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Khatiwada B, Sunna A, Nevalainen H. Molecular tools and applications of Euglena gracilis: From biorefineries to bioremediation. Biotechnol Bioeng 2020; 117:3952-3967. [PMID: 32710635 DOI: 10.1002/bit.27516] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 06/17/2020] [Accepted: 07/23/2020] [Indexed: 12/19/2022]
Abstract
Euglena gracilis is a promising source of commercially important metabolites such as vitamins, wax esters, paramylon, and amino acids. However, the molecular tools available to create improved Euglena strains are limited compared to other microorganisms that are currently exploited in the biotechnology industry. The complex poly-endosymbiotic nature of the Euglena genome is a major bottleneck for obtaining a complete genome sequence and thus represents a notable shortcoming in gaining molecular information of this organism. Therefore, the studies and applications have been more focused on using the wild-type strain or its variants and optimizing the nutrient composition and cultivation conditions to enhance the production of biomass and valuable metabolites. In addition to producing metabolites, the E. gracilis biorefinery concept also provides means for the production of biofuels and biogas as well as residual biomass for the remediation of industrial and municipal wastewater. Using Euglena for bioremediation of environments contaminated with heavy metals is of special interest due to the strong ability of the organism to accumulate and sequester these compounds. The published draft genome and transcriptome will serve as a basis for further molecular studies of Euglena and provide a guide for the engineering of metabolic pathways of relevance for the already established as well as novel applications.
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Affiliation(s)
- Bishal Khatiwada
- Department Molecular Sciences, Macquarie University, Sydney, Australia.,Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia
| | - Anwar Sunna
- Department Molecular Sciences, Macquarie University, Sydney, Australia.,Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia
| | - Helena Nevalainen
- Department Molecular Sciences, Macquarie University, Sydney, Australia.,Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia
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Chen H, Shen C, Chen Z, Hu J, Wen Y. Disturbance of chiral ionic liquids to phototaxis of Chlamydomonas reinhardtii: regular analysis and mechanism attempt. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:15011-15019. [PMID: 32067170 DOI: 10.1007/s11356-020-07882-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
Given the recent extensive synthesis and application of ionic liquids (ILs), finding a sensitive and visual indicator to provide a fast-initial risk assessment of IL use has become a pressing issue. In this study, we verified that the phototaxis of Chlamydomonas reinhardtii is a valid indicator of the environmental risk associated with chiral ILs L-(+)- and D-(-)-1-butyl-3-methylimidazolium lactate (BMIM L). Briefly, C. reinhardtii was exposed to a 4000-lx side light source for varying lengths of time. Following the allotted exposure time, the algae aggregation was photographed, and then quantitative analysis was conducted using Image-J software to obtain the corresponding relationship between IL stimulation and C. reinhardtii phototaxis. The gray areas from each treatment were measured and the percentage was calculated. After 16 h of side lighting, for control, the percentage of gray areas was - 22%, while for L-(+)- and D-(-)- BMIM L were 17% and 33%, respectively. Then, after 8 h of darkness, where D-(-)-BMIM L and the control showed the positive phototaxis, but the L-(+)-BMIM L-treated group showed virtually no change. This phenomenon is consistent with excessive production of reactive oxygen species (ROS). Moreover, atomic force microscope (AFM) results indicated distinct aggregation between D-(-)- and L-(+)-BMIM L, which caused changes in cell permeability that induced a change in ROS transfer. Furthermore, relationship between phototaxis and changes in cell ultrastructure and photosynthetic efficiency was also investigated. This work demonstrates the potential of phototaxis to serve as a sensitive, convenient, and cost effective qualitative assessment of ILs' toxic impact, with the understanding that quantitative evaluation requires further improvement.
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Affiliation(s)
- Hui Chen
- College of Science and Technology, Ningbo University, Ningbo, 315212, China
| | - Chensi Shen
- College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China
| | - Zunwei Chen
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, 77843, USA
| | - Jinxing Hu
- College of Science and Technology, Ningbo University, Ningbo, 315212, China
| | - Yuezhong Wen
- MOE Key Laboratory of Environmental Remediation & Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
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Guo B, Lei C, Kobayashi H, Ito T, Yalikun Y, Jiang Y, Tanaka Y, Ozeki Y, Goda K. High-throughput, label-free, single-cell, microalgal lipid screening by machine-learning-equipped optofluidic time-stretch quantitative phase microscopy. Cytometry A 2017; 91:494-502. [PMID: 28399328 DOI: 10.1002/cyto.a.23084] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 01/19/2017] [Accepted: 01/23/2017] [Indexed: 12/16/2022]
Abstract
The development of reliable, sustainable, and economical sources of alternative fuels to petroleum is required to tackle the global energy crisis. One such alternative is microalgal biofuel, which is expected to play a key role in reducing the detrimental effects of global warming as microalgae absorb atmospheric CO2 via photosynthesis. Unfortunately, conventional analytical methods only provide population-averaged lipid amounts and fail to characterize a diverse population of microalgal cells with single-cell resolution in a non-invasive and interference-free manner. Here high-throughput label-free single-cell screening of lipid-producing microalgal cells with optofluidic time-stretch quantitative phase microscopy was demonstrated. In particular, Euglena gracilis, an attractive microalgal species that produces wax esters (suitable for biodiesel and aviation fuel after refinement), within lipid droplets was investigated. The optofluidic time-stretch quantitative phase microscope is based on an integration of a hydrodynamic-focusing microfluidic chip, an optical time-stretch quantitative phase microscope, and a digital image processor equipped with machine learning. As a result, it provides both the opacity and phase maps of every single cell at a high throughput of 10,000 cells/s, enabling accurate cell classification without the need for fluorescent staining. Specifically, the dataset was used to characterize heterogeneous populations of E. gracilis cells under two different culture conditions (nitrogen-sufficient and nitrogen-deficient) and achieve the cell classification with an error rate of only 2.15%. The method holds promise as an effective analytical tool for microalgae-based biofuel production. © 2017 International Society for Advancement of Cytometry.
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Affiliation(s)
- Baoshan Guo
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan
| | - Cheng Lei
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan.,Department of Electronic Engineering, Tsinghua University, Beijing, 100084, China
| | | | - Takuro Ito
- Japan Science and Technology Agency, Kawaguchi, 332-0012, Japan
| | - Yaxiaer Yalikun
- Laboratory for Integrated Biodevices, Quantitative Biology Center, RIKEN, Osaka, 565-0871, Japan
| | - Yiyue Jiang
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan
| | - Yo Tanaka
- Laboratory for Integrated Biodevices, Quantitative Biology Center, RIKEN, Osaka, 565-0871, Japan
| | - Yasuyuki Ozeki
- Department of Electrical Engineering and Information Systems, University of Tokyo, Tokyo, 113-8656, Japan
| | - Keisuke Goda
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan.,Japan Science and Technology Agency, Kawaguchi, 332-0012, Japan.,Department of Electrical Engineering, University of California, Los Angeles, California, 90095
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Guo B, Lei C, Ito T, Jiang Y, Ozeki Y, Goda K. High-Throughput Accurate Single-Cell Screening of Euglena gracilis with Fluorescence-Assisted Optofluidic Time-Stretch Microscopy. PLoS One 2016; 11:e0166214. [PMID: 27846239 PMCID: PMC5112898 DOI: 10.1371/journal.pone.0166214] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/25/2016] [Indexed: 11/19/2022] Open
Abstract
The development of reliable, sustainable, and economical sources of alternative fuels is an important, but challenging goal for the world. As an alternative to liquid fossil fuels, algal biofuel is expected to play a key role in alleviating global warming since algae absorb atmospheric CO2 via photosynthesis. Among various algae for fuel production, Euglena gracilis is an attractive microalgal species as it is known to produce wax ester (good for biodiesel and aviation fuel) within lipid droplets. To date, while there exist many techniques for inducing microalgal cells to produce and accumulate lipid with high efficiency, few analytical methods are available for characterizing a population of such lipid-accumulated microalgae including E. gracilis with high throughout, high accuracy, and single-cell resolution simultaneously. Here we demonstrate high-throughput, high-accuracy, single-cell screening of E. gracilis with fluorescence-assisted optofluidic time-stretch microscopy-a method that combines the strengths of microfluidic cell focusing, optical time-stretch microscopy, and fluorescence detection used in conventional flow cytometry. Specifically, our fluorescence-assisted optofluidic time-stretch microscope consists of an optical time-stretch microscope and a fluorescence analyzer on top of a hydrodynamically focusing microfluidic device and can detect fluorescence from every E. gracilis cell in a population and simultaneously obtain its image with a high throughput of 10,000 cells/s. With the multi-dimensional information acquired by the system, we classify nitrogen-sufficient (ordinary) and nitrogen-deficient (lipid-accumulated) E. gracilis cells with a low false positive rate of 1.0%. This method holds promise for evaluating cultivation techniques and selective breeding for microalgae-based biofuel production.
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Affiliation(s)
- Baoshan Guo
- Department of Chemistry, University of Tokyo, Tokyo 113–0033, Japan
| | - Cheng Lei
- Department of Chemistry, University of Tokyo, Tokyo 113–0033, Japan
- Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
- * E-mail: (CL); (KG)
| | - Takuro Ito
- Japan Science and Technology Agency, Kawaguchi 332–0012, Japan
| | - Yiyue Jiang
- Department of Chemistry, University of Tokyo, Tokyo 113–0033, Japan
| | - Yasuyuki Ozeki
- Department of Electrical Engineering and Information Systems, University of Tokyo, Tokyo 113–8656, Japan
| | - Keisuke Goda
- Department of Chemistry, University of Tokyo, Tokyo 113–0033, Japan
- Japan Science and Technology Agency, Kawaguchi 332–0012, Japan
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California, 90095, United States of America
- * E-mail: (CL); (KG)
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