Metabolic Engineering of Clostridium Pasteurianum

Bioproduction of fuels and chemicals has become a research field of increasing interest, as rising CO₂ levels in the atmosphere and growing awareness of its consequences indicate the need for more sustainable alternatives compared to the petroleum-based industries. Clostridium pasteurianum is a gram-positive, spore-forming anaerobe which is of great industrial interest as it can produce not only high-energy biofuels such as butanol and ethanol but also 1,3-propanediol which is a precursor for the production of various polymers. C. pasteurianum has the ability to utilize glycerol, a waste byproduct from biodiesel and bioethanol production, as a substrate for solvent production [1]. Furthermore, C. pasteurianum has recently been shown to be potentially electroactive [2], which makes it a good candidate for development of electricity-driven bioprocesses.

Whereas metabolic engineering has already been applied to various clostridium stains, efficient genetic tools are still highly demanded for C. pasteurianum. Genetic manipulation of C. pasteurianum is expected to overcome the low productivity of current strains and to further increase its bioindustrial potential. We have developed genetic tools for metabolic engineering of C. pasteurianum in order to create a platform microorganism that can be adapted to different substrates and produce increased amounts of desired products by making use of its electroactivity. To this end E. coli-C. pasteurianum shuttle vectors were created for homologous and heterologous overexpression in C. pasteurianum. Transformation of C. pasteurianum was facilitated by in vivo methylation of foreign DNA to protect shuttle vectors from clostridial restriction endonucleases. Strategies to further increase transformation efficiency and to enable efficient gene knockouts in C. pasteurianum are currently unter development.

References

[1]   W. Sabra, C. Groeger, P.N. Sharma, and A.-P. Zeng (2014) Appl. Microbial and Biotechnol. 98:4267–4276.

[2] O. Choi, T. Kim, H. M. Woo, and Y. Um (2014) Scientific reports, 4.