acetobutylicum TSH1 increased to 99.85 % of the whole
population. The high ratio of Clostridium and low ratio of
Bacillus composition in the symbiotic system was beneficial
for butanol production.
When C/B ratio was changed from 10:1 to 1:1 and
1:10, the abundance of B. cereus TSH2 increased and
abundance of C. acetobutylicum TSH1 decreased correspondingly,
especially in the initial 4 h after inoculation.
The highest proportion of B. cereus TSH2 was
96.5 % when the C/B ratio was 1:10. However, the abundance
of B. cereus TSH2 sharply decreased to 0.92 % in
the later phase of fermentation which was similar to the
case of C/B ratio at 10:1, and C. acetobutylicum TSH1
finally became dominant species in the symbiotic system.
The difference between these two conditions was
that the abundance decline rate of B. cereus TSH2 at
C/B ratio 10:1 was lower than that of C/B ratio at 1:10.
Higher proportion and longer declining period indicated
that more nutrients were consumed by B. cereus TSH2.
The results explained why excessive of B. cereus TSH2
in the symbiotic system had a negative effect on butanol
production.