Fermentation of residual glycerol by Clostridium acetobutylicum ATCC 824 in pure and mixed cultures

ABSTRACT

The aim of this research was to estimate the production of hydrogen, organic acids and alcohols by the strain of Clostridium acetobutylicum ATCC 824 using residual glycerol as a carbon source. The experiments were carried out in pure and mixed cultures in batch experiments. Three different sources of inocula for mixed culture were used. Ruminal liquid from goats and sludge collected from two upflow anaerobic sludge blanket reactors treating municipal wastewater and brewery effluent were tested for hydrogen, organic acids and alcohols production with or without C. acetobutylicum ATCC 824. The main detected end-products from the glycerol fermentation were hydrogen, organic acids (acetic, propionic, butyric and caproic) and alcohol (ethanol and 1,3-propanediol – 1,3PD). High hydrogen (0.44 mol H₂/mol glycerol consumed) and 1,3PD (0.32 mol 1,3PD/mol glycerol consumed) yields were obtained when the strain C. acetobutylicum ATCC 824 was bioaugmented into the sludge from municipal wastewater using 5 g/L of glycerol. Significant concentrations of n-caproic acid were detected in the ruminal liquid when amended with C. acetobutylicum ATCC 824. The results suggest that glycerol can be used for the generation of H₂, 1,3PD and n-caproic acid using C. acetobutylicum ATCC 824 as agent in pure or mixed cultures.

KEYWORDS:

• Clostridium acetobutylicum
• bioaugmentation
• glycerol
• hydrogen
• 1
• 3-propanediol

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Brazilian Agricultural Research Corporation (Embrapa) [grant number 11/2012-Macroprograma 3]; the Brazilian National Council for Research and Technology (CNPq) [grant number 14/2013]; The Ceará State Foundation for the Support of Scientific and Technological Development (FUNCAP) [grant number 350365/2013-0/DCR 002400477.02.00/12].