Comparative Profiling Analysis of Central Metabolites in<i>Euglena gracilis</i>under Various Cultivation Conditions

Mizutani, Fumio; Hayashi, Masahiro; Kondo, Akihiko

doi:10.1271/bbb.110482

Cited by 42 publications

(31 citation statements)

References 18 publications

(23 reference statements)

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“…Yoshida et al (2016) proposed E. gracilis uses fumarate, rather than O 2 , as an electron acceptor under anaerobic conditions; this agrees with our results showing that E. gracilis produced succinate during dark, anaerobic incubation ( Figure 3 ). Metabolomic analysis, conducted using the same strain of E. gracilis , shows that compared with the levels of metabolites in cells grown under light, aerobic conditions, the levels of pyruvate decreased to 4% in cells grown under dark, anaerobic conditions (Matsuda et al, 2011). The authors suggest that the decrease in pyruvate was related to the biosynthesis of wax ester, which is produced from acetyl-CoA (Matsuda et al, 2011); however, we suggest that the decreased pyruvate is also related to the production of succinate and lactate under dark, anaerobic conditions ( Figures 3 and 4 ).…”

Section: Discussionmentioning

confidence: 99%

Succinate and Lactate Production from Euglena gracilis during Dark, Anaerobic Conditions

et al. 2016

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Euglena gracilis is a eukaryotic, unicellular phytoflagellate that has been widely studied in basic science and applied science. Under dark, anaerobic conditions, the cells of E. gracilis produce a wax ester that can be converted into biofuel. Here, we demonstrate that under dark, anaerobic conditions, E. gracilis excretes organic acids, such as succinate and lactate, which are bulk chemicals used in the production of bioplastics. The levels of succinate were altered by changes in the medium and temperature during dark, anaerobic incubation. Succinate production was enhanced when cells were incubated in CM medium in the presence of NaHCO3. Excretion of lactate was minimal in the absence of external carbon sources, but lactate was produced in the presence of glucose during dark, anaerobic incubation. E. gracilis predominantly produced L-lactate; however, the percentage of D-lactate increased to 28.4% in CM medium at 30°C. Finally, we used a commercial strain of E. gracilis for succinate production and found that nitrogen-starved cells, incubated under dark, anaerobic conditions, produced 869.6 mg/L succinate over a 3-day incubation period, which was 70-fold higher than the amount produced by nitrogen-replete cells. This is the first study to demonstrate organic acid excretion by E. gracilis cells and to reveal novel aspects of primary carbon metabolism in this organism.

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Section: Discussionmentioning

confidence: 99%

Succinate and Lactate Production from Euglena gracilis during Dark, Anaerobic Conditions

et al. 2016

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“…A metabolome analysis of E. gracilis (Matsuda et al 2011) showed dynamic shifts in metabolic states in response to changes in culture conditions and provides important information on strategies to improve wax ester fermentation by genetic engineering. To that end, further optimization of genetic tools, such as expression vectors, strong promoters and transformation methods, for E. gracilis are required.…”

Section: Genetic Engineering Of the Metabolic Pathways From Paramylonmentioning

confidence: 99%

Wax Ester Fermentation and Its Application for Biofuel Production

Inui

Ishikawa

Tamoi

2017

Advances in Experimental Medicine and Biology

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In Euglena cells under anaerobic conditions, paramylon, the storage polysaccharide, is promptly degraded and converted to wax esters. The wax esters synthesized are composed of saturated fatty acids and alcohols with chain lengths of 10-18, and the major constituents are myristic acid and myristyl alcohol. Since the anaerobic cells gain ATP through the conversion of paramylon to wax esters, the phenomenon is named "wax ester fermentation". The wax ester fermentation is quite unique in that the end products, i.e. wax esters, have relatively high molecular weights, are insoluble in water, and accumulate in the cells, in contrast to the common fermentation end products such as lactic acid and ethanol.A unique metabolic pathway involved in the wax ester fermentation is the mitochondrial fatty acid synthetic system. In this system, fatty acid are synthesized by the reversal of β-oxidation with an exception that trans-2-enoyl-CoA reductase functions instead of acyl-CoA dehydrogenase. Therefore, acetyl-CoA is directly used as a C donor in this fatty acid synthesis, and the conversion of acetyl-CoA to malonyl-CoA, which requires ATP, is not necessary. Consequently, the mitochondrial fatty acid synthetic system makes possible the net gain of ATP through the synthesis of wax esters from paramylon. In addition, acetyl-CoA is provided in the anaerobic cells from pyruvate by the action of a unique enzyme, oxygen sensitive pyruvate:NADP oxidoreductase, instead of the common pyruvate dehydrogenase multienzyme complex.Wax esters produced by anaerobic Euglena are promising biofuels because myristic acid (C) in contrast to other algal produced fatty acids, such as palmitic acid (C) and stearic acid (C), has a low freezing point making it suitable as a drop-in jet fuel. To improve wax ester production, the molecular mechanisms by which wax ester fermentation is regulated in response to aerobic and anaerobic conditions have been gradually elucidated by identifying individual genes related to the wax ester fermentation metabolic pathway and by comprehensive gene/protein expression analysis. In addition, expression of the cyanobacterial Calvin cycle fructose-1,6-bisphosphatase/sedohepturose-1,7-bisphosphatase, in Euglena provided photosynthesis resulting in increased paramylon accumulation enhancing wax ester production. This chapter will discuss the biochemistry of the wax ester fermentation, recent advances in our understanding of the regulation of the wax ester fermentation and genetic engineering approaches to increase production of wax esters for biofuels.

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“…The storage carbohydrate paramylum is accumulated either photosynthetically or heterotrophically under aerobic conditions up to as much as 90% of dry cell weight (Barsanti et al, 2001). Wax esters are accumulated up to 62% of total lipid content under anaerobic growth conditions (Buetow, 1989;Matsuda et al, 2011;Schneider and Betz, 1985;Teerawanichpan and Qiu, 2010;Tucci et al, 2010) (Fig. 3).…”

Section: The Euglena Storage Molecules -Wax Esters (We) and Paramylonmentioning

confidence: 99%

“…3). The transfer of cells from aerobic to anaerobic growth conditions results in the conversion of paramylum to WE, while, the transfer from anaerobic to aerobic conditions results in the conversion of WE to paramylum (Coleman et al, 1988;Inui et al, 1982;Matsuda et al, 2011;Schneider and Betz, 1985). The shift of Euglena from aerobic to anaerobic conditions induces the malonylCoA independent WE synthesis and the breakdown of the reserve polysaccharide paramylon to provide the acetyl-CoA needed for WE synthesis (Coleman et al, 1988;Inui et al, 1982;Schneider and Betz, 1985).…”

Section: The Euglena Storage Molecules -Wax Esters (We) and Paramylonmentioning

confidence: 99%

Euglenoid flagellates: A multifaceted biotechnology platform

Krajčovič

Vesteg

Schwartzbach

2015

Journal of Biotechnology

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Comparative Profiling Analysis of Central Metabolites inEuglena gracilisunder Various Cultivation Conditions

Cited by 42 publications

References 18 publications

Succinate and Lactate Production from Euglena gracilis during Dark, Anaerobic Conditions

Succinate and Lactate Production from Euglena gracilis during Dark, Anaerobic Conditions

Wax Ester Fermentation and Its Application for Biofuel Production

Euglenoid flagellates: A multifaceted biotechnology platform

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