Challenges | Influences | Possible solutions |
---|---|---|
High feedstock cost | Substrates are expensive and compete with nutrition (food versus fuel debate) | (i) Construction of novel host or introduction of novel metabolic pathway to utilize cheaper substrates and even carbon dioxide (ii) Development of physical/chemical pretreatment processes that do not require expensive enzymatic treatment |
Low production, yield, and productivity of butanol | Increasing feedstock costs, recovery costs, water usage, energy-intensive process, and the cost of effluent treatment | (i) Develop strains with improved solvent production and/or develop methods for in situ product removal to alleviate product inhibition (ii) Develop continuous fermentation processes to increase volumetric productivity (iii) Develop low-energy methods for solvent recovery and purification |
Poor genetic engineering tools | Metabolic engineering was inhibited by the low frequencies of transformation and recombination | (i) Develop more plasmid vectors and more efficient transformation methods (ii) Develop more efficient gene knockout methods |
Poor understanding of physiology | Lack of knowledge of the entire genome and specific genes in the metabolic pathway that could further improve cellular performance | (i) Gain a detailed characterization and understanding of acidogenic and solventogenic phases and phase transition (ii) Systematically develop an understanding of the complex regulatory circuits and their interactions with metabolism |
Bacteriophage contamination | (1) Decreasing fermentation rate, (2) change in bacterial cell population and morphology, (3) high levels of unutilized sugars | Check through chemical treatment methods, such as: (i) addition of chelating agents to remove divalent cations essential for phage infection, and (ii) use of non-ionic detergents and antibiotics |