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Improvement on the yield of polyhydroxyalkanotes production from cheese whey by a recombinant Escherichia coli strain using the proton suicide methodology

Paper ID Volume ID Publish Year Pages File Format Full-Text
17243 42653 2014 8 PDF Available
Title
Improvement on the yield of polyhydroxyalkanotes production from cheese whey by a recombinant Escherichia coli strain using the proton suicide methodology
Abstract

•The proton suicide method was used to generate E. coli mutant strains.•E. coli mutant strains had reduced organic acids production capacity.•Strain P8-X8 was selected for its high PHA accumulation capacity.•Bioreactor cultivations using cheese whey as substrate were conducted.•Low organic acids production was obtained and PHA yield on lactose was improved.

In this work Escherichia coli strain CML3-1 was engineered through the insertion of Cupriavidus necator P(3HB)-synthesis genes, fused to a lactose-inducible promoter, into the chromosome, via transposition-mediated mechanism. It was shown that polyhydroxyalkanotes (PHAs) production by this strain, using cheese whey, was low due to a significant organic acids (OA) synthesis. The proton suicide method was used as a strategy to obtain an E. coli mutant strain with a reduced OA-producing capacity, aiming at driving bacterial metabolism toward PHAs synthesis.Thirteen E. coli mutant strains were obtained and tested in shake flask assays, using either rich or defined media supplemented with lactose. P8-X8 was selected as the best candidate strain for bioreactor fed-batch tests using cheese whey as the sole carbon source. Although cell growth was considerably slower for this mutant strain, a lower yield of OA on substrate (0.04 CmolOA/Cmollac) and a higher P(3HB) production (18.88 gP(3HB)/L) were achieved, comparing to the original recombinant strain (0.11 CmolOA/Cmollac and 7.8 gP(3HB)/L, respectively). This methodology showed to be effective on the reduction of OA yield by consequently improving the P(3HB) yield on lactose (0.28 CmolP(3HB)/Cmollac vs 0.10 CmolP(3HB)/Cmollac of the original strain).

Keywords
CFU, colony forming units; CW, cheese whey; DCW, dry cell weight; LB, Luria Bertani; OA, organic acids; PHA, polyhydroxyalkanoates; P(3HB), polyhydroxybutyrate; qlac, specific lactose consumption rate; rP(3HB), P(3HB) volumetric production rate; rOA, OA v
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Improvement on the yield of polyhydroxyalkanotes production from cheese whey by a recombinant Escherichia coli strain using the proton suicide methodology
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 55, 5 February 2014, Pages 151–158
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