title: Citric acid production from sucrose using a recombinant strain of the yeast Yarrowia lipolytica.
abstract: The yeast Yarrowia lipolytica is able to secrete high amounts of several organic acids under conditions of growth limitation and carbon source excess. Here we report the production of citric acid (CA) in a fed-batch cultivation process on sucrose using the recombinant Y. lipolytica strain H222-S4(p67ICL1) T5, harbouring the invertase encoding ScSUC2 gene of Saccharomyces cerevisiae under the inducible XPR2 promoter control and multiple ICL1 copies (10-15). The pH-dependent expression of invertase was low at pH 5.0 and was identified as limiting factor of the CA-production bioprocess. The invertase expression was sufficiently enhanced at pH 6.0-6.8 and resulted in production of 127-140 g l(-1) CA with a yield Y (CA) of 0.75-0.82 g g(-1), whereas at pH 5.0, 87 g l (-1) with a yield Y (CA) of 0.51 g g(-1) were produced. The CA-productivity Q (CA) increased from 0.40 g l (-1) h(-1) at pH 5.0 up to 0.73 g l (-1) h(-1) at pH 6.8. Accumulation of glucose and fructose at high invertase expression level at pH 6.8 indicated a limitation of CA production by sugar uptake. The strain H222-S4(p67ICL1) T5 also exhibited a gene-dose-dependent high isocitrate lyase expression resulting in strong reduction (<5%) of isocitric acid, a by-product during CA production.
authors: Institut für Mikrobiologie, Technische Universität Dresden, 01062 Dresden, Germany.
authors: André
authors: A
authors: Förster
authors: Andreas
authors: A
authors: Aurich
authors: Stephan
authors: S
authors: Mauersberger
authors: Gerold
authors: G
authors: Barth
mesh_terms: D019343:Citric Acid / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics; D007522:Isocitrate Lyase / Q000235:genetics; D030781:Organisms, Genetically Modified; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D013395:Sucrose / Q000378:metabolism*; D025062:Yarrowia / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D043324:beta-Fructofuranosidase / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D019343:Citric Acid; D013395:Sucrose; C468437:SUC2 protein, S cerevisiae; D043324:beta-Fructofuranosidase; C542285:ICL1 protein, S cerevisiae; D007522:Isocitrate Lyase