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Engineering the acetyl‐CoA transportation system of candida tropicalis enhances the production of dicarboxylic acid
Author(s) -
Cao Zhuan,
Gao Hong,
Liu Ming,
Jiao Peng
Publication year - 2006
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.200500008
Subject(s) - candida tropicalis , metabolic engineering , acetyl coa , biochemistry , flux (metallurgy) , metabolic pathway , beta oxidation , mitochondrion , metabolic flux analysis , citric acid cycle , yield (engineering) , chemistry , metabolism , biology , enzyme , yeast , organic chemistry , materials science , metallurgy
Abstract Dicarboxylic acids (DCAs) can be obtained by oxidizing alkanes by Candida tropicalis. Through α‐monocarboxylic acids (MCAs), α‐ and ω‐oxidation yield α‐ or ω‐DCAs, respectively. However, both MCAs and DCAs may be degraded to acetyl‐CoA by β‐oxidation, resulting in a limited DCA yield. Acetyl‐CoA can be transported into the mitochondrion for the TCA cycle by carnitine acetyltransferase (CAT), by which the energy generation and β‐oxidation are connected. In this paper, we present a method to reconstruct the metabolic pathway by inhibiting the acetyl‐CoA transportation system. Metabolic engineering is applied on the acetyl‐CoA transportation system, but not the key enzymes in β‐oxidation. Starting with the original strain W10‐1, cat heterozygote CZ‐15 and cat homozygote CKC‐11 were obtained by gene knockout. The CAT specific activity in CZ‐15 was about 50% lower than that in W10‐1, resulting in a 21.0% increase of the DCA concentration, and a 12% increase of the molar conversion of alkane, reaching 61.6%. However, no CAT activity was detected in CKC‐11, and CKC‐11 could not grow on alkane. These results indicate that inhibition of β‐oxidation via reconstruction of the transportation process between organelles can facilitate DCA production, but that totally blocking the &&bgr;gr;‐oxidation would be harmful for energy supply. We thus provide a novel insight into regulation of the β‐oxidation system and metabolic flux. Further understanding of β‐oxidation and the acetyl‐CoA transportation system in Candida tropicalis is reached through examination of fermentation data by metabolic flux analysis.