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Butanol production from inulin-rich chicory and Taraxacum kok-saghyz extracts: Determination of sugar utilization profile of Clostridium saccharobutylicum P262

Ujor, Victor, Bharathidasan, Ashok K., Michel, Frederick C., Ezeji, Thaddeus C., Cornish, Katrina
Industrial crops and products 2015 v.76 pp. 739-748
Clostridium, Taraxacum kok-saghyz, agricultural land, butanol, cell growth, chicory, fructose, glucose, hydrolysis, industrial crops, inulin, kestose, land use, metabolic engineering, plant extracts, sucrose, wastes
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.