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Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production

BACKGROUND: The necessity to develop high lipid-producing microalgae is emphasized for the commercialization of microalgal biomass, which is environmentally friendly and sustainable. Nannochloropsis are one of the best industrial microalgae and have been widely studied for their lipids, including hi...

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Autores principales: Ryu, Ae Jin, Kang, Nam Kyu, Jeon, Seungjib, Hur, Dong Hoon, Lee, Eun Mi, Lee, Do Yup, Jeong, Byeong-ryool, Chang, Yong Keun, Jeong, Ki Jun
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7057510/
https://www.ncbi.nlm.nih.gov/pubmed/32158502
http://dx.doi.org/10.1186/s13068-020-01681-4
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author Ryu, Ae Jin
Kang, Nam Kyu
Jeon, Seungjib
Hur, Dong Hoon
Lee, Eun Mi
Lee, Do Yup
Jeong, Byeong-ryool
Chang, Yong Keun
Jeong, Ki Jun
author_facet Ryu, Ae Jin
Kang, Nam Kyu
Jeon, Seungjib
Hur, Dong Hoon
Lee, Eun Mi
Lee, Do Yup
Jeong, Byeong-ryool
Chang, Yong Keun
Jeong, Ki Jun
author_sort Ryu, Ae Jin
collection PubMed
description BACKGROUND: The necessity to develop high lipid-producing microalgae is emphasized for the commercialization of microalgal biomass, which is environmentally friendly and sustainable. Nannochloropsis are one of the best industrial microalgae and have been widely studied for their lipids, including high-value polyunsaturated fatty acids (PUFAs). Many reports on the genetic and biological engineering of Nannochloropsis to improve their growth and lipid contents have been published. RESULTS: We performed insertional mutagenesis in Nannochloropsis salina, and screened mutants with high lipid contents using fluorescence-activated cell sorting (FACS). We isolated a mutant, Mut68, which showed improved growth and a concomitant increase in lipid contents. Mut68 exhibited 53% faster growth rate and 34% higher fatty acid methyl ester (FAME) contents after incubation for 8 days, resulting in a 75% increase in FAME productivity compared to that in the wild type (WT). By sequencing the whole genome, we identified the disrupted gene in Mut68 that encoded trehalose-6-phosphate (T6P) synthase (TPS). TPS is composed of two domains: TPS domain and T6P phosphatase (TPP) domain, which catalyze the initial formation of T6P and dephosphorylation to trehalose, respectively. Mut68 was disrupted at the TPP domain in the C-terminal half, which was confirmed by metabolic analyses revealing a great reduction in the trehalose content in Mut68. Consistent with the unaffected N-terminal TPS domain, Mut68 showed moderate increase in T6P that is known for regulation of sugar metabolism, growth, and lipid biosynthesis. Interestingly, the metabolic analyses also revealed a significant increase in stress-related amino acids, including proline and glutamine, which may further contribute to the Mut68 phenotypes. CONCLUSION: We have successfully isolated an insertional mutant showing improved growth and lipid production. Moreover, we identified the disrupted gene encoding TPS. Consistent with the disrupted TPP domain, metabolic analyses revealed a moderate increase in T6P and greatly reduced trehalose. Herein, we provide an excellent proof of concept that the selection of insertional mutations via FACS can be employed for the isolation of mutants with improved growth and lipid production. In addition, trehalose and genes encoding TPS will provide novel targets for chemical and genetic engineering, in other microalgae and organisms as well as Nannochloropsis.
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spelling pubmed-70575102020-03-10 Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production Ryu, Ae Jin Kang, Nam Kyu Jeon, Seungjib Hur, Dong Hoon Lee, Eun Mi Lee, Do Yup Jeong, Byeong-ryool Chang, Yong Keun Jeong, Ki Jun Biotechnol Biofuels Research BACKGROUND: The necessity to develop high lipid-producing microalgae is emphasized for the commercialization of microalgal biomass, which is environmentally friendly and sustainable. Nannochloropsis are one of the best industrial microalgae and have been widely studied for their lipids, including high-value polyunsaturated fatty acids (PUFAs). Many reports on the genetic and biological engineering of Nannochloropsis to improve their growth and lipid contents have been published. RESULTS: We performed insertional mutagenesis in Nannochloropsis salina, and screened mutants with high lipid contents using fluorescence-activated cell sorting (FACS). We isolated a mutant, Mut68, which showed improved growth and a concomitant increase in lipid contents. Mut68 exhibited 53% faster growth rate and 34% higher fatty acid methyl ester (FAME) contents after incubation for 8 days, resulting in a 75% increase in FAME productivity compared to that in the wild type (WT). By sequencing the whole genome, we identified the disrupted gene in Mut68 that encoded trehalose-6-phosphate (T6P) synthase (TPS). TPS is composed of two domains: TPS domain and T6P phosphatase (TPP) domain, which catalyze the initial formation of T6P and dephosphorylation to trehalose, respectively. Mut68 was disrupted at the TPP domain in the C-terminal half, which was confirmed by metabolic analyses revealing a great reduction in the trehalose content in Mut68. Consistent with the unaffected N-terminal TPS domain, Mut68 showed moderate increase in T6P that is known for regulation of sugar metabolism, growth, and lipid biosynthesis. Interestingly, the metabolic analyses also revealed a significant increase in stress-related amino acids, including proline and glutamine, which may further contribute to the Mut68 phenotypes. CONCLUSION: We have successfully isolated an insertional mutant showing improved growth and lipid production. Moreover, we identified the disrupted gene encoding TPS. Consistent with the disrupted TPP domain, metabolic analyses revealed a moderate increase in T6P and greatly reduced trehalose. Herein, we provide an excellent proof of concept that the selection of insertional mutations via FACS can be employed for the isolation of mutants with improved growth and lipid production. In addition, trehalose and genes encoding TPS will provide novel targets for chemical and genetic engineering, in other microalgae and organisms as well as Nannochloropsis. BioMed Central 2020-03-05 /pmc/articles/PMC7057510/ /pubmed/32158502 http://dx.doi.org/10.1186/s13068-020-01681-4 Text en © The Author(s) 2020 Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
spellingShingle Research
Ryu, Ae Jin
Kang, Nam Kyu
Jeon, Seungjib
Hur, Dong Hoon
Lee, Eun Mi
Lee, Do Yup
Jeong, Byeong-ryool
Chang, Yong Keun
Jeong, Ki Jun
Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production
title Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production
title_full Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production
title_fullStr Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production
title_full_unstemmed Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production
title_short Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production
title_sort development and characterization of a nannochloropsis mutant with simultaneously enhanced growth and lipid production
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7057510/
https://www.ncbi.nlm.nih.gov/pubmed/32158502
http://dx.doi.org/10.1186/s13068-020-01681-4
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