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The initial metabolic conversion of levulinic acid in Cupriavidus necator

Paper ID Volume ID Publish Year Pages File Format Full-Text
24063 43493 2011 6 PDF Available
Title
The initial metabolic conversion of levulinic acid in Cupriavidus necator
Abstract

Levulinic acid or 4-ketovaleric acid is a potential renewable substrate for production of polyhydroxyalkanoates. In this work, the initial reactions of LA metabolism by Cupriavidus necator were examined in vitro. The organic acid was converted by membrane-bound crude enzymes obtained from the cells pre-grown on LA, while no LA activity was detected from cells pre-grown on acetic acid. Acetyl-CoA and propionyl-CoA were two major intermediates in the initial reactions of LA conversion. A mass balance on propionyl-CoA accounts for 84 mol% of LA added in vitro. It explains an interesting phenomenon that 3-hydroxbutyrate and 3-hydroxyvalerate are two major monomers of the biopolyester formed from LA, instead of 4-hydroxvalerate that has the similar chemical structure of LA as the precursor. A Monod model was used to describe the kinetics of LA utilization as a sole carbon source or a co-substrate of glucose and fructose. The μmax and Km of LA alone were 0.26 h−1 and 0.01 g/L, respectively. The content and composition of PHA are also dependent on the culture conditions such as carbon to nitrogen ratio. The in vitro observation is supported by the high utilization rate of LA and the high molar percentage of 3HB and 3HV in the PHA derived from LA.

► We determine the initial intermediates of levulinic acid in Cupriavidus necator. ► LA is converted to acetyl-CoA and propionyl-CoA by in vitro bioconversion. ► The LA acyl-CoA synthetase is an inducible, membrane-bound enzyme. ► The LA utilization rate is similar to other CoA-binding organic acids. ► The PHA composition from LA can be altered by controlling the carbon nitrogen ratio.

Keywords
μ, specific growth rate (h−1); μmax, maximum specific growth rate (h−1); 3HB, 3-hydroxybutyrate; 3HV, 3-hydroxyvalerate; 4HV, 4-hydroxyvalerate; AcCoA, acetyl-CoA; ATP, adenosine tri-phosphate; C/N, carbon to nitrogen; CoA, coenzyme A; Km, substrate satur
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The initial metabolic conversion of levulinic acid in Cupriavidus necator
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 155, Issue 3, 20 September 2011, Pages 293–298
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us