Title:
Understanding Effect of Sugar Composition on Growth Kinetics: Fermentation of Glucose and Xylose by Clostridium Acetobutylicum ATCC 824
Author(s):
Birgen, C., Markussen, S., Preisig, H.A., Wittgens, B., Wentzel, A., Sarkar, U., Saha, S., Baksi, S.
Document(s):
Paper
Slide presentation
Abstract:
Low yield is one of the major challenges for fermentation of biomass-derived sugars, which is a mixture of C5 and C6 sugars; because current methodologies mainly focus on fermentation of C6 sugars while discarding rest of the feedstock. Therefore, our objective is twofold: i) understanding how C5 and C6 sugars are utilized and the interactions between them, and ii) investigating the effect of different sugar compositions on growth kinetics. We chose xylose as a representative C5 sugar and glucose as C6 sugar, and Clostridium acetobutylicum ATCC 824 as the strain. We performed batch growth experiments at anaerobic and static conditions at different ratios of glucose and xylose. All cultures grew successfully. We observed carbon catabolite repression, which led to sequential sugar utilization, therefore diauxic growth. After utilizing glucose completely, the cells could not directly start using xylose, likely because they had not synthesized the required enzymes yet. When the cultures switched from glucose to xylose, there was an intermediate phase characterized by a decay followed by a lag period in which the necessary enzymes presumably were generated, and the next growth phase was initiated. Specific growth rates were 0.14, 0.4, 0.54, 0.68, 0.55 and 0.55 h-1 for cultures grown on 0%, 20%, 40%, 60%, 80% and 100% of glucose with a total sugar concentration of 1 g/L, respectively. The growth on xylose was slower than on glucose, which is in good agreement with sugar consumption rates. Cell mass yield on glucose was higher than on xylose for all the cultures. This work demonstrates the possibility of increasing the yield for lignocellulosic biomass fermentations by possibly controlling the growth of C. acetobutylicum ATCC 824 at different mixtures of glucose and xylose based on the gained insight. Successful utilization of sugars suggests that lignocellulosic feedstocks can be a promising option for high yield fermentation.
Keywords:
biofuel, fermentation, sugar, yield, lignocellulosic sources
Topic:
Biomass Conversion Technologies for Liquid and Gaseous Fuels, Chemicals and Materials
Subtopic:
Bioethanol and sugars from lignocellulosic biomass
Event:
25th European Biomass Conference and Exhibition
Session:
3CO.15.5
Pages:
1042 - 1046
ISBN:
978-88-89407-17-2
Paper DOI:
10.5071/25thEUBCE2017-3CO.15.5
Price:
FREE
