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Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation
Baffled shake flask cultivation of Aurantiochytrium sp. B-072 was carried out at in a glucose-monosodium glutamate mineral medium at different C/N-ratios (30–165) with glucose fixed at 90 g/L. With increasing C/N-ratio, a modest increase in lipid content (60 to 73 % w/w) was observed whereas fat-fre...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Sociedade Brasileira de Microbiologia
2012
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768889/ https://www.ncbi.nlm.nih.gov/pubmed/24031944 http://dx.doi.org/10.1590/S1517-838220120003000047 |
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author | Chaisawang, Montri Verduyn, Cornelis Chauvatcharin, Somchai Suphantharika, Manop |
author_facet | Chaisawang, Montri Verduyn, Cornelis Chauvatcharin, Somchai Suphantharika, Manop |
author_sort | Chaisawang, Montri |
collection | PubMed |
description | Baffled shake flask cultivation of Aurantiochytrium sp. B-072 was carried out at in a glucose-monosodium glutamate mineral medium at different C/N-ratios (30–165) with glucose fixed at 90 g/L. With increasing C/N-ratio, a modest increase in lipid content (60 to 73 % w/w) was observed whereas fat-free biomass decreased but overall biomass showed little variation. FA-profiles were not affected to a large extent by C/N-ratio and absolute docosahexaenoic (DHA)-levels fell in narrow range (5–6 g/L). However at C/N > 64 a rapid decrease in lipid synthetic rate and/or incomplete glucose utilization occurred. Glucose and FA-fluxes based on fat-free biomass peaked at a C/N ratio of 56. This condition was chosen for calculation of the redox balance (NAD(P)H) and energy (ATP) requirement and to estimate the in vivo P/O ratio during the main period of fatty acid biosynthesis. Several models with different routes for NADPH, acetyl-CoA formation and re-oxidation of OAA formed via ATP-citrate lyase were considered as these influence the redox- and energy balance. As an example, using a commonly shown scheme whereby NADPH is supplied by a cytosolic “transhydrogenase cycle” (pyruvate-OAA-malate-pyruvate) and OAA formed by ATP-citrate lyase is recycled via import into the mitochondria as malate, the calculated NADPH-requirement amounted to 5.5 with an ATP-demand of 10.5 mmol/(g fat-free biomass x h) and an in vivo P/O-ratio (not including non-growth associated maintenance) of 1.6. The lowest ATP requirement is found when acetyl-CoA would be transported directly from the mitochondria to the cytosol by carnitine acetyltransferase. Assay of some enzymes critical for NADPH supply indicates that activity of glucose-6-phosphate dehydrogenase, the first enzyme in the HMP pathway, is far insufficient for the required NADPH-flux and malic enzyme must be a major source. Activity of the latter (ca. 300 mU/mg protein) far exceeds that in oleaginous fungi and yeast. |
format | Online Article Text |
id | pubmed-3768889 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | Sociedade Brasileira de Microbiologia |
record_format | MEDLINE/PubMed |
spelling | pubmed-37688892013-09-12 Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation Chaisawang, Montri Verduyn, Cornelis Chauvatcharin, Somchai Suphantharika, Manop Braz J Microbiol Microbial Physiology Baffled shake flask cultivation of Aurantiochytrium sp. B-072 was carried out at in a glucose-monosodium glutamate mineral medium at different C/N-ratios (30–165) with glucose fixed at 90 g/L. With increasing C/N-ratio, a modest increase in lipid content (60 to 73 % w/w) was observed whereas fat-free biomass decreased but overall biomass showed little variation. FA-profiles were not affected to a large extent by C/N-ratio and absolute docosahexaenoic (DHA)-levels fell in narrow range (5–6 g/L). However at C/N > 64 a rapid decrease in lipid synthetic rate and/or incomplete glucose utilization occurred. Glucose and FA-fluxes based on fat-free biomass peaked at a C/N ratio of 56. This condition was chosen for calculation of the redox balance (NAD(P)H) and energy (ATP) requirement and to estimate the in vivo P/O ratio during the main period of fatty acid biosynthesis. Several models with different routes for NADPH, acetyl-CoA formation and re-oxidation of OAA formed via ATP-citrate lyase were considered as these influence the redox- and energy balance. As an example, using a commonly shown scheme whereby NADPH is supplied by a cytosolic “transhydrogenase cycle” (pyruvate-OAA-malate-pyruvate) and OAA formed by ATP-citrate lyase is recycled via import into the mitochondria as malate, the calculated NADPH-requirement amounted to 5.5 with an ATP-demand of 10.5 mmol/(g fat-free biomass x h) and an in vivo P/O-ratio (not including non-growth associated maintenance) of 1.6. The lowest ATP requirement is found when acetyl-CoA would be transported directly from the mitochondria to the cytosol by carnitine acetyltransferase. Assay of some enzymes critical for NADPH supply indicates that activity of glucose-6-phosphate dehydrogenase, the first enzyme in the HMP pathway, is far insufficient for the required NADPH-flux and malic enzyme must be a major source. Activity of the latter (ca. 300 mU/mg protein) far exceeds that in oleaginous fungi and yeast. Sociedade Brasileira de Microbiologia 2012 2012-06-01 /pmc/articles/PMC3768889/ /pubmed/24031944 http://dx.doi.org/10.1590/S1517-838220120003000047 Text en © Sociedade Brasileira de Microbiologia http://creativecommons.org/licenses/by-nc/3.0/ All the content of the journal, except where otherwise noted, is licensed under a Creative Commons License |
spellingShingle | Microbial Physiology Chaisawang, Montri Verduyn, Cornelis Chauvatcharin, Somchai Suphantharika, Manop Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation |
title | Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation |
title_full | Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation |
title_fullStr | Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation |
title_full_unstemmed | Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation |
title_short | Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation |
title_sort | metabolic networks and bioenergetics of aurantiochytrium sp. b-072 during storage lipid formation |
topic | Microbial Physiology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768889/ https://www.ncbi.nlm.nih.gov/pubmed/24031944 http://dx.doi.org/10.1590/S1517-838220120003000047 |
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