초록
Developing alternative applications for wastes stemming from the processing of industrially applicable crops adds value to industrial crops and limits agricultural land use. Kazak dandelion (Taraxacum kok-saghyz; TKS) and Chicory are rich in inulin. In this study, unhydrolyzed inulin-rich chicory and TKS extracts were assessed as substrates for acetone-butanol-ethanol (ABE) production, using different solventogenic Clostridium species/strains. Extracts from chicory and TKS were rich in inulin (~42 and 36g/L respectively). In addition to inulin, the chicory extract also contained glucose (3.5g/L), sucrose (6.2g/L), fructose (19.5g/L), and kestose (6.0g/L), while the TKS extract contained fructose (28.3g/L), kestose (2.7g/L) and an unidentified sugar (2.0g/L). Among the species/strains tested, Clostridium saccharobutylicum P262 demonstrated superior ability to utilize inulin, with at least 86% and 153% higher cell growth and ABE concentration, respectively, on inulin relative to the other species/strains. With pure commercial inulin, TKS and chicory extracts, C. saccharobutylicum P262 utilized 29.0, 25.2 and 40.5g/L total sugars respectively, and produced 9.7, 8.5 and 12.5g/L ABE, respectively. However, when fructose, the major product of inulin hydrolysis was used as the sole substrate, cell growth and ABE production by C. saccharobutylicum P262 were at least 74% and 83% lower, respectively, relative to the other species tested. These results demonstrate the suitability of C. saccharobutylicum P262 for butanol production from unhydrolyzed plant inulin and also identify limited fructose utilization as a potential metabolic engineering target for improving the fermentability of unhydrolyzed inulin-rich plant extracts to butanol.