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Metabolic networks and bioenergetics of Aurantiochytrium sp. B-072 during storage lipid formation
Chaisawang, Montri; Verduyn, Cornelis; Chauvatcharin, Somchai; Suphantharika, Manop.
Afiliação
  • Chaisawang, Montri; Mahidol University. Faculty of Science. Department of Biotechnology. TH
  • Verduyn, Cornelis; Mahidol University. Faculty of Science. Department of Biotechnology. TH
  • Chauvatcharin, Somchai; Mahidol University. Faculty of Science. Department of Biotechnology. TH
  • Suphantharika, Manop; Mahidol University. Faculty of Science. Department of Biotechnology. TH
Braz. j. microbiol ; 43(3): 1192-1205, July-Sept. 2012. ilus, graf, tab
Artigo em Inglês | LILACS | ID: lil-656690
Biblioteca responsável: BR32.1
ABSTRACT
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.
Assuntos


Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: LILACS Assunto principal: Ácidos Docosa-Hexaenoicos / Biomassa / Oxidação / Ácidos Graxos / Eucariotos / Glucose / Lipídeos Idioma: Inglês Revista: Braz. j. microbiol Assunto da revista: Microbiologia Ano de publicação: 2012 Tipo de documento: Artigo País de afiliação: Tailândia Instituição/País de afiliação: Mahidol University/TH

Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: LILACS Assunto principal: Ácidos Docosa-Hexaenoicos / Biomassa / Oxidação / Ácidos Graxos / Eucariotos / Glucose / Lipídeos Idioma: Inglês Revista: Braz. j. microbiol Assunto da revista: Microbiologia Ano de publicação: 2012 Tipo de documento: Artigo País de afiliação: Tailândia Instituição/País de afiliação: Mahidol University/TH
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