초록
<P><B>Abstract</B></P> <P>Bioconversion of C1 gases to produce chemicals has good application prospects. Here, the combination of trace metals optimization using a statistical method with variable-temperature cultivation was used to enhance alcohol synthesis during CO-rich off-gas fermentation by <I>Clostridium carboxidivorans</I> P7. Based on ATCC medium 1754, the optimum concentration of the trace metals was found to be 5-fold Ni<SUP>2+</SUP>, Co<SUP>2+</SUP>, SeO<SUB>4</SUB> <SUP>2+</SUP>, and WO<SUB>4</SUB> <SUP>2+</SUP>; 3.48-fold Cu<SUP>2+</SUP>; 0.55-fold MoO<SUB>4</SUB> <SUP>2+</SUP>; 0.5-fold Zn<SUP>2+</SUP> and (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB>·FeSO<SUB>4</SUB>·6H<SUB>2</SUB>O; and additional 44.32μM FeCl<SUB>3</SUB>·6H<SUB>2</SUB>O. The production of alcohol and organic acid changed to 4.40g/L and 0.50g/L from 2.16g/L and 2.37g/L, respectively, yielding an increase of alcohol-to-product ratio from 47.7% to 89.8%. By fermenting with the optimized medium and timed control of the incubation temperature (37°C [0–24h]–25°C [24–144h]), the alcohol titre further increased to 6.97g/L with 1.67g/L butanol and 1.33g/L hexanol, exceeding those previously reported for strain P7.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Trace metal composition was statistically optimized aiming at maximal alcohol titre. </LI> <LI> Fermentation at 25°C overrode bacterial flocculation and enhanced alcohol titre. </LI> <LI> Alcohol titre 6.97g/L exceeded the best reported for P7 in bottle fermentation. </LI> </UL> </P>