Challenge | Suggested solution |
---|---|
High substrate cost | Lignocellulosic substrates [3, 12,13,14,15, 18, 23, 29, 31,32,33,34,35] Starch based waste [12, 29, 33] Crude glycerol [12, 23, 24, 31] Protein waste [23] Economical feedstock processing methods [3, 18, 29] Inulin [31] |
Low butanol selectivity | Metabolic engineering for disruption of the pathway for acetone [3, 13,14,15, 23, 25, 27, 32, 34] Homo-butanol fermentation via chemical mutagenesis and metabolic engineering [23, 24, 33, 35] Conversion of acetone into isopropanol [13, 15, 23] Decoupling sporulation from solventogenesis [3, 13, 14, 23, 25, 27, 28, 34, 35] |
Low butanol titer | Metabolic engineering and mutagenesis for higher butanol tolerance [13,14,15, 21, 23,24,25, 27, 28, 32,33,34,35] In situ product removal [3, 12,13,14,15, 18, 22, 23, 27, 28, 32, 34, 35] Introducing butanol pathways in other hosts [3, 13, 15, 21, 23,24,25, 27, 33,34,35] Re-enforcing hot channel for butanol formation [14] |
Low butanol yield | Simultaneous utilization of mixed sugars in the hydrolysate without Carbon Catabolite Repression [14, 23, 31] |
Low butanol productivity | Simultaneous utilization of mixed sugars without Carbon Catabolite Repression [3, 23, 28, 29] Fed-batch fermentation [3, 12, 14, 18, 34] Chemostat/continuous culturing [3, 12,13,14,15, 18, 32, 34] Immobilized cell chemostat [3, 12,13,14,15, 18, 34] |
Low O2 tolerance | Co-culturing to maintain anaerobic conditions [32] |
Culture degeneration | Prevention of excessive acidification of the culture [35] |
Phage contamination | Good factory hygiene, strains immune to specific phages [27, 35] |