Kinetic characterization and structure analysis of an altered polyol dehydrogenase with d;#8208;lact
Explore the source record for details and available documents.
Chauliac, Diane↗
Engineering topics
Chauliac, Diane
Publications and source records attributed to Chauliac, Diane.
A Combined Thermochemical and Microbial Process for Recycling Polylactic Acid Polymer to Optically Pure L-Lactic Acid for Reuse
Polylactic acid polymer (PLA) produced from renewable resources can be recycled at the end of life to constituent monomer, optically pure lactic acid (LA), by a combination of chemical and biological processes. Efficient application of this closed loop of LA-PLA plastics-LA can minimize accumulation of plastics waste that pollute land and oceans. Temperature-dependent hydrolysis of PLA in water to LA follows apparent first order decay kinetics after a short lag. A modified Gompertz equation can explain the overall hydrolysis process. Alkali increased the rate of hydrolysis of PLA and reduced the length of lag period compared to water alone. The stoichiometry of base added to LA released was 1.0. The highest lactic acid yield was 0.95 g g -1 of PLA. D-LA in the syrup obtained after hydrolysis of PLA-plastics was removed using an engineered Escherichia coli to produce a L-LA syrup with an optical purity ≥ 99%. Here, these results show that thermochemical hydrolysis of PLA-based plastics to LA with optimum amount of base followed by bio-based purification to L-LA is an effective method of recycling PLA-plastics for reuse.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Metabolic engineering of Escherichia coli for the production of butyric acid at high titer and productivity
Background: Several anaerobic bacteria produce butyric acid, a commodity chemical with use in chemical, pharmaceutical, food and feed industries, using complex media with acetate as a co-product. Butyrate titer of various recombinant Escherichia coli did not exceed 10 g l -1 in batch fermentations in any of the media tested. Results: A recombinant E. coli (strain LW393) that produced butyrate as the major fermentation product was constructed with genes from E. coli, Clostridium acetobutylicum and Treponema denticola. Strain LW393 produced 323±6 mM (28.4±0.4 g l -1 ) butyric acid in batch fermentations in mineral salt medium with glucose as C source at a yield of 0.37±0.01 g (g glucose consumed) -1 . Butyrate accounted for 90% of the total products produced by the culture. Supplementing this medium with yeast extract further increased butyric acid titer to 375±4 mM. Average volumetric productivity of butyrate with xylose as C source was 0.89±0.07 g l -1 h -1 . Conclusions: The butyrate titer reported in this study is about 2.5–3-times higher than the values reported for other recombinant E. coli and this is achieved in mineral salt medium with an expectation of lower purifcation and production cost of butyrate.
09 BIOMASS FUELS↗