| Evolution of D-lactate dehydrogenase activity from glycerol dehydrogenase and its utility for D-lactate production from lignocellulose. | |
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MedLine Citation:
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PMID: 22065761 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Lactic acid, an attractive, renewable chemical for production of biobased plastics (polylactic acid, PLA), is currently commercially produced from food-based sources of sugar. Pure optical isomers of lactate needed for PLA are typically produced by microbial fermentation of sugars at temperatures below 40 °C. Bacillus coagulans produces L(+)-lactate as a primary fermentation product and grows optimally at 50 °C and pH 5, conditions that are optimal for activity of commercial fungal cellulases. This strain was engineered to produce D(-)-lactate by deleting the native ldh (L-lactate dehydrogenase) and alsS (acetolactate synthase) genes to impede anaerobic growth, followed by growth-based selection to isolate suppressor mutants that restored growth. One of these, strain QZ19, produced about 90 g L(-1) of optically pure D(-)-lactic acid from glucose in < 48 h. The new source of D-lactate dehydrogenase (D-LDH) activity was identified as a mutated form of glycerol dehydrogenase (GlyDH; D121N and F245S) that was produced at high levels as a result of a third mutation (insertion sequence). Although the native GlyDH had no detectable activity with pyruvate, the mutated GlyDH had a D-LDH specific activity of 0.8 μmoles min(-1) (mg protein)(-1). By using QZ19 for simultaneous saccharification and fermentation of cellulose to D-lactate (50 °C and pH 5.0), the cellulase usage could be reduced to 1/3 that required for equivalent fermentations by mesophilic lactic acid bacteria. Together, the native B. coagulans and the QZ19 derivative can be used to produce either L(+) or D(-) optical isomers of lactic acid (respectively) at high titers and yields from nonfood carbohydrates. |
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Authors:
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Qingzhao Wang; Lonnie O Ingram; K T Shanmugam |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. Date: 2011-11-07 |
Journal Detail:
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Title: Proceedings of the National Academy of Sciences of the United States of America Volume: 108 ISSN: 1091-6490 ISO Abbreviation: Proc. Natl. Acad. Sci. U.S.A. Publication Date: 2011 Nov |
Date Detail:
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Created Date: 2011-11-23 Completed Date: 2012-01-27 Revised Date: 2012-05-22 |
Medline Journal Info:
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Nlm Unique ID: 7505876 Medline TA: Proc Natl Acad Sci U S A Country: United States |
Other Details:
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Languages: eng Pagination: 18920-5 Citation Subset: IM |
Affiliation:
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Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA. |
| Data Bank Information | |
Bank Name/Acc. No.:
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GENBANK/HQ699676; HQ699677; HQ699678 |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Amino Acid Sequence Bacillus / genetics*, metabolism Base Sequence Chromatography, High Pressure Liquid Evolution, Molecular* Genetic Engineering / methods Hydrogen-Ion Concentration Lactate Dehydrogenases / genetics*, metabolism Lactic Acid / biosynthesis* Lignin / chemistry* Models, Molecular* Molecular Sequence Data Mutagenesis Mutation / genetics Reverse Transcriptase Polymerase Chain Reaction Sequence Analysis, DNA Sugar Alcohol Dehydrogenases / biosynthesis, genetics* Temperature Transformation, Bacterial / genetics |
| Chemical | |
Reg. No./Substance:
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11132-73-3/lignocellulose; 50-21-5/Lactic Acid; 9005-53-2/Lignin; EC 1.1.-/Lactate Dehydrogenases; EC 1.1.-/Sugar Alcohol Dehydrogenases; EC 1.1.1.28/D-lactate dehydrogenase; EC 1.1.1.6/glycerol dehydrogenase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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