| Improved homo L: -lactic acid fermentation from xylose by abolishment of the phosphoketolase pathway and enhancement of the pentose phosphate pathway in genetically modified xylose-assimilating Lactococcus lactis. | |
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MedLine Citation:
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PMID: 21637940 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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In order to achieve efficient homo L-lactic acid fermentation from xylose, we first carried out addition of xylose assimilation ability to Lactococcus lactis IL 1403 by introducing a plasmid carrying the xylRAB genes from L. lactis IO-1 (pXylRAB). Then modification of xylose assimilation pathway was carried out. L. lactis has two pathways for xylose assimilation called the phosphoketolase pathway (PK pathway) that produces both lactic acid and acetic acid and the pentose phosphate pathway (PP pathway) that produces only lactic acid as a final product. Thus a mutant strain that disrupted its phosphokeolase gene (ptk) was constructed. The Δptk mutant harboring pXylRAB lacked the PK pathway and produced predominantly lactic acid from xylose via the PP pathway, although its fermentation rate slightly decreased. Further introduction of the transketolase gene (tkt) to disrupted ptk locus led restoration of fermentation rate and this was attributed to enhancement of the PP pathway. As a result, ptk::tkt strain harboring pXylRAB produced 50.1 g/l of L-lactic acid from xylose with a high optical purity of 99.6% and a high yield of 1.58 (moles per mole xylose consumed) that is close to theoretical value of 1.67 from xylose. |
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Authors:
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Satoru Shinkawa; Kenji Okano; Shogo Yoshida; Tsutomu Tanaka; Chiaki Ogino; Hideki Fukuda; Akihiko Kondo |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-6-3 |
Journal Detail:
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Title: Applied microbiology and biotechnology Volume: - ISSN: 1432-0614 ISO Abbreviation: - Publication Date: 2011 Jun |
Date Detail:
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Created Date: 2011-6-3 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8406612 Medline TA: Appl Microbiol Biotechnol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, 657-8501, Japan. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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