Thesis by Rémi Hocq*, 2020 Yves Chauvin prize-winner

A major challenge of the energy transition, the substitution of petrochemical processes by bioprocesses requires the use of catalysts (or microorganisms) to produce molecules for industry, with a lower impact on the environment. One of these microorganisms, Clostridium beijerinckii DSM 6423, is capable of converting a broad variety of sugars into n-butanol and isopropanol — bio-alcohols that can be used directly or dehydrated to produce propylene and butenes — via fermentation. However, its fermentation performances are currently too low, limiting its use on an industrial scale.

This thesis project (figure) focused firstly on fermentation performances in the presence of sugar industry by-products (molasses). This work consisted in stabilizing physiological states in continuous culture conditions, then characterizing them via an in silicoapproach. Thereafter, the combined use of the latest omic analysis toolsb, probing C. beijerinckii DNA, RNA and proteins, generated fundamental data shedding light on its metabolism and establishing a robust and crucial working platform for its ultimate exploitation. Finally, in order to optimize the microorganism’s capacities, a major challenge was overcome with the design of a first genetic modification toolc and its use to characterize the sigma 54 protein, an essential factor for the production of alcohol in this microorganism(1-2).

Hocq VA
Diagram of the approach adopted.

Hence, via the creation and intellectual protection of a first “platform” strain, this same tool has paved the way for the optimization of the fermentation performances of this microorganism of industrial interest.

*Thesis entitled "Clostridium beijerinckii DSM 6423, an emerging platform strain for solvent bioproduction"

a - Using complex computer-based calculations or computer models
b - Molecular scale analyses of DNA (genomic), RNA (transcriptomic) and proteins (proteomic)
c - Based on CRISPR-Cas9 technology

(1) R. Hocq, M. Bouilloux-Lafont, N. Lopes Ferreira, F. Wasels. Sci Rep. 2019 ; 9(1):7228.
DOI: 10.1038/s41598-019-43822-2

(2) M. Diallo, R. Hocq, F. Collasa, G. Chartier, F. Wasels, H. Surya Wijayaa, M.W.T. Werte, E.J.H. Wolberta, S.W.M.Kengen, J. der Oost, N. Lopes Ferreira, A.M. López-Contreras. Methods. 2020 ; 172:51-60.
DOI: 10.1016/j.ymeth.2019.07.022

Scientific contact: francois.wasels@ifpen.fr