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Integrative transformation system for the metabolic engineering of the sphingoid base-producing yeast Pichia ciferrii.

ABSTRACT: We have developed an integrative transformation system for metabolic engineering of the tetraacetyl phytosphingosine (TAPS)-secreting yeast Pichia ciferrii. The system uses (i) a mutagenized ribosomal protein L41 gene of P. ciferrii as a dominant selection marker that confer resistance to the antibiotic cycloheximide and (ii) a ribosomal DNA (rDNA) fragment of P. ciferrii as a target for multicopy gene integration into the chromosome. A locus within the nontranscribed region located between 5S and 26S rDNAs was selected as the integration site. A maximum frequency of integrative transformation of approximately 1,350 transformants/ microg of DNA was observed. To improve the de novo synthesis of sphingolipid, the LCB2 gene, encoding a subunit of serine palmitoyltransferase, which catalyzes the first committed step of sphingolipid synthesis, was cloned from P. ciferrii and overexpressed under the control of the P. ciferrii glyceraldehyde-3-phosphate dehydrogenase promoter. After transformation of an LCB2 gene expression cassette, several transformants that contained approximately five to seven copies of transforming DNA in the chromosome and exhibited about 50-fold increase in LCB2 mRNA relative to the wild type were identified. These transformants were observed to produce approximately two times more TAPS than the wild type.

SUBMITTER: Bae JH

PROVIDER: S-EPMC143681 | biostudies-literature | 2003 Feb

REPOSITORIES: biostudies-literature

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Integrative transformation system for the metabolic engineering of the sphingoid base-producing yeast Pichia ciferrii.

Bae Jung-Hoon JH Sohn Jung-Hoon JH Park Chang-Seo CS Rhee Joon-Shick JS Choi Eui-Sung ES

Applied and environmental microbiology 20030201 2

We have developed an integrative transformation system for metabolic engineering of the tetraacetyl phytosphingosine (TAPS)-secreting yeast Pichia ciferrii. The system uses (i) a mutagenized ribosomal protein L41 gene of P. ciferrii as a dominant selection marker that confer resistance to the antibiotic cycloheximide and (ii) a ribosomal DNA (rDNA) fragment of P. ciferrii as a target for multicopy gene integration into the chromosome. A locus within the nontranscribed region located between 5S a ...[more]

PMID: 12570999

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Project description:Itaconic acid (IA), or 2-methylenesuccinic acid, has a broad spectrum of applications in the biopolymer industry owing to the presence of one vinyl bond and two acid groups in the structure. Its polymerization can follow a similar mechanism as acrylic acid but additional functionality can be incorporated into the extra beta acid group. Currently, the bio-based production of IA in industry relies on the fermentation of the filamentous fungus Aspergillus terreus. However, the difficulties associated with the fermentation undertaken by filamentous fungi together with the pathogenic potential of A. terreus pose a serious challenge for industrial-scale production. In recent years, there has been increasing interest in developing alternative production hosts for fermentation processes that are more homogenous in the production of organic acids. Pichia kudriavzevii is a non-conventional yeast with high acid tolerance to organic acids at low pH, which is a highly desirable trait by easing downstream processing. We introduced cis-aconitic acid decarboxylase gene (cad) from A. terreus (designated At_cad) into this yeast and established the initial titer of IA at 135 ± 5 mg/L. Subsequent overexpression of a native mitochondrial tricarboxylate transporter (herein designated Pk_mttA) presumably delivered cis-aconitate efficiently to the cytosol and doubled the IA production. By introducing the newly invented CRISPR-Cas9 system into P. kudriavzevii, we successfully knocked out both copies of the gene encoding isocitrate dehydrogenase (ICD), aiming to increase the availability of cis-aconitate. The resulting P. kudriavzevii strain, devoid of ICD and overexpressing Pk_mttA and At_cad on its genome produced IA at 505 ± 17.7 mg/L in shake flasks, and 1232 ± 64 mg/L in fed-batch fermentation. Because the usage of an acid-tolerant species does not require pH adjustment during fermentation, this work demonstrates the great potential of engineering P. kudriavzevii as an industrial chassis for the production of organic acid.

Dataset Information

Integrative transformation system for the metabolic engineering of the sphingoid base-producing yeast Pichia ciferrii.

Publications

Integrative transformation system for the metabolic engineering of the sphingoid base-producing yeast Pichia ciferrii.

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