Journal
BIORESOURCE TECHNOLOGY
Volume 304, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.biortech.2020.122977
Keywords
Clostridium tyrobutyricum; Metabolic engineering; Butyric acid; Galactose catabolism; Spent coffee grounds
Funding
- Major Science and Technology Projects of Yunnan Province [2018ZG016]
- Scientific Research Funds of Yunnan Provincial Department of Education [2019J0685]
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Clostridium tyrobutyricum cannot utilize galactose, which is abundant in lignocellulose and red algae, as a carbon source for butyric acid production. Hence, when using galactose-rich coffee ground hydrolysate as the substrate, the fermentation performance of C. tyrobutyricum is poor. In this work, a recombinant strain, C. tyrobutyricum ATCC 25755/ketp, overexpressing galactose catabolism genes (galK, galE, gaff, and galP) from Clostridium acetobutylicum ATCC 824 was constructed for the co-utilization of glucose and galactose. Batch fermentation in the bioreactor showed that ATCC 25755/ketp could efficiently utilize galactose without glucose-induced carbon catabolite repression and consume nearly 100% of the galactose present in the spent coffee ground hydrolysate. Correspondingly, the butyric acid concentration and productivity of ATCC 25755/ketp reached 34.3 g/L and 0.36 g/L.h, respectively, an increase of 78.6% and 56.5% compared with the wild-type strain, indicating its potential for butyric acid production from hydrolysates of inexpensive and galactose-rich biomass.
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