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Volume 8 Journal of Biotechnology & Biomaterials
ISSN: 2155-952X Biotech Congress 2018 & Enzymology 2018
March 05-07, 2018
JOINT EVENT
20th Global Congress on Biotechnology
3rd International Conference on Enzymology and Molecular Biology
&
March 05-07, 2018 London, UK
Engineering carbon-conserving synthetic pathways for assimilation and conversion of C5/C6 carbon
sources into added value chemicals
Jean M François1,2 , Ceren Alkim1,2 and Thomas Walther1,3
1Université Fédérale Toulouse Midi-Pyrénées, France
2Toulouse White Biotechnology, France
3Technische Universität Dresden, Germany
The development of carbon efficient pathways for added value (bio)chemicals production is the essence of White Biotechnology.
The limit of carbon conservation in all (bio)chemical syntheses is determined by the electron balance in substrate(s) and
product(s). Frequently, natural metabolic networks do not have the stoichiometric capacity to produce a value-added compound
at yields that correspond to the thermodynamic maximum. A good example of natural metabolic networks lacking stoichiometric
efficiency is the bioproduction of glycolic acid (GA), a two carbon compound of considerable industrial interest notably in cosmetics
and biodegradable polymers. We addressed this objective to approach this maximal conversion yield by employing the following
strategies. Firstly, we reconsider a completely different route of C5 assimilation that by-passes the decarboxylation reaction in the
pentose phosphate pathway and that rely on the carbon-conserving aldolytic cleavage of X1P or R1P to yield the C2 compound
glycolaldehyde and the C3 DHAP compound. This metabolic scheme required the expression of human hexo(fructo)kinase(Khk-C)
and human aldolase (Aldo-B). Then glycoaldehyde can be either reduced by endogenous aldehyde reductase to produce ethylene
(EG) glycol or oxidized into glycolic acid. With this approach, we obtained yield of EG and GA close to maximal theoretical yield of 1
mol/ mol sugar. Interestingly, we found that the engineered strain expressing this synthetic pathway exhibited a remarkable rewiring
of the metabolic networks that culminate with a dramatic reduced metabolites and metabolic energy levels. We then combined this
synthetic pathway with the natural glyoxylate shunt that can be engineered to produce GA from DHAP. This combination led to
an optimized production strain that produced ~30 % more GA from a xylose/glucose mixture (66%/33%) than when the natural
pathway is working alone.
Biography
Jean M François got his PhD in Biological Science and Agronomy from the University of Louvain (Belgium) in 1988. He is Professor of Industrial Microbiology and
BioNanotechnology at the Federal University of Toulouse, School of Engineer. His research activity concerns integrated physiology and functional genomics in
microbial systems, with a specific focus on carbon and energy metabolism in yeast and filamentous fungi . He is author of more than 180 papers and 15 patents
and Editor in Chief of BMC Biotechnology for Biofuels.
Jean M François et al., J Biotechnol Biomater 2018, Volume 8
DOI: 10.4172/2155-952X-C2-091