Lactic acid fermentation of lignocellulose-derived substrates with (hemi)cellulolytic microbes

Due to finiteness of oil resources we are faced with the challenge to produce fuels and chemicals from renewable resources. Lactic acid has great potential as a precursor of bioplastics that can be used as alternatives to conventional plastics. To prevent competition with the human food chain, it is important to produce lactic acid from non-food substrates instead of the food sugars used today. Anticipated Simultaneous Saccharification and Fermentation (SSF) processes are based on the enzymatic breakdown of (ligno)cellulose material to monomeric sugars, which are immediately fermented into chemicals. As added commercial enzymes are a significant cost factor, enzyme usage needs to be reduced and/or optimized. An apparent solution seems using a (hemi)cellulolytic lactate production organism (1,2), which would allow the simultaneous use of commercial enzymes. The ultimate goal would be to develop a fermentation that does not require any enzyme additions at all, resulting in the Consolidated Bio-Processing concept. Unfortunately, such production strains are not available yet. Therefore, we have enriched and isolated (hemi)cellulolytic bacterial strains from environmental samples as candidates for economically feasible lactic acid production. The most promising candidates have been selected and are subject to further development to optimize their potential in enzymatic hydrolysis.

References:

[1] Zhang, X.Z., Sathitsuksanoh, N., Zhu, Z., Zhang, Y.-H.P., Metab. Eng. 13, 364-372. 2011

[2] Yang, S.J., Kataeva, I., Hamilton-Brehm, S.D., Engle, N.L., Tschaplinski, T.J., Doeppke, C., Davis, M.,   Westpheling, J., Adams, M.W.W., Appl. Environ. Microbiol. 75, 4762-4769. 2009