaeroides by cobalt-phosphate complex assisted water oxidation. Bioelectrochemistry 2022; 145:108102. [PMID: 35338862 DOI: 10.1016/j.bioelechem.2022.108102] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 03/10/2022] [Accepted: 03/18/2022] [Indexed: 01/02/2023]
Abstract
CO2 can be a next generation feedstock for electricity-driven bioproduction due to its abundance and availability. Microbial electrosynthesis (MES), a promising technique for CO2 electroconversion, provides an attractive route for the production of valuable products from CO2, but issues surrounding efficiency and reasonable productivity should be resolved. Improving the anode performance for water oxidation under neutral pH is one of the most important aspects to advance current MES. Here, we introduce cobalt-phosphate (Co-Pi) assisted water oxidation at the counter electrode (i.e., anode) to upgrade the MES performance at pH 7.0. We show that CO2 can be converted by photochemoautotrophic bacterium, Rhodobacter sphaeroides into organic acids and carotenoids in the MES reactor. Planktonic cells of R. sphareroides in the Co-Pi anode equipped MES reactor was ca. 1.5-fold higher than in the control condition (w/o Co-Pi). The faradaic efficiency of the Co-Pi anode equipped MES reactor was remarkably higher (58.3%) than that of the bare anode (27.8%). While the system can improve the CO2 electroconversion nonetheless there are some further optimizations are necessary.
Collapse
Affiliation(s)
- Hana Nur Fitriana
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, 61003 Gwangju, South Korea
| | - Sangmin Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, 61003 Gwangju, South Korea
| | - Hui Su Kim
- Department of Advanced Chemicals & Engineering, Chonnam National University, 61186 Gwangju, South Korea
| | - Jiye Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, 61003 Gwangju, South Korea
| | - Yurim Lee
- Interdisciplinary Program of Agriculture and Life Science, Chonnam National University, 61186 Gwangju, South Korea
| | - Jin-Suk Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, 61003 Gwangju, South Korea
| | - Hyojung Park
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, 61003 Gwangju, South Korea; Bioremediation Team, National Institute of Agricultural Sciences, 55365 Jeollabuk-do, South Korea
| | - Chang Hyun Ko
- Department of Advanced Chemicals & Engineering, Chonnam National University, 61186 Gwangju, South Korea; School of Chemical Engineering, Chonnam National University, 61186 Gwangju, South Korea
| | - Sung Yul Lim
- Department of Chemistry, Kyung Hee University, 02447 Seoul, South Korea
| | - Soo Youn Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, 61003 Gwangju, South Korea.
| |
Collapse
|
5
|
Surface Modification of a Graphite Felt Cathode with Amide-Coupling Enhances the Electron Uptake of Rhodobacter sphaeroides. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11167585] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microbial electrosynthesis (MES) is a promising technology platform for the production of chemicals and fuels from CO2 and external conducting materials (i.e., electrodes). In this system, electroactive microorganisms, called electrotrophs, serve as biocatalysts for cathodic reaction. While several CO2-fixing microorganisms can reduce CO2 to a variety of organic compounds by utilizing electricity as reducing energy, direct extracellular electron uptake is indispensable to achieve highly energy-efficient reaction. In the work reported here, Rhodobacter sphaeroides, a CO2-fixing chemoautotroph and a potential electroactive bacterium, was adopted to perform a cathodic CO2 reduction reaction via MES. To promote direct electron uptake, the graphite felt cathode was modified with a combination of chitosan and carbodiimide compound. Robust biofilm formation promoted by amide functionality between R. sphaeroides and a graphite felt cathode showed significantly higher faradaic efficiency (98.0%) for coulomb to biomass and succinic acid production than those of the bare (34%) and chitosan-modified graphite cathode (77.8%), respectively. The results suggest that cathode modification using a chitosan/carbodiimide composite may facilitate electron utilization by improving direct contact between an electrode and R. sphaeroides.
Collapse
|
6
|
Orsi E, Beekwilder J, Eggink G, Kengen SWM, Weusthuis RA. The transition of Rhodobacter sphaeroides into a microbial cell factory. Biotechnol Bioeng 2020; 118:531-541. [PMID: 33038009 PMCID: PMC7894463 DOI: 10.1002/bit.27593] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/29/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022]
Abstract
Microbial cell factories are the workhorses of industrial biotechnology and improving their performances can significantly optimize industrial bioprocesses. Microbial strain engineering is often employed for increasing the competitiveness of bio‐based product synthesis over more classical petroleum‐based synthesis. Recently, efforts for strain optimization have been standardized within the iterative concept of “design‐build‐test‐learn” (DBTL). This approach has been successfully employed for the improvement of traditional cell factories like Escherichia coli and Saccharomyces cerevisiae. Within the past decade, several new‐to‐industry microorganisms have been investigated as novel cell factories, including the versatile α‐proteobacterium Rhodobacter sphaeroides. Despite its history as a laboratory strain for fundamental studies, there is a growing interest in this bacterium for its ability to synthesize relevant compounds for the bioeconomy, such as isoprenoids, poly‐β‐hydroxybutyrate, and hydrogen. In this study, we reflect on the reasons for establishing R. sphaeroides as a cell factory from the perspective of the DBTL concept. Moreover, we discuss current and future opportunities for extending the use of this microorganism for the bio‐based economy. We believe that applying the DBTL pipeline for R. sphaeroides will further strengthen its relevance as a microbial cell factory. Moreover, the proposed use of strain engineering via the DBTL approach may be extended to other microorganisms that have not been critically investigated yet for industrial applications.
Collapse
Affiliation(s)
- Enrico Orsi
- Bioprocess Engineering, Wageningen University, Wageningen, The Netherlands.,Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | | | - Gerrit Eggink
- Bioprocess Engineering, Wageningen University, Wageningen, The Netherlands.,Wageningen Food and Biobased Research, Wageningen, The Netherlands
| | - Servé W M Kengen
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
| | - Ruud A Weusthuis
- Bioprocess Engineering, Wageningen University, Wageningen, The Netherlands
| |
Collapse
|
7
|
Biological insights into non-model microbial hosts through stable-isotope metabolic flux analysis. Curr Opin Biotechnol 2020; 64:32-38. [DOI: 10.1016/j.copbio.2019.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 12/16/2022]
|
8
|
Metabolic flux ratio analysis by parallel 13C labeling of isoprenoid biosynthesis in Rhodobacter sphaeroides. Metab Eng 2019; 57:228-238. [PMID: 31843486 DOI: 10.1016/j.ymben.2019.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/02/2019] [Accepted: 12/12/2019] [Indexed: 11/21/2022]
Abstract
Metabolic engineering for increased isoprenoid production often benefits from the simultaneous expression of the two naturally available isoprenoid metabolic routes, namely the 2-methyl-D-erythritol 4-phosphate (MEP) pathway and the mevalonate (MVA) pathway. Quantification of the contribution of these pathways to the overall isoprenoid production can help to obtain a better understanding of the metabolism within a microbial cell factory. Such type of investigation can benefit from 13C metabolic flux ratio studies. Here, we designed a method based on parallel labeling experiments (PLEs), using [1-13C]- and [4-13C]glucose as tracers to quantify the metabolic flux ratios in the glycolytic and isoprenoid pathways. By just analyzing a reporter isoprenoid molecule and employing only four equations, we could describe the metabolism involved from substrate catabolism to product formation. These equations infer 13C atom incorporation into the universal isoprenoid building blocks, isopentenyl-pyrophosphate (IPP) and dimethylallyl-pyrophosphate (DMAPP). Therefore, this renders the method applicable to the study of any of isoprenoid of interest. As proof of principle, we applied it to study amorpha-4,11-diene biosynthesis in the bacterium Rhodobacter sphaeroides. We confirmed that in this species the Entner-Doudoroff pathway is the major pathway for glucose catabolism, while the Embden-Meyerhof-Parnas pathway contributes to a lesser extent. Additionally, we demonstrated that co-expression of the MEP and MVA pathways caused a mutual enhancement of their metabolic flux capacity. Surprisingly, we also observed that the isoprenoid flux ratio remains constant under exponential growth conditions, independently from the expression level of the MVA pathway. Apart from proposing and applying a tool for studying isoprenoid biosynthesis within a microbial cell factory, our work reveals important insights from the co-expression of MEP and MVA pathways, including the existence of a yet unclear interaction between them.
Collapse
|
9
|
Orsi E, Folch PL, Monje-López VT, Fernhout BM, Turcato A, Kengen SWM, Eggink G, Weusthuis RA. Characterization of heterotrophic growth and sesquiterpene production by Rhodobacter sphaeroides on a defined medium. J Ind Microbiol Biotechnol 2019; 46:1179-1190. [PMID: 31187318 PMCID: PMC6697705 DOI: 10.1007/s10295-019-02201-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/29/2019] [Indexed: 11/30/2022]
Abstract
Rhodobacter sphaeroides is a metabolically versatile bacterium capable of producing terpenes natively. Surprisingly, terpene biosynthesis in this species has always been investigated in complex media, with unknown compounds possibly acting as carbon and nitrogen sources. Here, a defined medium was adapted for R. sphaeroides dark heterotrophic growth, and was used to investigate the conversion of different organic substrates into the reporter terpene amorphadiene. The amorphadiene synthase was cloned in R. sphaeroides, allowing its biosynthesis via the native 2-methyl-d-erythritol-4-phosphate (MEP) pathway and, additionally, via a heterologous mevalonate one. The latter condition increased titers up to eightfold. Consequently, better yields and productivities to previously reported complex media cultivations were achieved. Productivity was further investigated under different cultivation conditions, including nitrogen and oxygen availability. This novel cultivation setup provided useful insight into the understanding of terpene biosynthesis in R. sphaeroides, allowing to better comprehend its dynamics and regulation during chemoheterotrophic cultivation.
Collapse
Affiliation(s)
- Enrico Orsi
- Bioprocess Engineering, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands
| | - Pauline L Folch
- Bioprocess Engineering, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands
| | - Vicente T Monje-López
- Bioprocess Engineering, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands
| | - Bas M Fernhout
- Bioprocess Engineering, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands
| | - Alessandro Turcato
- Bioprocess Engineering, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands
| | - Servé W M Kengen
- Laboratory of Microbiology, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands
| | - Gerrit Eggink
- Bioprocess Engineering, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands.,Biobased Products Food and Biobased Research, Wageningen University and Research, Wageningen, The Netherlands
| | - Ruud A Weusthuis
- Bioprocess Engineering, Department of Agrotechnology and Food, Wageningen University and Research, Wageningen, The Netherlands.
| |
Collapse
|
10
|
Correia DM, Sargo CR, Silva AJ, Santos ST, Giordano RC, Ferreira EC, Zangirolami TC, Ribeiro MPA, Rocha I. Mapping Salmonella typhimurium pathways using 13C metabolic flux analysis. Metab Eng 2019; 52:303-314. [PMID: 30529284 DOI: 10.1016/j.ymben.2018.11.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 11/26/2018] [Accepted: 11/28/2018] [Indexed: 12/20/2022]
Abstract
In the last years, Salmonella has been extensively studied not only due to its importance as a pathogen, but also as a host to produce pharmaceutical compounds. However, the full exploitation of Salmonella as a platform for bioproduct delivery has been hampered by the lack of information about its metabolism. Genome-scale metabolic models can be valuable tools to delineate metabolic engineering strategies as long as they closely represent the actual metabolism of the target organism. In the present study, a 13C-MFA approach was applied to map the fluxes at the central carbon pathways of S. typhimurium LT2 growing at glucose-limited chemostat cultures. The experiments were carried out in a 2L bioreactor, using defined medium enriched with 20% 13C-labeled glucose. Metabolic flux distributions in central carbon pathways of S. typhimurium LT2 were estimated using OpenFLUX2 based on the labeling pattern of biomass protein hydrolysates together with biomass composition. The results suggested that pentose phosphate is used to catabolize glucose, with minor fluxes through glycolysis. In silico simulations, using Optflux and pFBA as simulation method, allowed to study the performance of the genome-scale metabolic model. In general, the accuracy of in silico simulations was improved by the superimposition of estimated intracellular fluxes to the existing genome-scale metabolic model, showing a better fitting to the experimental extracellular fluxes, whereas the intracellular fluxes of pentose phosphate and anaplerotic reactions were poorly described.
Collapse
Affiliation(s)
- Daniela M Correia
- Graduate Program of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil
| | - Cintia R Sargo
- Graduate Program of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil
| | - Adilson J Silva
- Graduate Program of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil
| | - Sophia T Santos
- CEB-Centre of Biological Engineering, University of Minho, Campus De Gualtar, Braga 4710-057, Portugal
| | - Roberto C Giordano
- Graduate Program of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil
| | - Eugénio C Ferreira
- CEB-Centre of Biological Engineering, University of Minho, Campus De Gualtar, Braga 4710-057, Portugal
| | - Teresa C Zangirolami
- Graduate Program of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil
| | - Marcelo P A Ribeiro
- Graduate Program of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil
| | - Isabel Rocha
- CEB-Centre of Biological Engineering, University of Minho, Campus De Gualtar, Braga 4710-057, Portugal; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB-NOVA), Oeiras, Portugal.
| |
Collapse
|
11
|
Introduction of Glyoxylate Bypass Increases Hydrogen Gas Yield from Acetate and l-Glutamate in Rhodobacter sphaeroides. Appl Environ Microbiol 2019; 85:AEM.01873-18. [PMID: 30413472 DOI: 10.1128/aem.01873-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/05/2018] [Indexed: 11/20/2022] Open
Abstract
Rhodobacter sphaeroides produces hydrogen gas (H2) from organic compounds via nitrogenase under anaerobic-light conditions in the presence of poor nitrogen sources, such as l-glutamate. R. sphaeroides utilizes the ethylmalonyl-coenzyme A (EMC) pathway for acetate assimilation, but its H2 yield from acetate in the presence of l-glutamate has been reported to be low. In this study, the deletion of ccr encoding crotonyl-coenzyme A (crotonyl-CoA) carboxylase/reductase, a key enzyme for the EMC pathway in R. sphaeroides, revealed that the EMC pathway is essential for H2 production from acetate and l-glutamate but not for growth and acetate consumption in the presence of l-glutamate. We introduced a plasmid expressing aceBA from Rhodobacter capsulatus encoding two key enzymes for the glyoxylate bypass into R. sphaeroides, which resulted in a 64% increase in H2 production. However, compared with the wild-type strain expressing heterologous aceBA genes, the strain with aceBA introduced in the genetic background of an EMC pathway-disrupted mutant showed a lower H2 yield. These results indicate that a combination of the endogenous EMC pathway and a heterologously expressed glyoxylate bypass is beneficial for H2 production. In addition, introduction of the glyoxylate bypass into a polyhydroxybutyrate (PHB) biosynthesis-disrupted mutant resulted in a delay in growth along with H2 production, although its H2 yield was comparable to that of the wild-type strain expressing heterologous aceBA genes. These results suggest that PHB production is important for fitness to the culture during H2 production from acetate and l-glutamate when both acetate-assimilating pathways are present.IMPORTANCE As an alternative to fossil fuel, H2 is a promising renewable energy source. Although photofermentative H2 production from acetate is key to developing an efficient process of biohydrogen production from biomass-derived sugars, H2 yields from acetate and l-glutamate by R. sphaeroides have been reported to be low. In this study, we observed that in addition to the endogenous EMC pathway, heterologous expression of the glyoxylate bypass in R. sphaeroides markedly increased H2 yields from acetate and l-glutamate. Therefore, this study provides a novel strategy for improving H2 yields from acetate in the presence of l-glutamate and contributes to a clear understanding of acetate metabolism in R. sphaeroides during photofermentative H2 production.
Collapse
|
12
|
Jagadevan S, Banerjee A, Banerjee C, Guria C, Tiwari R, Baweja M, Shukla P. Recent developments in synthetic biology and metabolic engineering in microalgae towards biofuel production. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:185. [PMID: 29988523 PMCID: PMC6026345 DOI: 10.1186/s13068-018-1181-1] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/20/2018] [Indexed: 05/03/2023]
Abstract
In the wake of the uprising global energy crisis, microalgae have emerged as an alternate feedstock for biofuel production. In addition, microalgae bear immense potential as bio-cell factories in terms of producing key chemicals, recombinant proteins, enzymes, lipid, hydrogen and alcohol. Abstraction of such high-value products (algal biorefinery approach) facilitates to make microalgae-based renewable energy an economically viable option. Synthetic biology is an emerging field that harmoniously blends science and engineering to help design and construct novel biological systems, with an aim to achieve rationally formulated objectives. However, resources and tools used for such nuclear manipulation, construction of synthetic gene network and genome-scale reconstruction of microalgae are limited. Herein, we present recent developments in the upcoming field of microalgae employed as a model system for synthetic biology applications and highlight the importance of genome-scale reconstruction models and kinetic models, to maximize the metabolic output by understanding the intricacies of algal growth. This review also examines the role played by microalgae as biorefineries, microalgal culture conditions and various operating parameters that need to be optimized to yield biofuel that can be economically competitive with fossil fuels.
Collapse
Affiliation(s)
- Sheeja Jagadevan
- Department of Environmental Science and Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand 826004 India
| | - Avik Banerjee
- Department of Environmental Science and Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand 826004 India
| | - Chiranjib Banerjee
- Department of Environmental Science and Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand 826004 India
| | - Chandan Guria
- Department of Environmental Science and Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand 826004 India
| | - Rameshwar Tiwari
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana 124001 India
- Enzyme and Microbial Biochemistry Lab, Department of Chemistry, Indian Institute of Technology, Hauz-Khas, New Delhi 110016 India
| | - Mehak Baweja
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana 124001 India
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana 124001 India
| |
Collapse
|
13
|
Azizan KA, Ressom HW, Mendoza ER, Baharum SN. 13C based proteinogenic amino acid (PAA) and metabolic flux ratio analysis of Lactococcus lactis reveals changes in pentose phosphate (PP) pathway in response to agitation and temperature related stresses. PeerJ 2017; 5:e3451. [PMID: 28695065 PMCID: PMC5501154 DOI: 10.7717/peerj.3451] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 05/19/2017] [Indexed: 11/20/2022] Open
Abstract
Lactococcus lactis subsp. cremoris MG1363 is an important starter culture for dairy fermentation. During industrial fermentations, L. lactis is constantly exposed to stresses that affect the growth and performance of the bacterium. Although the response of L. lactis to several stresses has been described, the adaptation mechanisms at the level of in vivo fluxes have seldom been described. To gain insights into cellular metabolism, 13C metabolic flux analysis and gas chromatography mass spectrometry (GC-MS) were used to measure the flux ratios of active pathways in the central metabolism of L. lactis when subjected to three conditions varying in temperature (30°C, 37°C) and agitation (with and without agitation at 150 rpm). Collectively, the concentrations of proteinogenic amino acids (PAAs) and free fatty acids (FAAs) were compared, and Pearson correlation analysis (r) was calculated to measure the pairwise relationship between PAAs. Branched chain and aromatic amino acids, threonine, serine, lysine and histidine were correlated strongly, suggesting changes in flux regulation in glycolysis, the pentose phosphate (PP) pathway, malic enzyme and anaplerotic reaction catalysed by pyruvate carboxylase (pycA). Flux ratio analysis revealed that glucose was mainly converted by glycolysis, highlighting the stability of L. lactis’ central carbon metabolism despite different conditions. Higher flux ratios through oxaloacetate (OAA) from pyruvate (PYR) reaction in all conditions suggested the activation of pyruvate carboxylate (pycA) in L. lactis, in response to acid stress during exponential phase. Subsequently, more significant flux ratio differences were seen through the oxidative and non-oxidative pentose phosphate (PP) pathways, malic enzyme, and serine and C1 metabolism, suggesting NADPH requirements in response to environmental stimuli. These reactions could play an important role in optimization strategies for metabolic engineering in L. lactis. Overall, the integration of systematic analysis of amino acids and flux ratio analysis provides a systems-level understanding of how L. lactis regulates central metabolism under various conditions.
Collapse
Affiliation(s)
- Kamalrul Azlan Azizan
- Metabolomics Research Laboratory, Institute of Systems Biology (INBIOSIS), Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor, Malaysia
| | - Habtom W Ressom
- Departments of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Eduardo R Mendoza
- Institute of Mathematics, University of the Philippines Diliman, Quezon City, Metro Manila, Philippines.,Membrane Biochemistry Group, Max Planck Institute of Biochemistry, Planegg, Germany
| | - Syarul Nataqain Baharum
- Metabolomics Research Laboratory, Institute of Systems Biology (INBIOSIS), Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor, Malaysia
| |
Collapse
|
14
|
Wei W, Liu T, Li X, Wang R, Zhao W, Zhao G, Zhao S, Zhou Z. Lysine acetylation regulates the function of the global anaerobic transcription factor FnrL in Rhodobacter sphaeroides. Mol Microbiol 2017; 104:278-293. [PMID: 28118511 DOI: 10.1111/mmi.13627] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2017] [Indexed: 01/04/2023]
Abstract
The metabolism of the purple non-sulfur bacterium Rhodobacter sphaeroides is versatile and it can grow under various conditions. Here, we report evidence that the anaerobic photosynthetic metabolism of R. sphaeroides is regulated by protein lysine acetylation. Using a proteomic approach, 59 acetylated peptides were detected. Among them is the global anaerobic transcription factor FnrL, which regulates the biosynthetic pathway of tetrapyrroles and synthesis of the photosynthetic apparatus. Lysine 223 of FnrL was identified as acetylated. We show that all three lysines in the DNA binding domain (K223, K213 and K175) of FnrL can be acetylated by acetyl-phosphate in vitro. A bacterial deacetylase homolog, RsCobB can deacetylate FnrL in vitro. The transcription of genes downstream of FnrL decreased when the DNA binding domain of FnrL was acetylated, as revealed by chromatin immunoprecipitation and acetylation-mimicking mutagenesis. An increasing number of acetylated lysines resulted in a further decrease in DNA binding ability. These results demonstrate that the lysine acetylation can fine tune the function of the oxygen-sensitive FnrL; thus, it might regulate anaerobic photosynthetic metabolism of R. sphaeroides.
Collapse
Affiliation(s)
- Wei Wei
- CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Tong Liu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan, 650091, China
| | - Xinfeng Li
- CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Ruofan Wang
- CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Wei Zhao
- CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Guoping Zhao
- CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Shimin Zhao
- State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences and Institute of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Zhihua Zhou
- CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| |
Collapse
|
15
|
Chen C, Hong M, Chu J, Huang M, Ouyang L, Tian X, Zhuang Y. Blocking the flow of propionate into TCA cycle through a mutB knockout leads to a significant increase of erythromycin production by an industrial strain of Saccharopolyspora erythraea. Bioprocess Biosyst Eng 2016; 40:201-209. [DOI: 10.1007/s00449-016-1687-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 09/23/2016] [Indexed: 11/28/2022]
|
16
|
Yang C, Gao X, Jiang Y, Sun B, Gao F, Yang S. Synergy between methylerythritol phosphate pathway and mevalonate pathway for isoprene production in Escherichia coli. Metab Eng 2016; 37:79-91. [DOI: 10.1016/j.ymben.2016.05.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/21/2016] [Accepted: 05/05/2016] [Indexed: 01/08/2023]
|
17
|
Krasil’nikova EN, Ivanovsky RN, Keppen OI, Lebedeva NV. Carbohydrate metabolism of the phase variants of purple photosynthetic bacteria. Microbiology (Reading) 2016. [DOI: 10.1134/s0026261716030061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
18
|
Xie X, Huang A, Gu W, Zang Z, Pan G, Gao S, He L, Zhang B, Niu J, Lin A, Wang G. Photorespiration participates in the assimilation of acetate in Chlorella sorokiniana under high light. THE NEW PHYTOLOGIST 2016; 209:987-998. [PMID: 26439434 DOI: 10.1111/nph.13659] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 08/17/2015] [Indexed: 06/05/2023]
Abstract
The development of microalgae on an industrial scale largely depends on the economic feasibility of mass production. High light induces productive suspensions during cultivation in a tubular photobioreactor. Herein, we report that high light, which inhibited the growth of Chlorella sorokiniana under autotrophic conditions, enhanced the growth of this alga in the presence of acetate. We compared pigments, proteomics and the metabolic flux ratio in C. sorokiniana cultivated under high light (HL) and under low light (LL) in the presence of acetate. Our results showed that high light induced the synthesis of xanthophyll and suppressed the synthesis of chlorophylls. Acetate in the medium was exhausted much more rapidly in HL than in LL. The data obtained from LC-MS/MS indicated that high light enhanced photorespiration, the Calvin cycle and the glyoxylate cycle of mixotrophic C. sorokiniana. The results of metabolic flux ratio analysis showed that the majority of the assimilated carbon derived from supplemented acetate, and photorespiratory glyoxylate could enter the glyoxylate cycle. Based on these data, we conclude that photorespiration provides glyoxylate to speed up the glyoxylate cycle, and releases acetate-derived CO2 for the Calvin cycle. Thus, photorespiration connects the glyoxylate cycle and the Calvin cycle, and participates in the assimilation of supplemented acetate in C. sorokiniana under high light.
Collapse
Affiliation(s)
- Xiujun Xie
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
- Tianjin Key Laboratory of Marine Resources and Chemistry, College of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Aiyou Huang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Wenhui Gu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Zhengrong Zang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Guanghua Pan
- Tianjin Key Laboratory of Marine Resources and Chemistry, College of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Shan Gao
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Linwen He
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Baoyu Zhang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Jianfeng Niu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Apeng Lin
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Guangce Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| |
Collapse
|
19
|
Huang A, Liu L, Zhao P, Yang C, Wang GC. Metabolic flux ratio analysis and cell staining suggest the existence of C4 photosynthesis in Phaeodactylum tricornutum. J Appl Microbiol 2015; 120:705-13. [PMID: 26661799 DOI: 10.1111/jam.13020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 08/15/2015] [Accepted: 09/21/2015] [Indexed: 12/20/2022]
Abstract
AIMS Mechanisms for carbon fixation via photosynthesis in the diatom Phaeodactylum tricornutum Bohlin were studied recently but there remains a long-standing debate concerning the occurrence of C4 photosynthesis in this species. A thorough investigation of carbon metabolism and the evidence for C4 photosynthesis based on organelle partitioning was needed. METHODS AND RESULTS In this study, we identified the flux ratios between C3 and C4 compounds in P. tricornutum using (13)C-labelling metabolic flux ratio analysis, and stained cells with various cell-permeant fluorescent probes to investigate the likely organelle partitioning required for single-cell C4 photosynthesis. Metabolic flux ratio analysis indicated the C3/C4 exchange ratios were high. Cell staining indicated organelle partitioning required for single-cell C4 photosynthesis might exist in P. tricornutum. CONCLUSION The results of (13)C-labelling metabolic flux ratio analysis and cell staining suggest single-cell C4 photosynthesis exists in P. tricornutum. SIGNIFICANCE AND IMPACT OF THE STUDY This study provides insights into photosynthesis patterns of P. tricornutum and the evidence for C4 photosynthesis based on (13)C-labelling metabolic flux ratio analysis and organelle partitioning.
Collapse
Affiliation(s)
- A Huang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Science, Qingdao, Shandong, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - L Liu
- Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - P Zhao
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Science, Qingdao, Shandong, China
| | - C Yang
- Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - G C Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Science, Qingdao, Shandong, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| |
Collapse
|
20
|
Farmer RM, Tabita FR. Phosphoribulokinase mediates nitrogenase-induced carbon dioxide fixation gene repression in Rhodobacter sphaeroides. MICROBIOLOGY-SGM 2015; 161:2184-91. [PMID: 26306848 PMCID: PMC4806589 DOI: 10.1099/mic.0.000160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In many organisms there is a balance between carbon and nitrogen metabolism. These observations extend to the nitrogen-fixing, nonsulfur purple bacteria, which have the classic family of P(II) regulators that coordinate signals of carbon and nitrogen status to regulate nitrogen metabolism. Curiously, these organisms also possess a reverse mechanism to regulate carbon metabolism based on cellular nitrogen status. In this work, studies in Rhodobacter sphaeroides firmly established that the activity of the enzyme that catalyses nitrogen fixation, nitrogenase, induces a signal that leads to repression of genes encoding enzymes of the Calvin–Benson–Bassham (CBB) CO2 fixation pathway. Additionally, genetic and metabolomic experiments revealed that NADH-activated phosphoribulokinase is an intermediate in the signalling pathway. Thus, nitrogenase activity appears to be linked to cbb gene repression through phosphoribulokinase.
Collapse
Affiliation(s)
- Ryan M Farmer
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| |
Collapse
|
21
|
Cheng D, Wang R, Prather KJ, Chow KL, Hsing IM. Tackling codon usage bias for heterologous expression in Rhodobacter sphaeroides by supplementation of rare tRNAs. Enzyme Microb Technol 2015; 72:25-34. [DOI: 10.1016/j.enzmictec.2015.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/05/2015] [Accepted: 02/07/2015] [Indexed: 10/24/2022]
|
22
|
Kim DH, Lee JH, Kang S, Hallenbeck PC, Kim EJ, Lee JK, Kim MS. Enhanced photo-fermentative H2 production using Rhodobacter sphaeroides by ethanol addition and analysis of soluble microbial products. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:79. [PMID: 24883103 PMCID: PMC4038723 DOI: 10.1186/1754-6834-7-79] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 05/09/2014] [Indexed: 05/30/2023]
Abstract
BACKGROUND Biological fermentation routes can provide an environmentally friendly way of producing H2 since they use renewable biomass as feedstock and proceed under ambient temperature and pressure. In particular, photo-fermentation has superior properties in terms of achieving high H2 yield through complete degradation of substrates. However, long-term H2 production data with stable performance is limited, and this data is essential for practical applications. In the present work, continuous photo-fermentative H2 production from lactate was attempted using the purple non-sulfur bacterium, Rhodobacter sphaeroides KD131. As a gradual drop in H2 production was observed, we attempted to add ethanol (0.2% v/v) to the medium. RESULTS As continuous operation went on, H2 production was not sustained and showed a negligible H2 yield (< 0.5 mol H2/mol lactateadded) within two weeks. Electron balance analysis showed that the reason for the gradual drop in H2 production was ascribed to the increase in production of soluble microbial products (SMPs). To see the possible effect of ethanol addition, a batch test was first conducted. The presence of ethanol significantly increased the H2 yield from 1.15 to 2.20 mol H2/mol lactateadded, by suppressing the production of SMPs. The analysis of SMPs by size exclusion chromatography showed that, in the later period of fermentation, more than half of the low molecular weight SMPs (< 1 kDa) were consumed and used for H2 production when ethanol had been added, while the concentration of SMPs continuously increased in the absence of ethanol. It was found that the addition of ethanol facilitated the utilization of reducing power, resulting in an increase in the cellular levels of NAD(+) and NADP(+). In continuous operation, ethanol addition was effective, such that stable H2 production was attained with an H2 yield of 2.5 mol H2/mol lactateadded. Less than 15% of substrate electrons were used for SMP production, whereas 35% were used in the control. CONCLUSIONS We have found that SMPs are the key factor in photo-fermentative H2 production, and their production can be suppressed by ethanol addition. However, since external addition of ethanol to the medium represents an extra economic burden, ethanol should be prepared in a cost-effective way.
Collapse
Affiliation(s)
- Dong-Hoon Kim
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Daejeon, Yuseong-gu 305-343, Republic of Korea
| | - Ji-Hye Lee
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Daejeon, Yuseong-gu 305-343, Republic of Korea
| | - Seoktae Kang
- Department of Civil Engineering, Kyung Hee University, 1732 Deokyoungdaero, Yongin, Giheung, Gyeonggi-do 446-701, Republic of Korea
| | - Patrick C Hallenbeck
- Departement of Microbiology and Immunology, University of Montreal, CP 6128, Succursale Centre-Ville, Montreal, QC H3C 3J7, Canada
| | - Eui-Jin Kim
- Department of Life Science and Basic Science Institute for Cell Damage Control, Sogang University, Mapo, Shinsu 1, Seoul 121-742, Republic of Korea
| | - Jeong K Lee
- Department of Life Science and Basic Science Institute for Cell Damage Control, Sogang University, Mapo, Shinsu 1, Seoul 121-742, Republic of Korea
| | - Mi-Sun Kim
- Biomass and Waste Energy Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Daejeon, Yuseong-gu 305-343, Republic of Korea
- Division of Renewable Energy Engineering, University of Science and Technology, 217 Gajeong-ro, Daejeon, Yuseong-gu 305-350, Republic of Korea
| |
Collapse
|
23
|
Alagesan S, Gaudana SB, Sinha A, Wangikar PP. Metabolic flux analysis of Cyanothece sp. ATCC 51142 under mixotrophic conditions. PHOTOSYNTHESIS RESEARCH 2013; 118:191-198. [PMID: 23954952 DOI: 10.1007/s11120-013-9911-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/06/2013] [Indexed: 06/02/2023]
Abstract
Cyanobacteria are a group of photosynthetic prokaryotes capable of utilizing solar energy to fix atmospheric carbon dioxide to biomass. Despite several "proof of principle" studies, low product yield is an impediment in commercialization of cyanobacteria-derived biofuels. Estimation of intracellular reaction rates by (13)C metabolic flux analysis ((13)C-MFA) would be a step toward enhancing biofuel yield via metabolic engineering. We report (13)C-MFA for Cyanothece sp. ATCC 51142, a unicellular nitrogen-fixing cyanobacterium, known for enhanced hydrogen yield under mixotrophic conditions. Rates of reactions in the central carbon metabolism under nitrogen-fixing and -non-fixing conditions were estimated by monitoring the competitive incorporation of (12)C and (13)C from unlabeled CO2 and uniformly labeled glycerol, respectively, into terminal metabolites such as amino acids. The observed labeling patterns suggest mixotrophic growth under both the conditions, with a larger fraction of unlabeled carbon in nitrate-sufficient cultures asserting a greater contribution of carbon fixation by photosynthesis and an anaplerotic pathway. Indeed, flux analysis complements the higher growth observed under nitrate-sufficient conditions. On the other hand, the flux through the oxidative pentose phosphate pathway and tricarboxylic acid cycle was greater in nitrate-deficient conditions, possibly to supply the precursors and reducing equivalents needed for nitrogen fixation. In addition, an enhanced flux through fructose-6-phosphate phosphoketolase possibly suggests the organism's preferred mode under nitrogen-fixing conditions. The (13)C-MFA results complement the reported predictions by flux balance analysis and provide quantitative insight into the organism's distinct metabolic features under nitrogen-fixing and -non-fixing conditions.
Collapse
Affiliation(s)
- Swathi Alagesan
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | | | | | | |
Collapse
|
24
|
Metabolic flux analysis of Arthrobacter sp. CGMCC 3584 for cAMP production based on 13C tracer experiments and gas chromatography-mass spectrometry. J Biotechnol 2013; 168:355-61. [PMID: 24056081 DOI: 10.1016/j.jbiotec.2013.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 09/04/2013] [Accepted: 09/10/2013] [Indexed: 11/24/2022]
Abstract
Arthrobacter sp. CGMCC 3584 are able to produce cAMP from glucose by the purine synthesis pathway via de novo or salvage biosynthesis. In order to gain an improved understanding of its metabolism, (13)C-labeling experiment and gas chromatography-mass spectrometry (GC-MS) analysis were employed to determine the metabolic network structure and estimate the intracellular fluxes. GC-MS analysis helps to reflect the activity of the intracellular pathways and reactions. The metabolic network mainly contains glycolytic and pentose phosphate pathways, the tricarboxylic acid cycle, and the inactive glyoxylate shunt. Hypoxanthine as a precursor of cAMP and sodium fluoride as an inhibitor of glycolysis were found to increase the cAMP production, as well as the flux through the PP pathway. The effects of adding hypoxanthine and sodium fluoride are discussed based on the enzyme assays and metabolic flux analysis. In conclusion, our results provide quantitative insights into how cells manipulate the metabolic network under different culture conditions and this may be of value in metabolic regulation for desirable production.
Collapse
|
25
|
Hallenbeck PC, Abo-Hashesh M, Ghosh D. Strategies for improving biological hydrogen production. BIORESOURCE TECHNOLOGY 2012; 110:1-9. [PMID: 22342581 DOI: 10.1016/j.biortech.2012.01.103] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 01/15/2012] [Accepted: 01/19/2012] [Indexed: 05/21/2023]
Abstract
Biological hydrogen production presents a possible avenue for the large scale sustainable generation of hydrogen needed to fuel a future hydrogen economy. Amongst the possible approaches that are under active investigation and that will be briefly discussed; biophotolysis, photofermentation, microbial electrolysis, and dark fermentation, dark fermentation has the additional advantages of largely relying on already developed bioprocess technology and of potentially using various waste streams as feedstock. However, the major roadblock to developing a practical process has been the low yields, typically around 25%, well below those achievable for the production of other biofuels from the same feedstocks. Moreover, low yields also lead to the generation of side products whose large scale production would generate a waste disposal problem. Here recent attempts to overcome these barriers are reviewed and recent progress in efforts to increase hydrogen yields through physiological manipulation, metabolic engineering and the use of two-stage systems are described.
Collapse
Affiliation(s)
- Patrick C Hallenbeck
- Département de microbiologie et immunologie, Université de Montréal, CP 6128, Centre-ville, Montréal, Canada PQ H3C 3J7.
| | | | | |
Collapse
|