Biomass hydrolysates

Production of Ethanol from Cellulosic Biomass Hydrolysates Using Genetically Engineered Saccharomyces Yeast Capable of Cofermenting Glucose and Xylose... 

The use of recombinant microorganisms for cofermentation is one of the most promising approaches in the field of bioethanol production, though their use for large-scale industrial processes still requires fine-tuning of the reliability of the entire process (2). The technical hurdles of cofermentation increase when real biomass hydrolysates have to be fermented. In fact, whatever the biomass pretreatment, the formation of degradation byproducts that could inhibit the fermentation usually requires the addition of a further detoxification step. Therefore, the production of ethanol from hydrolysates should be considered in its entirety, from the optimal pretreatment to the choice of the proper fermentation process. 

Sedlak, M. and Ho,N.W.Y. (2004). Production of Ethanol From Cellulosic Biomass Hydrolysates Using Genetically Engineered Saccharomyces Yeast Capable of Cofermenting Glucose and Xylose. Appl. Biochem. Biotechnol., 113-116, 403-416. 

Helle, S., Cameron, D., et al., Effect of inhibitory compounds found in biomass hydrolysates on growth and xylose fermentation by a genetically engineered strain of Saccharomyces cerevisiae. Enzyme Microbial Technology 2003, 33 (6), 786-792. 

The stable strain 1400 (LNH-ST) was confirmed to be able to effectively coferment glucose and xylose by a continuous process in a 9000-L pilot scale fermentor with both pure sugars and sugars from crude corn biomass hydrolysates as the feedstocks [25]. 

Fig. 3. a Determination of positional enrichment (24%) in the methyl groups of C-la-belled valine purified fron a biomass hydrolysate of C. glutamicum by integration of the satellites in the NMR spectrum (b) measurement of relative isotopomer abundancies from singlet, doublet (2 varieties) and doublet-of-doublets signals in the NMR spectrum of C-labelled alanine... 

Simultaneous substrate utilization is the prerequisite for single-cell biorefinery. The selected microbes must possess the possibility to utilize the multiple compounds in the substrate mixture or biomass hydrolysates. However, to design a single-cell biorefinery system, the coproduction in single cell is necessary. 

Wickramasinghe SR, Grzenia DL (2008) Adsorptive membranes and resins for acetic acid removal from biomass hydrolysates. Desalination 234(1-3) 144-151. doi 10.1016/j.desal. 2007.09.080... 

Even though the productivities of isobutene fermentation are too low for commercial application, further research and optimisation can help these processes realise their potential. Also, isobutene-producing strains cannot yet utilise cheap substrates like lignocellulosic biomass hydrolysates. Further strain development will probably give a solution. 

Pienkos P, Zhang M (2009) Role of pretreatment and conditioning processes oti toxicity of lignocellulosic biomass hydrolysates. Cellulose 16(4) 743-762 Poblete-Castro I et al (2012) Industrial biotechnology of Pseudomormsputida and related species. Appl Microbiol Biotechnol 93(6) 2279-90... 

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