Spoilage date palm (Phoenix dactylifera L.) fruits were used as substrate for acetone, butanol
and ethanol (ABE) production by mixed culture of Clostridium acetobutylicum ATCC 824 and
Bacillus subtilis DSM 4451. B. subitlis was used to consume O2 and maintain strict anaerobic
conditions for ABE production by the strictly anaerobic C. acetobutylicum ATCC 824. The
total ABE production of 21.56 g L
1 was achieved at 75 g L
1 spoilage date fruits homogenate.
The maximum ABE productivity of 0.30 g L
1 h
1 and ABE yield of 0.42 were obtained
at 75 g L
1 spoilage date fruits homogenate by mixed culture without addition of a reducing
agent and N2 flushing. Addition of yeast extract (5 g L
1) or ammonium nitrate (1.6 g L
1) to
spoilage date fruits homogenate significantly enhanced ABE production. The combination
of yeast extract and ammonium nitrate markedly increased ABE production. These results
suggest that spoilage date fruits can be efficiently used for commercial ABE production.
The described protocol did not require addition of any costly reducing agent to medium or
flushing with N2 to ensure anaerobic conditions. This will makes the anaerobic fermentation
of date fruits homogenate more economical and reduces the cost of ABE production.