Declining carbohydrate solubilization with increasing solids loading during fermentation of cellulosic feedstocks by Clostridium thermocellum: documentation and diagnostic tests

Table 1 Comparison of carbohydrate solubilization and utilization for mono- and cocultures

	Solid loading	Fractional carbohydrate solubilization	Fractional utilization of solubilized glucose	Fractional utilization of solubilized xylose
Corn stover
Monoculture	20 g/L	0.656 ± 0.017	0.938 ± 0.002	–
Monoculture	80 g/L	0.557 ± 0.010	0.946 ± 0.001	–
Coculture	20 g/L	0.749 ± 0.014	0.957 ± 0.001	0.779 ± 0.027
Coculture	80 g/L	0.632 ± 0.002	0.958 ± 0.001	0.798 ± 0.002
Switchgrass
Monoculture	20 g/L	0.406 ± 0.028	0.904 ± 0.015	–
Monoculture	80 g/L	0.259 ± 0.026	0.910 ± 0.003	–
Coculture	20 g/L	0.457 ± 0.042	0.952 ± 0.002	0.817 ± 0.002
Coculture	80 g/L	0.308 ± 0.021	0.954 ± 0.000	0.821 ± 0.002

Fractional sugar utilization calculated as one minus the mass of sugars found in the fermentation broth over the theoretical mass of sugars that have been solubilized based on fermented and unfermented solids. Sugar concentrations in the fermentation broth quantified in monomeric form via mild acid hydrolysis of the supernatant. No fractional utilization of xylose was detected in the monocultures

ISSN: 2731-3654